Phosphorus Binders – Tanya's Comprehensive Guide to Feline Chronic Kidney Disease

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Overview

If your cat’s phosphorus level (in blood tests) is over 6 mg/dl (USA) or over 1.9 mmol/L (international), it is too high and you need to get it under control. In some cases you should take action sooner (see The Importance of Phosphorus Control).
Keeping phosphorus levels under control can help slow the progression of the CKD, reduce the risk of serious problems and make your cat feel better.
Feeding a food low in phosphorus is the first and best step. Ideally you want a food with a level below 0.5% phosphorus on a dry matter analysis (DMA) basis. Therapeutic kidney diet foods are the only complete foods which meet this criterion.
If your cat will not eat a therapeutic kidney diet, feeding a food as low in phosphorus as possible and adding a phosphorus binder to the food when appropriate can help control your cat’s phosphorus levels.
This page explains all you need to know about phosphorus binders.

Table of Contents

Why High Phosphorus Levels Matter

Phosphorus is a mineral essential for good health which is contained in many foods. The body is very good at regulating its phosphorus levels by removing excess phosphorus via the kidneys. However, the kidneys of a cat with CKD can no longer do this efficiently, so the vast majority of CKD cats will develop levels of phosphorus in their blood which are too high: this is known as hyperphosphataemia.

In contrast to the protein debate, there is no dispute about the importance of treating hyperphosphataemia because of the problems it causes. Indeed, an update on the Western Veterinary Conference 2017 reports on a presentation to the conference by Dr D Chew and states that “phosphorus restriction may be the “single most powerful treatment,” according to Dr. Chew.”

High phosphorus levels may:

make the cat feel unwell
cause CKD progression
cause an unpleasant complication of CKD called secondary hyperparathyroidism
may reduce a cat’s response to anaemia treatment

See The Importance of Phosphorus Control for more information on these issues.

Ways of Controlling Phosphorus Levels

Controlling Phosphorus Levels with Diet

The first step is to feed foods low in phosphorus, ideally a therapeutic kidney diet. Survival of cats with naturally occurring chronic renal failure: effect of dietary management (2000) Elliott J, Rawlings JM, Markwell PJ, Barber PJ Journal of Small Animal Practice 41(6) pp235-242 found that feeding a reduced phosphorus therapeutic kidney diet provided effective phosphorus control in two thirds of the cats in Stage 2 and 3 CKD. In addition, the cats eating the therapeutic kidney diet lived more than twice as long as the cats in the study who ate normal food with no phosphorus binder.

You can read more about how to control phosphorus levels using diet on The Importance of Phosphorus Control page, and why therapeutic kidney diets are the best choice on the Which Foods to Feed page..

Controlling Phosphorus Levels with Phosphorus Binders

If your cat will not eat a therapeutic kidney diet, or if his/her phosphorus levels are still too high (see The Importance of Phosphorus Control) despite feeding such a diet for a month, products called phosphorus binders are used.

Even if your cat is eating a low phosphorus diet, at some point it is quite possible that this will become insufficient to control your cat’s phosphorus levels. The role of phosphorus in feline chronic renal disease (2010) Chew D & Kidder A CVC in San Diego Proceedings states “Diet alone is not successful in adequate phosphorus control as chronic renal disease becomes more advanced. In these instances serum phosphorus concentration increases above the normal range or stays in the upper half of the normal range.”

Phosphorus binders work by binding with some of the phosphorus in the cat’s food in the intestine, which is then passed out in the stool. This prevents the phosphorus in the food from being absorbed into the bloodstream, and therefore over time this reduces the levels of phosphorus in the cat’s body.

To be effective, phosphorus binders must be given shortly before or, preferably, with food. You should start to see a difference in your cat’s blood phosphorus levels around 7-10 days after starting binders. There are instructions on how to give binders below.

Using binders is not as effective as feeding a therapeutic kidney diet, because binders cannot bind all the phosphorus contained in the food, so your cat will still be absorbing some of it. Therefore, if you do have to feed a non-therapeutic kidney food with a higher phosphorus content than is ideal (because the most important thing is that your cat eats), you should still aim to feed the lowest phosphorus food that your cat will eat. The Cat Food Data chapter has links to food data tables for you to check out the phosphorus levels of over 1500 cat foods in the USA. I am not recommending any of these foods, this is simply a list in order of phosphorus content.

Survey of dietary and medication practices of owners of cats with chronic kidney disease (2014) Markovich JE, Freeman LM, Labato MA and Heize CR Journal of Feline Medicine and Surgery 22 found that only 22% of the 1080 cats in the survey were receiving phosphorus binders. Not all of the cats may have required binders at the time of the survey but this is still a very low percentage considering the consequences of not controlling phosphorus levels in CKD. So if your vet does not offer you phosphorus binders, do not assume you do not need them, ask for your cat’s phosphorus levels and take action if your cat’s levels are too high.

When to Start Phosphorus Binders

You should not normally need to use binders if your cat is eating a therapeutic kidney diet, at least in the early stages of CKD, because the therapeutic diet should be sufficient to control your cat’s phosphorus levels. However, this is not always the case, particularly as the CKD worsens. The role of phosphorus in feline chronic renal disease (2010) Chew D & Kidder AC CVC in San Diego Proceedings says “Intestinal phosphate binders should be added if serum phosphate remains increased after one month of consuming the renal diet or if the switch to the renal diet is not accepted by the animal.”

Please see The Importance of Phosphorus Control: to learn when you may need to start using binders and discuss this with your vet. Remember, a phosphorus level within normal range is not sufficient for a CKD cat.

If your cat isn’t eating at all, there is little point giving phosphorus binders because your cat isn’t ingesting any phosphorus in food that needs binding. However, if you assist feed (as you should if your cat is not eating), you can add binders to the food you are feeding (although this may not be necessary if you are assist feeding a therapeutic kidney diet).

Types of Phosphorus Binder

There are a large number of phosphorus binders available, which I have divided into the following categories based upon the primary binding ingredient.

Only three types are commonly used in cats: aluminium hydroxide, calcium carbonate and lanthanum carbonate, though there is growing interest in the use of niacinamide. Most people on Tanya’s CKD Support Group use aluminium-based products.

Many of these products are available as simple over the counter antacids, but branded products are also available. All types have pros and cons.

Aluminium-Based Binders

There are three main types of aluminium-based binders, but aluminium hydroxide is the best choice within this family of medications.

Aluminium Magnesium Hydroxide

This type of binder, as the name suggests, also contains magnesium. These products are commonly sold as antacids (but are not the best choice for that purpose for CKD cats). Brand names include Maalox, Mylanta, Milk of Magnesia or Aludrox.

Binders containing magnesium are not suitable for CKD cats because they can cause high magnesium levels in the blood, which in turn may cause urinary tract problems such as stones in some cats.

PetCoach states “Do not use magnesium containing products in animals with kidney failure.”

Sucrose Aluminium Hydroxide

Sucrose aluminium hydroxide is also known as sucralfate or Carafate. It coats the digestive tract, so is sometimes used to help CKD cats with mouth ulcers or gastrointestinal bleeding.

One old study, Changes in serum phosphorus, calcium and alkaline phosphatase due to sucralfate (1986) Vucelić B, Hadzić N, Gragas J, Puretić Z International Journal of Clinical Pharmacology, Therapy and Toxicology 24(2) pp93-6, did find sucralfate was effective as a binder in humans.

Therefore a vet may occasionally also recommend sucralfate as a phosphorus binder, but it is not a good choice for cats. Evaluating sucralfate as a phosphate binder in normal cats and cats with chronic kidney disease (2016) Quimby JM & Lappin M Journal of the American Animal Hospital Association 52(1) pp8-12 evaluated sucralfate’s efficacy as a phosphorus binder in healthy cats and in CKD cats with phosphorus in the normal range. There was no change in phosphorus levels in the healthy cats, but 14.7% of them vomited after being given it. The CKD cats given sucralfate did not show reduced phosphorus levels but sixty percent (three cats out of five) exhibited vomiting, anorexia and elevated BUN and creatinine levels, to such a degree that the study was discontinued. If your vet prescribes sucralfate, I would show them this study.

If you are using sucralfate for mouth ulcers or gastrointestinal bleeding at the same time as using aluminium hydroxide as a phosphorus binder, you might possibly be able to reduce your dosage of aluminium hydroxide, though this is not a given based on the results of the above study.

Aluminium Hydroxide

Aluminium hydroxide, Al(OH)_3,is the best choice of the aluminium-based binders. Its advantages are that it is effective, odourless and tasteless (if you buy the correct type), available over the counter in some countries (though you will have to use a local compounding pharmacy or mail order in the USA if you want the odourless and tasteless type) and relatively cheap.

See below for stockists.

Aluminium Hydroxide Formulations

Many vets are reluctant to prescribe aluminium-based binders because they think cats hate the taste. This may be because many vets seem only to be familiar with AlternaGel, a peppermint-flavoured aluminium hydroxide binder which most cats hate, so it then becomes a self-fulfilling prophecy. AlternaGel also contains potassium citrate, which is not a good idea because citrate can increase the absorption of aluminium within the body.

Odourless and Tasteless Powder

Fortunately, there are alternatives, including tasteless and odourless powder varieties which most cats do not seem to notice in their food.

Contrary to what some vets and pharmacists seem to believe, you do not need a prescription to buy these products.

I do not recommend buying from eBay etc because you need pharmaceutical grade aluminium hydroxide, and many products available on auction sites are not pure enough and not suitable for CKD cats.

Thriving Pets

Sells a popular loose powdered product. Their product is around 85% pure (no aluminium hydroxide product will be 100% pure because it is a natural mined product).

Phos-Bind

Is a brand of loose aluminium hydroxide binder made by Rx Vitamins. Phos-Bind is around 77% pure, so not as pure as the Thriving Pets product.

See below for information on where to buy these products, including links to mail order suppliers who can ship to the UK, USA, Canada and Australia. You may also be able to obtain powdered aluminium hydroxide from your local compounding pharmacy.

IrcVet

IrcVet is marketed as a nutritional supplement. Some sellers state that it contains 100mg of aluminium hydroxide but, according to the manufacturer, it contains 240mg of calcium acetate, along with quercetin, resveratrol, folic acid, vitamins B6 and B12 and dry artichoke extract,.

Aluminium Hydroxide Side Effects

Sometimes aluminium hydroxide-based binders may cause constipation, so watch for this when you first start them and be ready to start a suitable treatment if required.

Please see below for more information on aluminium toxicity.

Aluminium Hydroxide Interactions

Potassium Citrate

Prescribers’ Digital Reference mentions that products containing citrate may increase the absorption of aluminium, which could increase the risk of aluminium toxicity (though apparently these findings have not been replicated in cats).

Potassium citrate is given to some CKD cats by itself, either to treat low potassium levels or to treat metabolic acidosis). If you are using potassium citrate in this way, give it at least two hours apart from aluminium-based binders.

Potassium citrate is also found in many therapeutic kidney diets. This can be trickier to handle because aluminium hydroxide binders need to be given with food. You will probably not need to use phosphorus binders if you are using a therapeutic kidney diet, at least in early to mid stage CKD, but if you do have to use both, check the therapeutic kidney food you are feeding to see if it contains potassium citrate (other forms of potassium are not a problem) and consider switching to another therapeutic kidney food which does not contain potassium citrate. It might also be worth switching to another type of phosphorus binder, either completely or by mixing aluminium hydroxide with foods not containing potassium citrate and adding another binder to foods which do contain potassium citrate. Speak to your vet about the best way forward.

Other Interactions

Chronic kidney disease (CKD) in dogs and cats — staging and management strategies (2015) Chew D A Presentation to the Virginia Veterinary Medical Association 2015 Virginia Veterinary Conference says “Due to varying effects of intestinal phosphate binders to limit absorption of drugs, it is advisable to give other drugs 1 hour before or 3 hours after any intestinal phosphate binder is given.”

The following specific interactions are noted:

According to Plumb’s Veterinary Drug Handbook, aluminium hydroxide should be given two hours apart from enrofloxacin (Baytril), an antibiotic. It is probably wise to keep aluminium hydroxide away from antibiotics generally, particularly those in the same family as Baytril (this includes marbofloxacin (Zeniquin).
Plumb’s also recommends separating aluminium hydroxide from corticosteroids.
Aluminium hydroxide should ideally be given separately from oral iron supplements because the aluminium hydroxide may reduce the absorption of the iron.
Plumb’s Veterinary Drug Handbook also advises giving aluminium hydroxide two hours apart from famotidine (Pepcid AC) because it may interfere with the absorption of the treatment, which would make it less effective. However, RX Med states that “concomitant use of aluminum hydroxide/magnesium hydroxide at commonly used doses, does not influence the pharmacodynamics or bioavailability of Pepcid AC.” I would try to err on the side of caution and still separate famotidine from phosphorus binders and ACE inhibitors if you can, but if this is difficult for you, e.g. because of work commitments, just do the best you can.
Aluminium hydroxide binders should be given two hours apart from ACE inhibitors, because the binder may reduce the bioavailability of the ACE inhibitors. Drugs has more information about this.
PennState Hershey mentions that vitamin C may interact adversely with products containing aluminium, such as phosphorus binders. Cats do not need vitamin C supplements anyway, because their bodies can manufacture all the Vitamin C they need.
I don’t know if slippery elm bark would interfere with aluminium hydroxide, as far as I know this has never been studied, but it might be possible in theory. However, if you are adding slippery elm bark to food once or twice a day, I would still mix binders in with that food in the hope that at least some of the phosphorus would be bound.

Aluminium Toxicity

You may have read that there is a risk of aluminium toxicity from the aluminium in aluminium hydroxide medications. This applies in particular to human patients on dialysis, because aluminium is used in the dialysis process. Do aluminium hydroxide binders continue to have a role in contemporary nephrology practice? (2011) Mudge DW, Johnson DW, Hawlet CM, Campbell SB, Isbel NM, van Eps CL & Petrie JJB Nephrology 12 states “Available historical evidence however, suggests that neurological toxicity may have primarily been caused by excessive exposure to aluminium in dialysis fluid, rather than aluminium-containing oral phosphate binders. Limited evidence suggests that aluminium bone disease may also be on the decline in the era of aluminium removal from dialysis fluid, even with continued use of aluminium binders…The relative contribution of aluminium binders to aluminium toxicity would appear to be minor based on the available evidence.” Do oral aluminium phosphate binders cause accumulation of aluminium to toxic levels? (2011) Pepper R, Campbell N, Yaqoob MM, Roberts NB & Fan SLS BMC Nephrology 12 found that even patients on dialysis did not develop aluminium toxicity if changes were made to the dialysis process (during which patients may be exposed to dialysate water which is contaminated with aluminium), but the patients in this study were on relatively low doses of aluminium hydroxide.

Since cats are not normally on dialysis, aluminium toxicity was not thought to be a concern for cats (or dogs), especially since even in humans it takes years before it becomes a problem, and cats and dogs don’t live as long as humans. Recently, however, there has been increasing concern about the possible risk of aluminium toxicity in cats using aluminium hydroxide based binders. This is partly because of a study which reported on aluminium toxicity in two dogs on binders, Aluminum toxicity following administration of aluminum-based phosphate binders in 2 dogs with renal failure (2008) Segev G, Bandt C, Francey T & Cowgill LD Journal of Veterinary Internal Medicine 22(6) pp1432-5. There is no abstract available for this study, but Treatment options for hyperphosphataemia in feline CKD: what’s out there? (2009) Kidder AC & Chew D Journal of Feline Medicine & Surgery 11(11) pp813-24 reported that the two dogs in question developed “probable aluminum toxicity” after being on binders for only 62 and 65 days. The symptoms seen were “severe neuromuscular abnormalities.” The dogs were on dosages of 125mg/kg per day (or 56mg per lb body weight) and 200 mg/kg (or 91mg per lb bodyweight) per day, which are not particularly high doses. However, both these dogs had been on dialysis, though apparently the dialysate water was not contaminated with aluminium.

Partly because of this study, vets are becoming increasingly aware of the need for caution and awareness when using aluminium hydroxide binders in cats too, particularly when using large doses. Chronic kidney disease (CKD) in dogs and cats — staging and management strategies (2015) Chew D Presentation to the Virginia Veterinary Medical Association 2015 Virginia Veterinary Conference says “THERE IS NO KNOWN SAFE DOSE OF ALUMINUM SALTS FOR HUMANS WITH CKD. Detrimental effects of aluminum based phosphate binders as described in humans seen in humans have not been systematically evaluated in small animal patients and are rarely clinically appreciated. As cats with CKD can live for years on treatment, concerns for aluminum accumulation deserve more study as to long-term safety.”

Physical symptoms to watch for include muscle weakness or neurological problems, such as stumbling and an awkward gait (although, just to complicate matters, these can actually be signs of uncontrolled phosphorus levels too, see The Importance of Phosphorus Control). One possible early sign of aluminium toxicity is a change in MCV. This is a measure of red blood cell size. If your cat has a low MCV (known as microcytosis), this means the red blood cells are smaller than usual. Although this may simply indicate iron deficiency, it may also be a sign of aluminium toxicity. This sign normally appears before you see physical symptoms, so be sure to monitor your cat’s MCV levels.

If you are using potassium citrate (perhaps to treat metabolic acidosis), give this at least two hours apart from phosphorus binders. This is because, as Prescribers’ Digital Reference explains, products containing citrate can in theory increase the absorption of aluminium, which could increase the risk of aluminium toxicity. Many therapeutic kidney diets contain potassium citrate. See above for more information on aluminium hydroxide and potassium citrate.

Try not to worry too much. I am only aware of one case of aluminium hydroxide toxicity in cats to date (this cat was given massive doses of aluminium hydroxide, more than twice as much as she would normally be given based upon Dr Nagode’s protocol below), and most cases in dogs have occurred in dogs taking over 200 mg/kg. Updates in feline chronic kidney disease (2008) Langston CL states “Excessive absorption of aluminum can lead to toxicity, including anemia and neurologic symptoms, but this seems uncommon in veterinary practice.” In contrast, the dangers of elevated phosphorus control are very real, and very common, and controlling phosphorus is essential for your cat’s wellbeing.

If your cat has phosphorus levels that require large amounts of aluminium hydroxide, or if you cannot control your cat’s phosphorus levels with aluminium hydroxide only, consider adding another phosphorus binder. Most people in this situation use lanthanum carbonate (Renalzin or Fosrenol). See below for suggestions on dosage.

If you think your cat may have aluminium toxicity, I would ask for a referral to a vet school or a neurologist if possible. Chelation therapy plus dialysis helped to remove the aluminium from dogs with aluminium toxicity, and indeed following treatment the neurological problems experienced by the dogs in the above study were successfully reversed.

Aluminium Hydroxide: Other Concerns

If you buy aluminium hydroxide gel or powder in the USA, you may see a warning about arsenic which bizarrely supposedly only applies to people living in California. This is to comply with that state’s legal requirements. The fact is that aluminium hydroxide is a naturally occurring product which is mined, and therefore it contains a naturally occurring tiny amount of arsenic of no more than 8 parts per million. This is no more than you might find in soil or in vegetables grown in soil. However, if you want to be on the safe side, you might wish to avoid inhaling the powder.

In some cases when buying aluminium hydroxide, you may see an expiration date on it. This is usually to comply with pharmacy laws, but in practice, since aluminium hydroxide is a mineral that is mined from the earth, it cannot really expire, so if you are using a gel or powder form of aluminium hydroxide, I would not worry too much about expiry dates. However, if you are using a suspension of some kind, it may expire because of other ingredients in the mix.

Lanthanum Carbonate

Lanthanum carbonate is a newer type of phosphorus binder. Like aluminium hydroxide, it appears to be tasteless and Pharmacology of the phosphate binder, lanthanum carbonate (2011) Damment SJP Renal Failure 33(2) pp217–224 found that lanthanum carbonate-based binders appear to be as effective as aluminium hydroxide-based binders.

Multicenter prospective randomized, double-blind comparative study between lanthanum carbonate and calcium carbonate as phosphate binders in Japanese hemodialysis patients with hyperphosphatemia (2008) Shigematsu T Clinical Nephrology 70(5) pp404-10 found lanthanum carbonate and calcium carbonate had similar levels of efficacy in lowering phosphorus levels, but lanthanum carbonate was better at lowering the incidence of elevated calcium levels.

However, Effects of nicotinamide and lathanum carbonate on serum phosphate and fibroblast growpth factor-23 in CKD: the COMBINE trial (2019) Ix JH, Isakova T, Larive B, Raphael KL, Raj DS, Cheung AK, Sprague SM, Fried LM, Gassman JJ, Middleton JP, Flessner MF, Block GA & Wolf M Journal of the American Society of Nephrology 30(6) pp1096-1108 looked at the effects of lanthanum carbonate and/or niacinamide as a phosphorus binder in human patients and found “LC and/or NAM treatment did not significantly lower serum phosphate or fibroblast growth factor 23 (FGF-23) in stage 3b/4 CKD over 12 months. Although these agents appeared safe, intestinal symptoms limited adherence.”

Lanthanum Carbonate-based Formulations

Fosrenol is a human medication.

CatneyOne is a version of lanthanum carbonate from Dechra for cats.

Nefrokrill is an Italian product for cats that may become more widely available.

Fosrenol

Fosrenol is the human version of lanthanum carbonate that has been available in the USA since 2005 and is gradually being used in cats. A prescription is required.

Fosrenol comes in the form of extremely expensive tablets which are supposed to be chewed, but in order to use them for cats, most people crush the tablets. In 2015 a powder form was released. In humans this is supposed to be mixed with apple sauce or similar but I imagine you could simply add it to your cat’s food.

See below for stockists.

Eurek Alert has a press release regarding the approval process for Fosrenol in the USA.

Catney One

Porus One is an oral adsorbent, which is intended to help reduce uraemic toxins. Its manufacturer has now introduced a lanthanum carbonate based phosphorus binder called Catney One. It has been available in Europe for some time and will be launched in the USA in June 2025.

The recommended dosage of Catney One is 1 sachet (520 mg) daily per cat. It can be mixed with food. Catney One should be given three hours before or one hour after oral medications.

NefroActiv

NefroActiv is a newer binder in the UK that contains:

lanthanum carbonate
lespedeza capitata extract (which is thought to reduce BUN, but which may also have diuretic effects; and
chitosan (chitosan is commonly used as an oral adsorbent, and is intended to help reduce uraemic toxins).

Personally I would prefer a binder that simply contains lanthanum.

Nefrokrill

Nefrokrill is a product from Italy that may also be available in other parts of Europe. It comes in small capsules (which they call pearls), and each contains a combination of:

lanthanum carbonate (280mg)
essential fatty acids (EPA 245 mg, DHA105 mg and vitamin E 20mg, with additional krill oil of 80mg)
potassium citrate (22mg)
L-arginine (15mg)

The usual dosage is one pearl per day.

Nefrokrill would not be suitable if your cat has high potassium levels. Please also read up on krill oil.

Lanthanum Carbonate-based Binders Side Effects

The most common side effects for humans taking lanthanum carbonate are nausea, vomiting and diarrhoea, and I have also heard of CKD cats who developed nausea and vomiting whilst taking Renalzin, a discontinued lanthanum-based binder for cats. The manufacturer of Renalzin confirmed to one person’s vet that these were possible side effects.

In 2011 the US Food and Drug Administration issued a Safety Labeling Change which states “There have been reports of serious cases of gastrointestinal obstruction, ileus, and fecal impaction reported in association with lanthanum, some requiring surgery or hospitalization. Risk factors for gastrointestinal obstruction identified from post-marketing reports include alteration in gastrointestinal anatomy (e.g., history of gastrointestinal surgery, colon cancer) hypomotility disorders (e.g., constipation, ileus, diabetes) and concomitant medications (e.g., calcium channel blockers). Some cases were reported in patients with no history of gastrointestinal disease.” Amlodipine, used to treat high blood pressure in CKD cats, is a calcium channel blocker, so check with your vet before using both.

Effects of phosphorus binders in moderate CKD (2012) Block GA, Wheeler DC, Persky MS, Kestenbaum B, Ketteler M, Spiegel DM, Allison MA, Asplin J, Smits G, Hoofnagle AN, Kooienga L, Thadhani R, Mannstadt M, Wolf M & Chertow GM Journal of the American Society of Nephrology 23(8) pp1407-15 found that binders containing lanthanum carbonate did reduce phosphorus levels but also caused calcium build up in blood vessels, which can lead to heart problems.

Lanthanum Carbonate-based Binders Interactions

Chronic kidney disease (CKD) in dogs and cats — staging and management strategies (2015) Chew D A Presentation to the Virginia Veterinary Medical Association 2015 Virginia Veterinary Conference says “Due to varying effects of intestinal phosphate binders to limit absorption of drugs, it is advisable to give other drugs 1 hour before or 3 hours after any intestinal phosphate binder is given.”

Plumbs Veterinary Drugs Handbook says “Drug interactions with lanthanum carbonate have not been reported, but as it is a binding agent similar to aluminum, it seems prudent to separate by two hours dosing lanthanum and the following:”

Baytril, an antibiotic, and other antibiotics in the quinolone family. Fosrenol insert leaflet says “Oral quinolone antibiotics must be taken at least 1 hour before or 4 hours after Fosrenol.” It is probably wise to keep lanthanum carbonate away from antibiotics generally.
ace inhibitors
famotidine (Pepcid AC) or ranitidine (Zantac 75), which are sometimes used to treat gastric hyperacidity, because lanthanum carbonate may interfere with the absorption of the treatment, which would make it less effective.
iron, because lanthanum carbonate may reduce absorption of iron.
corticosteroids
Fosrenol insert leaflet says “There is a potential for FOSRENOL to interact with compounds that bind to cationic antacids (i.e., aluminum-, magnesium-, or calcium-based);therefore, do not take such compounds within 2hours of dosing with Fosrenol.”

I don’t know if slippery elm bark would interfere with lanthanum carbonate, as far as I know this has never been studied, but it might be possible in theory. However, if you are adding slippery elm bark to food once or twice a day, I would still mix binders in with that food in the hope that at least some of the phosphorus would be bound.

Calcium-Based Binders

Sometimes your vet will recommend using a calcium-based antacid as a phosphorus binder.

Over the counter products, such as Tums or PhosLo, are widely available and cheap but many vets also sell commercial products made for cats. More of these products appear every year (I really should create my own, I’ve just got to find my USP. Maybe a picture of Tanya on the container?), but common factors are that they all have additional ingredients and cost a lot more than OTC products. See below for stockists, though personally I would not use any of them; I would rather use aluminium hydroxide.

Calcium Acetate

Calcium acetate-based binders bind 2-3 times as much phosphorus as calcium carbonate-based binders. On the other hand, they are more likely to cause elevated calcium levels in the blood (hypercalcaemia). They also do not bind as much phosphorus as aluminium hydroxide or lanthanum carbonate.

One over the counter brand is PhosLo. Newer products marketed for cats include Naraquin and IrcVet.

Naraquin

Naraquin is a newish binder (released 2022) from the manufacturer of Cosequin (an arthritis treatment) that is sold through vets. It contains a “proprietary blend” of the following:

ferric citrate 150mg
calcium acetate 40mg (see above)
chitosan 40mg (commonly used as an oral adsorbent, which is intended to help reduce uraemic toxins)
omega 3 fatty acids (essential fatty acids) 25mg
Yeast Extract and Marine Lipids 140mg

The dosage is one capsule for each meal.

Ferric citrate for the treatment of hyperphosphatemia and iron deficiency anaemia in patients with NDD-CKD: a systematic review and meta-analysis (2024) Ding X, Sun S, Zhang J, Zhao H, Lun F, Liu X, Zhen Y, Dong J & Wu J Frontiers in Pharmacology 15 reviewed a number of studies into the use of ferric citrate as a phosphorus binder in human NDD (not dialysis dependent) patients. It concludes that ferric citrate can be helpful as both a phosphorus binder and to help with iron deficiency anaemia, but that it could cause digestive side effects such as constipation (which is common with iron supplements), diarrhoea and vomiting in some patients.

Since Naraquin contains iron, I would advise not using it at the same time as aluminium hydroxide (see aluminium hydroxide interactions).

I have not heard from anyone who has used Naraquin as yet.

IrcVet

IrcVet is marketed as a nutritional supplement. Some sellers state that it contains 100mg of aluminium hydroxide but, according to the manufacturer’s website, it contains 240mg of calcium acetate, along with quercetin, transresveratrol, folic acid, vitamins B6 and B12 and dry artichoke extract. It seems unnecessarily complicated to me.

Calcium Carbonate

You can buy calcium carbonate-based binders over the counter — Tums is a widely available product of this type. Dosage for OTC calcium carbonate is below.

The risk of hypercalcaemia is lower with calcium carbonate-based binders than with calcium acetate-based, though it still exists. Calcium carbonate-based products only bind a third to a half of the phosphorus that calcium acetate-based binders bind, and a lot less than aluminium hydroxide or lanthanum carbonate.

A number of manufacturers make calcium carbonate-based products for cats with additional ingredients and their own particular dosing schedules.

Ipakitine/Epakitin (with chitosan)
Renakitin (with chitosan)
Renal P (with chitosan)
Aventi Kidney Complete or RenalPro (with chitosan)
Renaltan (with chitosan and other ingredients)
RenalVet (with chitosan and vitamin D)
Nutraren (with chitosan and essential fatty acids)
Easypill Rena’Expert (with yucca and essential fatty acids)
Pronefra (with magnesium carbonate, chitosan and other ingredients)
Renate (with magnesium carbonate and other ingredients)

Ipakitine/Epakitin

Contains calcium carbonate and chitosan

I pakitine has been available in the UK since December 2002 and in the rest of Europe for even longer. Ipakitine was introduced into the USA in 2005, under the slightly different name of Epakitin.

Ipakitine/Epakitin: What is It?

Ipakitine is a combination of:

calcium carbonate
chitosan, commonly used as an oral adsorbent, which is intended to help reduce uraemic toxins.

Renal P, Pronefra, Renakitin, R enalVet and Nutraren also contain these ingredients.

The manufacturers’ websites do not state exactly how much calcium carbonate is in Ipakitine/Epakitin, however:

Drugs states that 1g of the Canadian version of Epakitin contains 100mg of calcium carbonate and 80mg of chitosan. Chronic kidney disease (CKD) in dogs and cats – staging and management strategies (2015) Chew D A Presentation to the Virginia Veterinary Medical Association 2015 Virginia Veterinary Conference states that it contains 8% chitosan and 10% calcium carbonate, which would tie in with this.
The Material Data Safety Sheet states that Ipakitine contains 5-20% calcium carbonate, which seems to be a wide range.
I presume all the versions are the same.

Ipakitine Dosage

The recommended dose is 1g of Epakitin per 5kg (11 lb) of cat given twice a day with meals. This equates to 200mg of calcium carbonate per day for an 11 lb (5kg) cat, which is is within typical veterinary guidelines for calcium carbonate dosages, see below.

See below for stockists.

Ipakitine Research

Effects of an intestinal phosphorus binder on serum phosphorus and parathyroid hormone concentration in cats with reduced renal function (2008) Brown SA, Rickertson M & Sheldon S International Journal of Applied Research in Veterinary Medicine 6(3) pp155-160 reports on a small randomised placebo-controlled study of twelve cats at the University of Georgia College of Veterinary Medicine (partly funded by the manufacturers) which indicated that Epakitin reduced phosphorus levels in the cats, who were fed a commercial non-therapeutic diet and who were in IRIS Stages 1 and 2. The study did not find that Ipakitine reduced BUN or creatinine levels, however the cats in this study did not have naturally occurring kidney disease, which the cats in the 2004 study below did.

Effects of a dietary chitosan and calcium supplement on calcium and phosphorus metabolism in cats (2004) Wagner E, Schwendenwein I, Zentek J Berliner und Münchener tierärztliche Wochenschrift 117 pp310-315 found that Ipakitine reduced phosphorus and BUN (urea) levels in the CKD cats in the trial.

Ipakitine Usage

In the USA, Epakitin is marketed as a “chitosan-based phosphorus binder” which is odd because chitosan is not a phosphorus binder. Certainly some vets seem to sell it to clients whose cats do not have elevated phosphorus levels, so they are presumably advocating it for its chitosan-related effects.

Perhaps because it is not considered to be purely a phosphorus binder, the recommendation is to give it twice a day rather than divided between all meals. Although ideally you should divide the total daily dose between all meals, it does seem to work to a degree when given twice a day. My own vet in the UK has seen falls in creatinine and urea in some cats when using Ipakitine and no other treatments. I used it myself for Ollie who did not have very high phosphorus levels, and to whom none of the cautions below applied. It did appear to reduce his phosphorus levels.

Ipakitine was originally only supposed to be given for six months, but I have heard of cats who have been on it for longer with no obvious problems. The manufacturer has previously stated it should be OK to give it for longer for six months under veterinary supervision, and the manufacturers’ websites no longer seem to mention a six month period.

Ipakitine How To Give

Ipakitine comes in powder form, and is apparently tasteless. It is sprinkled on the cat’s food for a period of up to six months, although it may be used for longer if your vet agrees.

Dosage is weight-related, and phosphorus levels do not appear to be taken into account when determining how much to give.

Ipakitine Side Effects and Interactions

The Material Data Safety Sheet states that Ipakitine contains a high (70-90) percentage of lactose, so I would not use it if your cat is lactose intolerant.

Calcium-containing products such as Ipakitine may cause increased calcium levels (hypercalcaemia). The risk is lower with calcium carbonate-based binders than with other calcium-based binders, and the manufacturer claims it is less likely to happen with the form of calcium carbonate which they use, but if your cat is taking Ipakitine, it would probably be wise to monitor his/her calcium levels.

Ipakitine is not normally suitable for cats who already have high calcium levels. It also should not be used in cats taking calcitriol.

Renakitin

Contains calcium carbonate and chitosan

Renakitin is made by Pet Health Solutions and contains:

calcium carbonate
chitosan, commonly used as an oral adsorbent, which is intended to help reduce uraemic toxins.

Drugs has some information about it.

Easypill Rena’Expert

Contains calcium carbonate and chitosan

EasyPill Rena’Expert is a calcium carbonate-based phosphorus binder made by Vetinnov in France and available in a number of European countries. As the name suggests, this product is intended to offer high palatability. It contains:

calcium carbonate
chitosan

but specifics are hard to come by.

The recommended dose is one 2mg pellet per day given just before food

Personally I wouldn’t use it, mainly because of the lack of information on its exact composition, but I also cannot forgive its infuriating name (what’s wrong with the letter L??).

Renal P by Candioli

Contains calcium carbonate, chitosan and bicarbonate of soda

Renal P is made by Candioli Pharma in Italy and is commonly offered to people in Italy, and occasionally to people in other parts of Europe.

This product contains:

calcium carbonate
chitosan
bicarbonate of soda, used to treat metabolic acidosis.

Since not every CKD cat needs treatment for metabolic acidosis, I would give Renal P a miss.

Aventi Kidney Complete or RenalPro

Contains calcium carbonate, chitosan, potassium citrate, bicarbonate of soda

Aventi Kidney Complete is commonly offered to people in Canada, where it is marketed by Aventix Animal Health. It contains the following ingredients:

calcium carbonate
chitosan, commonly used as an oral adsorbent, which is intended to help reduce uraemic toxins.
potassium citrate
fructooligosaccharides (FOS), presumably for their prebiotic properties, but not normally recommended for CKD cats
probiotics
some of the B vitamins
bicarbonate of soda, used to treat metabolic acidosis.

Drugs also has some information about it.

Since not every CKD cat needs treatment for metabolic acidosis, I would give Renal P a miss.

RenalPro is a similar product made by a Canadian company called ProConcepts Animal Health. It also contains calcium carbonate, chitosan and potassium citrate, but no bicarbonate of soda or FOS.

Personally, if my cat needed a potassium supplement, I would give it separately, and if my cat didn’t need a potassium supplement, why would I give a product containing potassium?

Renaltan

Contains calcium carbonate, chitosan, B vitamins, essential fatty acids and minerals

Renaltan is a liquid calcium carbonate-based phosphorus binder made by Recoactiv (RecoVet) in Germany. It also contains some B vitamins, essential fatty acids and minerals. 10ml contain 500mg of calcium carbonate but the manufacturer’s website does not specify the precise amounts of any of the other ingredients.

The manufacturer claims that this product stimulates the appetite and increases food intake, which I presume is because of the B vitamins. It also claims that by using this product, you can avoid using therapeutic kidney food in IRIS Stages 1 and 2 because you are controlling phosphorus levels but leaving protein levels untouched. Whilst it is true that it is not necessarily a good idea to reduce protein levels in IRIS Stages 1 and 2 (see Nutritional Requirements), therapeutic kidney diets do have other attributes. See Which Foods to Feed for information on when and why to use therapeutic kidney diets.

RenalVet

Contains calcium carbonate, chitosan and vitamin D

RenalVet is a product from VetExpert that appears to be commonly offered to people in Greece, Turkey and eastern Europe. It contains 200 mg calcium carbonate, 100 mg chitosan and 0,002mg of vitamin D. I have no idea why it contains vitamin D, which is not recommended for CKD cats, but I would not use this product for that reason.

RenalVet comes in capsules with a twist-off top and the recommended dose is 1 capsule a day for cats up to 10kg.

Nutraren

Contains calcium (lithothamnion calcareum), chitosan, essential fatty acids and vitamin E

Nutraren is a calcium-based binder. It contains lithothamnion calcareum, which is derived from marine algae, but which appears to be a form of calcium carbonate. It also contains chitosan, essential fatty acids and vitamin E. Each capsule contains:

96mg – EPA (eicosapentaenoic acid) – essential fatty acids
62mg – DHA (docosahexaenoic acid) – essential fatty acids
32mg – calcium (lithothamnion calcareum)
50mg – chitosan, commonly used as an oral adsorbent, which is intended to help reduce uraemic toxins.
10mg – vitamin E (d-alpha tocopherol)

The usual dose is one capsule per day for cats weighing up to 5kg, or two capsules a day up to 10kg.

Pronefra

Contains calcium carbonate, magnesium carbonate, chitosan, astralagus, fish protein hydrolysate

Pronefra, made by Virbac, was launched in 2014. It is marketed as a “supplementary food” and contains four main ingredients:

calcium carbonate (3.57%) and magnesium carbonate (0.95%) as phosphorus binders
chitosan (0.95%), commonly used as an oral adsorbent to bind with uraemic toxins
astragalus (9.5%) for renal fibrosis
fish protein hydrolysate (1.9%), which they claim helps with hypertension

Binders containing magnesium are not ideal for CKD cats because they can cause high magnesium levels in the blood, which in turn can sometimes cause urinary tract problems such as stones in some cats.

Astragalus is thought to be an antioxidant but Holisticat states that astragalus should only be used short term in cats, see Holistic Treatments.

Fish protein hydrolysate is also found in Astro’s Oil Renal Care Protein, though I am not sure whether Pronefra contains enough to make a difference, and I have no idea how exactly it is supposed to help with hypertension.

The recommended dose of Pronefra is 1 ml per 4 kg (9lbs) of cat twice a day, mixed with food or syringed directly into the cat’s mouth immediately before or after eating. I do not yet know how much calcium carbonate this would contain.

Effect of a product containing the dietary phosphate binders calcium and magnesium carbonate associated with other reno-protectant substances (Pronefra) on blood parameters and mineral balance in adult cats (2014) Bernachon N, Fournel S, Gatto H, Monginoux P & McGahie D International Journal of Applied Research in Veterinary Medicine 12(1) pp8017 found that giving Pronefra to ten healthy 2-5 year old cats for twelve weeks led to decreased creatinine and phosphorus levels. Calcium and magnesium levels remained within normal range.

Comparative palatability of five supplements designed for cats suffering from chronic renal disease (2014) Bernachon N, Fournel S, Gatto H, Monginoux P & McGahie D Irish Veterinary Journal 67(1) p10 compared the palatability of five products intended for CKD cats: Ipakitine, Azodyl, Renalzin, Rubenal and Pronefra. The study, undertaken by employees of Virbac, the manufacturer of Pronefra, found that Pronefra was the most palatable.

I haven’t heard from too many people who have used it as yet (May 2025, but one person said it made her cat vomit and a couple of people said their cats didn’t like the taste. Personally, I don’t think I would bother with Pronefra.

Renate

Contains calcium carbonate, magnesium carbonate, curcumin, cranberry, vitamins B and E

Renate is yet another calcium carbonate-based product (with lots of other ingredients to differentiate it from its competitors) which was launched in the UK in 2017. It is not to be confused with a product of the same name in the USA which is a multivitamin designed for pregnant women.

Renate is intended to “aid renal function in cats.” It contains:

calcium carbonate
magnesium carbonate
curcumin
cranberry
pine bark extracts
B vitamins
vitamin E

It comes in a 2mg sachet and the dosage is one sachet a day, divided between all that day’s meals. I am trying to find out how much calcium carbonate that contains.

I do not recommend cranberry for CKD cats, nor would I want to give curcumin.

Calcium-based Binders Side Effects

Hypercalcemia in cats (2001) Chew D Presentation to the World Small Animal Veterinary Association World Congress 2001 mentions that using calcium-based binders may cause hypercalcaemia. Thus, if you are using a calcium-based binder, frequent monitoring of blood calcium levels is essential.

Chronic kidney disease (CKD) in dogs and cats — staging and management strategies (2015) Chew D A Presentation to the Virginia Veterinary Medical Association 2015 Virginia Veterinary Conference states that “Calcium carbonate binds phosphorous best in an acidic environment (pH approx. 5) and binding capacity is reduced in the neutral pH range. Many CKD patients receive inhibitors of gastric acid secretion potentially reducing calcium carbonates ability to bind phosphorous.” I did use calcium-based binders and famotidine with Ollie with no problems, but if you are using products such as famotidine (Pepcid AC) or omeprazole (Prilosec), I would discuss with your vet as appropriate.

The role of phosphorus in feline chronic renal disease (2010) Chew D & Kidder AC CVC in San Diego Proceedings says that cats on calcitriol should not be given calcium-based phosphorus binders.

Effects of phosphorus binders in moderate CKD (2012) Block GA, Wheeler DC, Persky MS, Kestenbaum B, Ketteler M, Spiegel DM, Allison MA, Asplin J, Smits G, Hoofnagle AN, Kooienga L, Thadhani R, Mannstadt M, Wolf M & Chertow GM Journal of the American Society of Nephrology 23(8) pp1407-15 found that binders containing calcium acetate did reduce phosphorus levels but also caused calcium build up in blood vessels, which may lead to heart problems.

Sevelamer-based Binders

There are two types of sevelamer-based binders, sevelamer hydrochloride and sevelamer carbonate. Sevelamer-based binders are very expensive, but may be worth considering if you cannot use the other types of binder for some reason, though there is little evidence for their use in cats. Chronic kidney disease (CKD) in dogs and cats – staging and management strategies (2015) Chew D Presentation to the Virginia Veterinary Medical Association 2015 Virginia Veterinary Conference says “Many human clinical studies have demonstrated the ability of sevelamer hydrochloride to lower serum phosphorous, and parathyroid hormone levels, and control Ca x P product in dialysis patients compared with calcium containing phosphate binders. Their effects on dogs and cats with clinical CRF, however, have not been reported.”

Comparison of sevelamer hydrochloride and sevelamer carbonate: risk of metabolic acidosis and clinical implications (2009) Pai AB & Shepler BM Pharmacotherapy 29(5) pp554-61 found that sevelamer hydrochloride may increase the risk of metabolic acidosis, but that sevelamer carbonate did not appear to do so.

Renagel: Sevelamer Hydrochloride

Renagel (sevelamer hydrochloride) is a relatively new phosphorus binder approved for use in humans, with not much history of use in cats. Centerwatch has information on the approval of Renagel for use in the USA.

Renal disease in cats (2013) Gunn-Moore DA Crieff 2 Day Small Animal CPD Meeting pp125-144 says “Some clinicians have also used sevelamer hydrochloride, but anecdotally this appears less effective than lanthanum.”

Renvela: Sevelamer Carbonate

Renvela (sevelamer carbonate) is the next generation version of Renagel which contains a carbonate buffer. It is intended to help with bicarbonate levels.

A generic is also available.

Effects of phosphorus binders in moderate CKD (2012) Block GA, Wheeler DC, Persky MS, Kestenbaum B, Ketteler M, Spiegel DM, Allison MA, Asplin J, Smits G, Hoofnagle AN, Kooienga L, Thadhani R, Mannstadt M, Wolf M & Chertow GM Journal of the American Society of Nephrology 23(8) pp1407-15 found that binders containing sevelamer carbonate did reduce phosphorus levels but also caused calcium build up in blood vessels, which may lead to heart problems.

Sevelamer-based Binders Side Effects and Interactions

Sevelamer may cause constipation. Another more worrying problem is interference with blood clotting, so if you use it, it may also be necessary to give your cat vitamin K. Speak to your vet about this.

Iron-Based Binders

Iron-based binders should not be used at the same time as aluminium hydroxide (see above).

Lenziaren

Lenziaren (also known as SBR759) is a phosphorus binder for cats derived from iron oxide. It has been available in Japan and Taiwan since 2013 and presumably Novartis, the manufacturer, will be releasing it in other markets in due course.

Efficacy, acceptability and tolerability of the new oral phosphate binder Lenziaren in healthy cats fed a standard diet (2014) King JN, Erasmus HL, Delport PC, Bester ICJ & Seewald W BMC Veterinary Research 10(258) found that Lenziaren seemed to be well tolerated when added to food. Iron levels also increased, as you might expect from an iron-based binder, but so did food intake. This trial was conducted in healthy cats, and found that when these healthy cats were given higher doses of Lenziaren, their phosphorus levels actually increased. The manufacturer is currently investigating this.

Like me, you may be wondering why Lenziaren was fed to healthy cats. This is probably because, according to Scientific opinion on the safety and efficacy of Lenziaren (iron, aqua carbonate hydroxyl oxo starch sucrose complex) as a feed additive for cats (2013) Panel on Additives and Products or Substances used in Animal Feed European Food Safety Authority Journal 11(5) p3204-5, Lenziaren is “intended to be used in food for adult cats to reduce phosphate absorption in the gastrointestinal tract in order to prevent chronic kidney disease.” Whilst phosphorus restriction may possibly be appropriate for older cats who may develop CKD in the near future (see Prevention), I would have thought feeding a somewhat lower phosphorus food would be a better first step. The panel concludes “Lenziaren has the potential to be efficacious in cats at the highest recommended dose of 1 g/cat per day (equivalent to 20 000 mg/kg feed). However, the FEEDAP Panel has some reservations regarding the value of its long-term use in healthy cats. The Panel concludes that there is a need for a post-market monitoring plan.” In a revised version of the scientific opionion, found here, the panel “considers that Lenziaren has the potential to be efficacious in binding intestinal phosphorus at the minimum recommended dose of 0.25 g/cat per day.”

Efficacy and acceptability of the new oral phosphate binder Lenziaren in healthy cats fed a renal diet (2015) King JN, Delport PC, Luus HG, Erasmus HL, Barnes PM & Speranza C Journal of Veterinary Pharmacology and Therapeutics 38(3) pp278–289 refers to earlier field trials which indicated that an effective dose for CKD cats was 0.5-2.0g per day, added to meals, and that, unlike the healthy cats in the above study whose phosphorus levels rose on higher doses, their phosphorus levels reduced at this dosage.

I have heard from a couple of people in those countries where Lenziaren is available who have used it in their CKD cats and found it effective. I think if I were to use it, I would monitor my cat’s iron levels as well as phosphorus.

Velphoro

Velphoro (sucroferric oxyhydroxide), previously known as PA21, is a newer binder which was launched in the USA in 2014 for humans on dialysis. It is also iron-based and comes in a chewable form. Apparently it binds phosphorus more effectively than sevelamer in human dialysis patients. The most common side effect is diarrhoea. I do not know anyone who has used it in cats as yet but will report further should that happen.

Naraquin

Naraquin contains a “proprietary blend” of calcium acetate, ferric citrate and chitosan plus other “supportive” ingredients. See above for more information.

Niacinamide (Vitamin B3)

Niacinamide (vitamin B3) is used by some people as a phosphorus binder. There is more information about the various B vitamins on the Vitamin B page.

What is Niacinamide?

Niacin is vitamin B3. In the body it may be converted into the active form, which is known as niacinamide or nicotinamide.

Vitamin B3 is important for processing lipids, amino acids and glucose within the body. A deficiency can affect appetite and red blood cell production. Vitamin B3 is an essential vitamin for cats, i.e. they cannot produce it within their bodies, so they must ingest it.

DSM has a rather technical overview of vitamin B3.

Niacinamide Mechanism

Niacinamide used as a binder has a somewhat different mechanism to other binders. Use of nicotinamide to treat hyperphosphatemia in dialysis patients (2013) Lenglet A, Liabeuf S, Guffroy P, Fournier A, Brazier M & Massy ZA Drugs in R&D 13(3) pp165-173 says “In vitro and in vivo data show that nicotinamide reduces hyperphosphatemia by inhibiting sodium-dependent phosphate co-transport in the renal proximal tubule and in the intestine. Accordingly, targeting the sodium-dependent phosphate co-transporter 2b by using nicotinamide as an alternative or adjunct to classical phosphate binders may be a therapeutic option for modulating serum phosphate in CKD.”

This basically means that niacinamide is not a binder in that it does not bind with phosphorus in food, but rather blocks systems that allow phosphorus to be absorbed within the intestines and kidneys. Therefore it is not necessary to give it with every meal.

Niacinamide Formulations

Vitamin B3 is widely available as either niacin (nicotinic acid) or as niacinamide (nicotinamide), either by itself or as part of a vitamin B complex product.

It is usually better to use niacinamide, particularly when giving higher doses. This is because giving niacin may lead to a niacin flush, which can cause tingling, itching and redness (unlikely to be visible in a cat) and headaches. Occasionally breathlessness may be seen. These symptoms usually only last an hour or so, but can be unpleasant. A niacin flush is more common with higher doses or when the vitamin is taken on an empty stomach. It may still happen when using niacinamide at higher doses, but is much less likely.

Niacin flushes usually stop as the body gets used to the medication.

PhosFix

PhosFix is a binder based on niacinamide and chitosan. Walmart has some information about it. PhosFix contains:

550g of niacinamide, which is a high dose (see below).
chitosan, commonly used as an oral adsorbent, which is intended to help reduce uraemic toxins.
fructooligosaccharides (FOS), presumably for their prebiotic properties, but not normally recommended for CKD cats
inulin, a prebiotic

Niacinamide Research

There has been some research in humans into the use of niacinamide to control phosphorus levels in CKD patients, usually patients receiving dialysis (which very few cats are given). I am not aware of any research into the use of vitamin B3 in cats. The following studies relate to humans.

Niacin as a potential treatment for dyslipidemia and hyperphosphatemia associated with chronic renal failure: the need for clinical trials (2010) Ahmed MH Renal Failure pp642-646 says “Niacin has been shown to increase fecal phosphate excretion but not urinary phosphate excretion. Its basic mechanism of action lies on the inhibition of activity of expression of the sodium-phosphate cotransporter protein (Na–Pi–2b) at the duodenum and jejunum (this accounts for approximately 50% of gastrointestinal phosphate absorption).”

A randomized double-blind placebo-controlled trial of niacinamide for reduction of phosphorus in hemodialysis patients (2008) Cheng SC, Young DO, Huang Y, Delmez JA & Coyne DW Clinical Journal of the American Society for Nephrology 3(4) pp1131–1138 found that vitamin B3 helped reduce phosphorus levels, though the patients did continue to receive standard phosphorus binders during the trial as well, so it is not clear how much of the reduction could be attributed to niacinamide.

Another trial in human patients on dialysis, The effect of niacin on serum phosphorus levels in dialysis patients (2012) Edalat-Nejad M, Zameni F & Talaiei A Indian Journal of Nephrology 22(3) pp174–178, also looked at using niacin in addition to other binders. It states “The main troublesome constraint in our study was the erratic changes in phosphorus values caused by food variety. Although, we had a dietician on hand to counsel patients almost throughout the study period, the influence of food variety effect is irrefutable especially because of the short duration of the study. Conclusions Our study suggests niacin may emerge as a safe, low-cost therapy in combination with other phosphate binders for phosphate control. The modest increase in HDL values may be another beneficial effect of this treatment. However, larger and longer term controlled trials are needed to establish the optimal dosage and the clinical significance of niacin treatment.”

There was a fall in platelet counts in both these studies, though not a major one.

Later trials did give niacin supplements without using additional binders. Initially the doses given were high. Safety and effectiveness of nicotinic acid in the management of patients with chronic renal disease and hyperlipdemia associated to hyperphosphatemia (2008) Restrepo Valencia CA & Cruz JA Nefrologia 28(1) pp61-66 gave human patients 500mg of a slow release form of nicotinic acid daily, gradually increasing over three months to 1000mg daily. This appeared to be tolerated by the patients.

In Safety and efficacy of nicotinamide in the management of hyperphosphatemia in patients in hemodialysis (2011) Vasantha J, Soundararajan P, Vanitharani N, Kannan G, Thennarasu P, Neenu G & Umamaheswara Reddy C Indian Journal of Nephrology 21(4) pp245–249, human patients receiving dialysis were given 250mg of nicotinamide twice daily if their phosphorus level was over 5 mg/dl, and three times daily if their phosphorus level was over 8 mg/dl, in both cases for eight weeks. The study states “A statistically significant decrease of mean serum phosphorus was found at the 4th and at the end of 8th week of nicotinamide therapy,” and also says “There was a slight decrease in mean creatinine and BUN levels, which was not statistically significant.”

Effects of low-dose niacin on dyslipdemia and serum phosphorus in patients with chronic kidney disease (2013) Kang HJ, Kim DK, Lee SM, Kim KH, Han SH, Kim KH, Kim SE, Son YK & An WS Kidney Research and Clinical Practice 32(1) pp21-26 looked at human patients who took 500mg of niacin daily for six months. It states “In the niacin group, phosphorous level (P<0.05) was significantly decreased, and glomerular filtration rate (GFR) was significantly increased (P<0.05) at 24 weeks compared with baseline values.”

Effect of low dose nicotinic acid on hyperphosphatemia in patients with end stage renal disease (2016) Zahed NS, Zamanifar N & Nikbakht H Indian Journal of Nephrology 26(4) pp239–243 used lower doses and still found them effective. They gave human patients 25mg/day of niacin for 12 weeks; if patients failed to respond (phosphorus did not fall below 5.5 mg/dl), the dose was increased up to 50 mg/day after four weeks and 100mg/day after eight weeks. The study found that “Niacin 100 mg/daily decreased phosphorus serum levels and increased HDL serum levels in patients with ESRD that undergo dialysis.”

Use of nicotinamide to treat hyperphosphatemia in dialysis patients (2013) Lenglet A, Liabeuf S, Guffroy P, Fournier A, Brazier M & Massy ZA Drugs in R&D 13(3) pp165-173 says “Several recent clinical studies have explored the potential value of nicotinamide in phosphate control (as well as its effects on lipid levels) in dialysis patients. However, we consider that more data on pharmacodynamics, pharmacokinetics and safety are needed before this compound can be recommended as a treatment for hyperphosphatemia in ESRD patients.”

Fibroblast growth factor (FGF-23) is important for the regulation of phosphorus levels in the body. FGF-23 levels may in fact rise before other signs of CKD appear, and this also appears to happen in cats, with such increases being identified before any changes in PTH and phosphorus levels. Effect of niacin on FGF23 concentration in chronic kidney disease (2014) Rao M, Steffes M, Bostom A & Ix JH American Journal of Nephrology 39(6) pp484-490 found that in human patients “extended release niacin alone, but not in combination with laropiprant, lowered FGF23 and PTH concentrations. If confirmed, niacin may provide a novel strategy to decrease phosphorus, FGF23, and PTH concentrations in patients with CKD.”

However, Effects of nicotinamide and lathanum carbonate on serum phosphate and fibroblast growpth factor-23 in CKD: the COMBINE trial (2019) Ix JH, Isakova T, Larive B, Raphael KL, Raj DS, Cheung AK, Sprague SM, Fried LM, Gassman JJ, Middleton JP, Flessner MF, Block GA & Wolf M Journal of the American Society of Nephrology 30(6) pp1096-1108 looked at the effects of lanthanum carbonate and/or niacinamide as a phosphorus binder in human patients and found “LC and/or NAM treatment did not significantly lower serum phosphate or FGF23 in stage 3b/4 CKD over 12 months. Although these agents appeared safe, intestinal symptoms limited adherence.”

In early 2013 several members of my support group began using niacinamide in their CKD cats after consultation with their vets. None of them continued to use it in this way as far as I know, but unfortunately none of them reported back on their experiences so I do not know for sure, and if they did stop using it, I don’t know why. Having said that, another member started using niacinamide at a later date and used it for over a year, finding it very effective as a binder and with no real side effects. Other group members are currently using niacinamide with no complaints. One member has found it to be the only binder that worked for her two cats’ obstinately high phosphorus levels.

Niacinamide Side Effects

Niacinamide is thought to be less likely to cause side effects than niacin, but they may still occur. See above for information on the niacin flush.

Other possible side effects include upset stomach, reduced appetite and dizziness.

In humans, more serious side effects have been seen with doses of over 3g of niacin per day, including increased liver enzymes, high blood sugar levels, stomach ulcers, irregular heart beat and even blindness.

Diabetes is also a possible concern with long term use, because blood sugar levels may increase, requiring an adjustment of insulin if your cat is on this.

Dr Larry Nagode, formerly of Ohio State University College of Veterinary Medicine, has stated that niacin and niacinamide may increase calcium levels.

Safety and efficacy of nicotinamide in the management of hyperphosphatemia in patients in hemodialysis (2011) Vasantha J, Soundararajan P, Vanitharani N, Kannan G, Thennarasu P, Neenu G & Umamaheswara Reddy C Indian Journal of Nephrology 21(4) pp245–249 states in respect of the human patients in the study “Regarding the adverse drug reactions of nicotinamide, watery stools were reported in seven patients and it resolved on continuation of therapy not requiring any dosage adjustment or therapy with other drugs. Thrombocytopenia that is commonly associated with niacinamide and nicotinic acid therapy was not reported by any of the patients. Other than alkaline phosphatase levels all the liver function tests were normal. Blood sugar levels were also not affected by nicotinamide therapy.”

There has been some debate about the possibility of niacin increasing the risk of stroke in people. Extended-release niacin therapy and risk of ischemic stroke in patients with cardiovascular disease (2013) Teo KK, Goldstein LB, Chaitman BR, Grant S, Weintraub WS, Anderson DC, Sila CA, Cruz-Flores S, Padley RJ, Kostuk WJ, Boden WE and on behalf of the AIM-HIGH Investigators Stroke 44 pp2688-2693 looked at the use of niacin in addition to other heart medicine in humans with known heart disease. Initial results in this trial indicated an increased risk of stroke in patients taking extended release niacin, but the final report states “Although there was a numeric excess in ischemic strokes associated with the addition of niacin to simvastatin, the number of events was small, and multivariate analysis accounting for known risk factors did not support a significant association between niacin and ischemic stroke risk.”

Drugs has some information about niacin side effects.

Unfortunately, there is no one perfect dosing schedule: it depends upon your cat’s phosphorus level, stage of CKD, the type of food your cat eats and how well s/he responds to binders. Therefore there are a number of recommended dosage protocols, that fall into three categories:

ISFM consensus guidelines on the diagnosis and management of feline chronic kidney disease (2016) Sparkes AH, Caney S, Chalhoub S, Elliott J, Finch N, Gajanayake I, Langston C, Lefebvre H, White J & Quimby J Journal of Feline Medicine and Surgery 18 pp219-239 simply give a dosage range.
Dr Larry Nagode (formerly of Ohio State University College of Veterinary Medicine, now sadly deceased). Recommended dosage varies depending upon your cat’s current phosphorus level.
IRIS treatment recommendations for CKD in cats (2023) International Renal Interest Society look at both your cat’s existing phosphorus level and your cat’s creatinine level. This is because IRIS accepts that the more advanced the CKD is (as indicated by the creatinine level), the harder it can be to reduce your cat’s phosphorus levels. Their recommendations are as follows and apply to aluminium hydroxide, calcium acetate, calcium carbonate and lanthanum:

International Renal Interest Society Dosage Guidelines

USA

Stage of CKD (IRIS)	Creatinine Level (mg/dl)	Current Phosphorus Level mg/dl	Binder Dosage
Stage 2	Between 1.6 and 2.8	Above 4.6	14-28 mg per lb of cat per day
Stage 3	Between 2.9 and 5.0	Above 5.0	14-28 mg per lb of cat per day
Stage 4	Over 5.0	Above 6.0	14-28 mg per lb of cat per day

International

Stage of CKD (IRIS)	Creatinine Level (mmol/L)	Current Phosphorus Level (mmol/l)	Binder Dosage
Stage 2	Between 140 and 249	Above 1.5	30-60 mg per kg of cat per day
Stage 3	Between 250 and 439	Above 1.6	30-60 mg per kg of cat per day
Stage 4	Over 440	Above 1.9	30-60 mg per kg of cat per day

As you can see, the IRIS recommended amounts of binder are actually the same for every stage. What is different is:

firstly, when you start treating for high phosphorus levels. For example, for a cat in IRIS Stage 2 you would start treating a phosphorus level above 4.6 mg/dl or 1.5 mmol/L international, whereas for a cat in Stage 3, a level above 4.6 mg/dl (1.6 mmol/L international) would be acceptable as long as it was no higher than 5 mg/dl (1.9 mmol/L international).
secondly, the target phosphorus level for each stage of CKD. Basically you want it below the level at which you start binders, so for example, for a cat in Stage 2 you want the phosphorus level below 4.6 mg/dl or 1.5 mmol/L (international).

It is usually best to start at the lower recommended levels, increasing the dose only if your cat’s blood phosphorus levels do not reduce, but be guided by your vet. See The Importance of Phosphorus Control for more information on your phosphorus goals.

In 2023 the International Renal Interest Society issued further guidelines following the introduction of a new test for a renal biomarker called fibroblast growth factor 23 (FGF-23) in 2022, as follows:

if the cat’s phosphorus level is in the target range for the relevant stage of CKD and FGF-23 is below 500 pg/ml, this indicates excellent control, i.e. your current dosage is working.
However, if FGF-23 is over 700 pg/ml, you may need to increase the dose or add another binder, as long as the cat does not have high calcium levels, severe anaemia or an inflammatory disease (these may be contributing to the increase in FGF-23).

People used to be confused that the dosage of phosphorus binder recommended did not take into account the size of the meal being consumed. Specialists such as Dr Chew in Chronic kidney disease (CKD) in dogs and cats – staging and management strategies (2015) A Presentation to the Virginia Veterinary Medical Association 2015 Virginia Veterinary Conference are now advising that “The dose of any phosphate binder should be based on the meal size (phosphorus intake) and the prevailing serum phosphorus level for each CKD patient; the dose is titrated to effect.” Obviously this is the ideal, so if you know, for example, that your cat always eats larger meals in the evening than in the morning, you can adjust the dose accordingly.

Aluminium Hydroxide and Calcium Carbonate Dosage Recommendations

These dosages relate to over the counter aluminium hydroxide or calcium carbonate products. If you are using one of the calcium carbonate branded products discussed above, follow the manufacturer’s recommendations after discussion with your vet.

Recommendation		Cat Weight
Source	Total Daily Dosage per kg of cat*	5 lb 2.27 kg	7.5 lbs 3.4 kg	10 lb 4.5 kg	12.5 lbs 5.7kg
IRIS	30-60 mg	68-136 mg	102-204 mg	135-270 mg	170 – 340 mg
ISFM**	90 mg	204 mg	306 mg	405 mg	513 mg
Dr Nagode	50-200 mg	113-450 mg	170-680 mg	225-900mg	285 – 1140 mg
Total Range	30-200 mg	68-450 mg	102-680 mg	135-900mg	170 – 1140 mg

*A kg is 2.2 lbs

**These are starting dosages, and can be increased if they are not sufficient to reduce your cat’s blood phosphorus levels

Here is what I would probably try myself. However, this is just my opinion, and if your vet recommends a different dosage regimen, you should of course follow your vet’s advice:

Cat’s Phosphorus Level mg/dl	Cat’s Phosphorus Level mmol/L	Possible Starting Daily Dose
Below 6	Below 1.9	30 mg per kg of cat 14 mg per lb of cat
Between 6 and 7	Between 1.9 and 2.25	60 mg per kg of cat 27 mg per lb of cat
Above 7	Above 2.25	90 mg per kg of cat 40 mg per lb of cat

I would not give more than 100 mg per kg of cat per day (50 mg per lb of cat per day) of aluminium hydroxide (i.e. heading into Dr Nagode’s recommendations) without detailed discussions with your vet. It is probably safe, and certainly many members of Tanya’s CKD Support Group have used such amounts with no problems; but you need to balance the potential benefits against the possible risks, including the rare possibility of aluminium toxicity.

If your cat needs large amounts of binder, it may be safer to use a smaller amount of aluminium hydroxide together with another binder, such as lanthanum carbonate. See below for information on combining binders.

Remember, the amounts given are the total daily dosage. The total amount should be divided among as many of your cat’s daily meals as possible, ideally with larger meals receiving a larger proportion of the daily dose (see Mixing with Food below).

See below for how to give binders, including how to mix them with your cat’s food.

Measuring Aluminium Hydroxide

Aluminium hydroxide does not have to be measured too precisely, but as a rough guide:

Brand	Amount	Contains approximately
Thriving Pets (powdered) and some compounding pharmacies	Half a teaspoon, loosely packed	600 mg
Phos-Bind* 200g (powdered):	One level scoop (scoop comes with the product and contains around a quarter of a teaspoon)	500 mg
Phos-Bind* 35g (powdered)	One level scoop (scoop comes with the product and contains around an eighth of a teaspoon)	250 mg
Liquid e.g. AlternaGel	One teaspoon	600 mg

Calcium Acetate Dosage Recommendations

The calcium acetates (e.g. PhosLo) bind 2-3 times as much phosphorus as calcium carbonate (e.g. Tums). On the other hand, they are more likely to cause elevated calcium levels in the blood (hypercalcaemia). They also do not bind as much phosphorus as aluminium hydroxide or lanthanum carbonate binders.

Recommendation		Cat Weight
Source	Total Daily Dosage per kg of cat*	5 lb 2.27 kg	7.5 lbs 3.4 kg	10 lb 4.5 kg	12.5 lbs 5.7kg
IRIS	30 – 60 mg	68 – 136 mg	102 – 204 mg	135 – 270 mg	170 – 340 mg
ISFM**	60 – 90 mg	136 – 204 mg	204 – 306 mg	270 – 405 mg	340 – 513 mg
Total Range	30 – 90 mg	68 – 204 mg	102 -306 mg	135 – 405mg	170 – 513 mg

*A kg is 2.2 lbs

**These are starting dosages, and can be increased if they are not sufficient to reduce your cat’s blood phosphorus levels

See below for how to give binders, including how to mix them with your cat’s food.

Lanthanum Carbonate Dosage Recommendations

Recommendation		Cat Weight
Source	Total Daily Dosage per kg of cat*	5 lb 2.27 kg	7.5 lbs 3.4 kg	10 lb 4.5 kg	12.5 lbs 5.7kg
IRIS	30 – 60 mg	68 – 136 mg	102 – 204 mg	135 – 270 mg	170 – 340 mg
ISFM**	30 – 90 mg	68 – 204 mg	102 – 306 mg	135 – 405 mg	170 – 513 mg
Total Range	30 – 90 mg	68 – 204 mg	102 -306 mg	135 – 405mg	170 – 513 mg

*A kg is 2.2 lbs

**These are starting dosages, and can be increased if they are not sufficient to reduce your cat’s blood phosphorus levels

As you can see, lanthanum carbonate dosing is in principle the same as for aluminium hydroxide. So, for example, if you are giving 300mg of aluminium hydroxide a day but want to switch to Fosrenol, you would still need to give 300mg per day.

See below for how to give binders, including how to mix them with your cat’s food.

Nefrokrill Dosage

The manufacturer recommends one pearl a day if you are feeding a therapeutic kidney diet and two pearls a day if you are feeding another commercial food or a homemade food.

Sevelamer-based Binders Dosage Guidelines

Recommendation		Cat Weight
Source	Total Daily Dosage per kg of cat*	5 lb 2.27 kg	7.5 lbs 3.4 kg	10 lb 4.5 kg	12.5 lbs 5.7kg
ISFM**	90 – 160 mg	204 – 363 mg	306 – 544 mg	405 – 720 mg	513 – 912 mg

*A kg is 2.2 lbs

**These are starting dosages, and can be increased if they are not sufficient to reduce your cat’s blood phosphorus levels

See below for how to give binders, including how to mix them with your cat’s food.

Iron-Based Binders Dosage Guidelines

Recommendation		Cat Weight
Source	Total Daily Dosage per kg of cat*	5 lb 2.27 kg	7.5 lbs 3.4 kg	10 lb 4.5 kg	12.5 lbs 5.7kg
ISFM**	0.25 – 0.5 g	0.5675 – 1.135 g	0.85 – 1.7 g	1.125 – 2.25 g	1.425 – 2.85 g

*A kg is 2.2 lbs

**These are starting dosages, and can be increased if they are not sufficient to reduce your cat’s blood phosphorus levels

See below for how to give binders, including how to mix them with your cat’s food.

Lenziaren Guidelines

Scientific opinion on the safety and efficacy of Lenziaren (iron, aqua carbonate hydroxyl oxo starch sucrose complex) as a feed additive for cats (2013) Panel on Additives and Products or Substances used in Animal Feed European Food Safety Authority Journal 11(5) p3204-5 states:

the minimum recommended dose of Lenziaren is 0.25g/cat per day
the highest recommended dose is 1 g/cat per day.

Niacinamide Binders Dosage Guidelines

The maximum safe dose for cats has never been assessed.

For general intake to maintain health in cats, Your cat’s nutritional needs (2006) National Research Council recommends that a 9 lb (4 kg) healthy cat eating 250 calories per day should receive a total intake of 2.5mg of vitamin B3 a day.

Nutritional management of renal disease (2008) Sturgess K Presentation to the World Small Animal Veterinary Association World Congress suggests that a CKD cat should receive 3.6-7.2mg a day. This is total intake, i.e. it includes vitamin B in food.

In the above studies into the use of niacin to control phosphorus levels in humans, widely varying doses were used, so it can be difficult to know the optimum dose for a human, let alone a cat.

Members of Tanya’s CKD Support Group who used niacinamide to control phosphorus levels in 2013 began with 50mg of niacinamide.

Some of them then gradually increased the dosage to 80-100mg daily. It is best to start low and increase gradually in order to avoid possible side effects, such as loss of appetite or diarrhoea.

I have also heard from people who are giving 250mg once or twice a day. This is based on a suggestion from Dr Mandelker, a vet posting on the Veterinary Information Network. He has kindly confirmed to me that he has used this dosing schedule, and believes niacinamide is a safe binder, but he did mention it is not as effective as aluminium hydroxide.

I would not give vitamin B3 to your cat without discussing a suitable dose with your vet first. Since vitamin B3 may cause a niacin flush, it is important to start low and increase the dose slowly.

Niacinamide often tastes bitter, so it is probably best to give it in a gelatin capsule.

Adjusting the Dosage

Your cat’s blood phosphorus levels should start falling 7-10 days after starting a phosphorus binder. Your vet should check your cat’s blood phosphorus levels 10-14 days after starting a binder. If your cat’s blood phosphorus level is not falling, you should discuss increasing the dose you are using with your vet. If the phosphorus level seems to be falling, I would continue with the dosage you are using.

You will normally need to continue with binders once you have started them.

See Monitoring Phosphorus Levels for more information.

Combining Binders

If you are having trouble getting phosphorus under control using one type of binder alone, you can use another in addition to the first. The adequacy of phosphorus binder prescriptions among American hemodialysis patients (2012) Huml AM, Sullivan CM, Leon JB & Sehgal AR Renal Failure 34(10) pp1258–1263 says that human patients with CKD often need to use more than one phosphorus binder.

This may also apply to cats, and mixing binders may help avoid possible problems that may arise from using only one type of binder. IRIS treatment recommendations for CKD in cats (2023) International Renal Interest Society state “Hypercalcemia should be avoided — combinations of aluminum and calcium phosphate containing binders may be necesary in some cases.”

If you do not wish to give higher doses of aluminium hydroxide-based binders, you might choose to add lanthanum carbonate. You would give the lower doses of aluminium hydroxide outlined above and then add lanthanum carbonate. A suitable starting dose of lanthanum carbonate might be 50-100mg per kg of cat per day, which equates to a bit less than 25-50 mg per lb of cat per day. You can go up to 200mg per kg of cat per day (just under 100mg per lb of cat per day) if necessary, but obviously work with your vet on determining the most appropriate dosage for your cat.

Fosrenol insert leaflet says “There is a potential for Fosrenol to interact with compounds that bind to cationic antacids (i.e., aluminum-, magnesium-, or calcium-based); therefore, do not take such compounds within 2 hours of dosing with Fosrenol.” Therefore, although some people do use both lanthanum and aluminium hydroxide binders, it is probably wiser to give them at separate times of the day.

How to Give Binders

See above for recommended dosages.

When to Mix Binders with Food

Phosphorus binders (apart from niacinamide) must be given with food so they can bind with the phosphorus in it. Chronic kidney disease (CKD) in dogs and cats – staging and management strategies (2015) Chew D A Presentation to the Virginia Veterinary Medical Association 2015 Virginia Veterinary Conference says “Intestinal phosphate binders work best when given with meals or within 2 hours of feeding to maximize their binding of dietary phosphorus.”

Personally, I think within two hours of feeding is pushing it. One human study, Effectiveness of aluminum hydroxide timing administration in relation to meals in controlling hyperphosphatemia in dialysis patients (2005) Katopodis KP, Andrikos E, Pappas M & Siamopoulos KC The International Journal of Artificial Organs 28(8) pp803-7, found that giving aluminium hydroxide binders 30 minutes before eating only reduced phosphorus levels by 7%, whereas administering them mixed with food or up to 30 minutes after the meal reduced phosphorus levels by 28.5%.

I would aim to give the binders as close to feeding times as possible and check your cat’s blood phosphorus levels after about two weeks, when with luck they will be falling nicely.

How to Mix Binders with Food

Aluminium hydroxide and many other binders are usually odourless and tasteless if you choose carefully, though they can sometimes add a bit of a gritty texture to food or make it taste a little drier.

Most people find it easiest to add the binders to the cat’s food, though if the manufacturer of your binder makes a different recommendation, be guided by that.

Giving Binders with Canned Food

tablets can simply be crushed and added to the food.

capsules can be opened and the contents mixed with the food (after measuring as necessary).
liquid binders can either be mixed in the food or syringed into your cat’s mouth just before eating.
one retailer recommends adding a teaspoon of water to the tinned food and binder and letting it stand for ten minutes before serving in order to let the binder mix thoroughly. This may help remove any grittiness.

Giving Binders with Dry Food

try putting the food in a freezer bag together with the crushed or powder binder and leave them to mingle overnight.
if you are using a liquid binder, you can syringe it into your cat’s mouth just before eating.

How Long For Binders to Work

You should see an improvement in your cat’s blood phosphorus levels after 7-10 days. You may see a difference in your cat’s demeanour sooner than this. Check your cat’s phosphorus level every two weeks until the level is acceptable, then check it every 2-3 months to see if any adjustments to your treatment plan are necessary.

Please see The Importance of Phosphorus Control for information on your phosphorus goal and how to monitor your cat’s phosphorus levels.

How Long to Give Binders

I am often asked if you should stop using a binder or adjust the dosage once your cat’s blood phosphorus has fallen to a satisfactory level. Normally you will need to continue with the binder. In most cases, you will need to continue with the dosage that reduced your cat’s blood phosphorus levels to your target level, but you can of course speak to your vet about adjusting the dose, either upwards or downwards, if necessary, e.g. if your cat’s CKD starts to worsen and phosphorus levels start to rise again.

Monitoring Phosphorus Levels

In theory, a cat receiving binders may develop the opposite of what you are trying to treat, i.e. low phosphorus levels (hypophosphataemia). Chronic kidney disease (CKD) in dogs and cats – staging and management strategies (2015) Chew D A Presentation to the Virginia Veterinary Medical Association 2015 Virginia Veterinary Conference, Dr D Chew states “it is difficult for this to develop in those with initially high concentrations of serum phosphorus.” However, in Renal disease in cats (2013) Crieff 2 Day Small Animal CPD Meeting pp125-144 Prof D Gunn-Moore says “Since hypophosphataemia can result in weakness and anaemia, it is important to monitor phosphate levels whichever type of phosphate binder is chosen.”

Please see The Importance of Phosphorus Control for information on your phosphorus goal and how to monitor your cat’s phosphorus levels.

How to Manage with Multicat Households

Try not to let your non-CKD cats eat food containing phosphorus binders. This is particularly important for kittens, who need twice as much phosphorus each day as a healthy cat because they are still growing.

However, if your healthy adult cats eat a small amount of food containing binders occasionally (say once or twice a week), this should not be a problem as long as you make sure that most of the food they eat does not contain binders.

If you have to go to work each day and do not want to separate your cats, one possible solution might be to leave out therapeutic kidney dry food for all your cats to eat, but to give your healthy cats normal food the rest of the time. Be guided by your vet.

Where to Buy Phosphorus Binders

Please read above about which binder to use and why.

If you buy aluminium hydroxide, you may see an expiration date on it. This is usually to comply with pharmacy laws, but in practice, since aluminium hydroxide is a mineral that is mined from the earth, it cannot really expire, so I would not worry too much about expiry dates.

Be careful about your source for aluminium hydroxide. Some people try to buy products that are not pharmaceutical grade, often from ebay. These are not pure enough and are not suitable for CKD cats.

Sources USA

Aluminium Hydroxide USA

Rugby make a liquid aluminium hydroxide product which you may come across on various websites, but unfortunately it is mint flavoured according to the US National Library of Medicine, which most cats (apart from my Indie) don’t like.

Loose Aluminium Hydroxide

Loose aluminium hydroxide in gel or powder form is a popular choice because it is odourless and tasteless, so is much easier to give. There are three main generic brands available, Spectrum, Gallipot and PCCA.

Loose aluminium hydroxide used to be available in tubs from a number of online pharmacies, but the only one which definitely still sells it these days is Thriving Pets. Most local compounding pharmacies should be able to order it for you, which may take a few days; it is fine to wait that long. You may be told that a prescription is required, but this is not correct, the gel and powder formulations are over the counter products.

Thriving Pets sells 200g (about 8 oz) of aluminium hydroxide dry gel for US$59.95 plus shipping. They also sell 50g (a little under 2 oz) of aluminium hydroxide for US$18.95.

Thriving Pets also sells aluminium hydroxide capsules in various sizes, but these require a prescription, which the other formulations do not:

If you enter the word “tanya” (without the “) in the promotional code box, you will receive a US$5 discount on orders over US$100.

Phos-Bind

Phos-Bind is a brand of loose aluminium hydroxide binder made by Rx Vitamins. It is available as follows (as at 2025):

200g size (just over 7 ounces) with a scoop that contains approximately 500mg of aluminium hydroxide.
35g size (just over 1 ounce) with a smaller scoop that contains approximately 250mg of aluminium hydroxide.

VetRxDirect sells 200g for US$37.80 or 35g for US$19.80, with free shipping on orders over US$49, shipping costs US$4.99 for orders below this.

PureFormulas sell 200g of Phos-Bind for US$53.59 with free shipping.

AlternaGel or Amphojel

If you buy your binders from your vet, you will often be offered an aluminium hydroxide-based binder called AlternaGel, but this is peppermint flavoured, which most cats hate. AlternaGel also contains potassium citrate.

Amphojel, another product which vets sometimes stock, comes in both unflavoured and peppermint flavoured version, so check before you buy that you will be getting the unflavoured one; most vets only seem to stock the peppermint-flavoured version.

Epakitin USA

Entirely Pets

Sells Epakitin for US$33.99 (60g), US$79.99 (180g) or US110.99 (300g).

Sources UK

Aluminium Hydroxide UK

Hyperdrug sells 30g of aluminium hydroxide powder for £23.99 with free shipping over £49, otherwise shipping costs £4.50. It comes with a scoop and one level scoop apparently holds 930mg of aluminium hydroxide, which sounds like rather a lot to me.

Bova UK is a veterinary specials manufacturer that sells 50ml bottles of a 100mg per 1ml chicken-flavoured suspension. This can only be ordered by your vet, and the price will be set by your vet, with an added mark up. One person was charged £48 plus £5 for shipping, but in April 2025 another person was charged £117.

US Sellers

If you import goods costing over £15 into the UK, you are liable for VAT on the total cost of the order, including shipping costs. This can hold up your order, because Royal Mail in particular will not deliver the goods until you have paid any taxes and duty due.

Thriving Pets in the USA will ship to the UK. See above for prices. You will also have to pay a customs paperwork fee of around US$10. Shipping should take 1-2 weeks.

If you enter the word “tanya” (without the “) in the promotional code box, you will receive a US$5 discount on orders over US$100 (before shipping and other costs).

Storkz in the USA sells Phos-Bind (35g) for £44.59 plus shipping costs (which can be high). It takes about 2-3 weeks to arrive.

PureFormulas sell 200g of Phos-Bind for US$53.59 and will ship to a number of other countries.

Ipakitine UK

This is usually available from local vets and Amazon.

Vet Pharmacy sells Ipakitine for £18.90 for 60g.

VioVet sells Ipakitine for £23.50 for 60g or £59.99 for 180g.

Niacinamide UK

Amazon sells a powder form that some members of Tanya’s CKD Support Group have used.

Sources Canada

Aluminium Hydroxide Canada

Pets Drug Mart sells Phos-Bind for CAN$35.95 for 35g. No prescription is required.

Sources Europe

Aluminium Hydroxide Europe

If you live in a country where compounding is available, most compounding pharmacies will be able to assist you.

Ipakitine Europe

This is widely available in most European countries, from vets, online pet supply stores or Amazon.

Sources Australia

Alu-Tabs, made by iNova Pharmaceuticals, are probably your best bet. They come in 600mg tablets rather than a powder, so you will need to crush them. They should be available over the counter in pharmacies, though your pharmacist may not realise they are there. Don’t say they are for a cat, or they may ask for a prescription from your vet, whereas if you buy them for your own indigestion, they are over the counter.

Healthy Life sells 100 Alu-Tabs for AUS$25.59.

Home Pharmacy sells 100 Alu-Tabs for AUS$31.39.

Pet Chemist Sells 100 Alu-Tabs for more than double the cost, at AUS$68.95. Pet Chemist also sells Ipakitine.

This page last updated: 13 June 2025

Links on this page last checked: 19 May 2025