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.
Keeping phosphorus levels under control should help slow the progression of the CKD,
reduce the risk of serious problems (including heart 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 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.
On the left is a list of this page's 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 CKD cat can no longer
efficiently excrete excess phosphorus, 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. High phosphorus
levels:
make
the cat feel unwell
cause
CKD progression
cause an unpleasant complication of CKD
called secondary hyperparathyroidism
The first line of
phosphorus control 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 Practice41(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.
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 (over6 mg/dl (US) or 1.9 mmol/L
(international)), 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 ACVC 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." In this situation,
you will probably have to consider the addition of phosphorus binders.
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 reduces the levels of phosphorus in the cat's body.
To be effective, phosphorus binders must be given shortly before or 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 in the
food, so your cat will still be absorbing some of the phosphorus in the
food. Therefore, if you do have to feed a non-therapeutic kidney food (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
Diet and Nutrition section has links to food data tables for you to
check out the phosphorus levels of various cat foods. I'm 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 Surgery22 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."
If you cannot persuade your cat to eat a therapeutic
kidney
diet, or if despite feeding a therapeutic kidney diet for a month, your cat's blood phosphorus levels
are over6 mg/dl (US) or
1.9 mmol/L
(international), speak to your vet about adding binders.
If your cat isn't eating at all, there is little point giving
phosphorus binders because your cat isn't ingesting any phosphorus in the
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 if necessary.
Types of Phosphorus Binder
There are five main categories of phosphorus binders
based upon the primary binding ingredient:
Only three types are commonly used in cats: aluminium hydroxide, calcium
carbonate and lanthanum carbonate.
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 generally considered to be the best choice within this
family of medications.
This type of binder, as the name suggests, also contains magnesium.
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.
Pet Education
states "Do not use magnesium containing products in
animals with kidney failure."
Some British vets
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 Association52(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
This 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 (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.
Many vets are reluctant to prescribe aluminium-based binders because they
think cats
hate the taste. If they do prescribe them, they
often
prescribe
AlternaGel, a
peppermint-flavoured 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.
Fortunately, there are alternatives.
Conseal AlH are aluminium
hydroxide 200 mg chews made by Bock Pharma which some vets in the USA are
beginning to stock. They come in a box of 28
individually wrapped chews. The chews are semi-soft
so can be broken or cut into pieces. In this form they can be mixed with
food, but one member of
Tanya's CKD Support Group
found the chews very helpful for her cat who missed getting
treats, and gave them before her cat's meals. They could also be useful
for multi-cat households where you can give your CKD cat a Conseal treat
whilst giving your other cats ordinary treats.
Alternatively, it is probably easier and certainly cheaper to buy aluminium hydroxide binders
in a tasteless and odourless powder form, which
most cats do not seem to notice in their food. See
below for information on the various brands and
where to buy them, including links to mail order suppliers who can ship to
the UK, USA,
Canada and Australia. Contrary to what some vets and pharmacists seem to believe,
you do not need a prescription to buy these products.
Aluminium Hydroxide Dosage Recommendations
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, which fall into three
categories:
ISFM and Dr Chew simply give a dosage range.
Dr Nagode's recommended dosage varies depending upon your cat's current
phosphorus level.
The IRIS recommendations 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.
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 on your
phosphorus goals.
states "initially
is used at a dosage of 20-30 mg/kg q8h or 30-45 mg/kg q12h given with
food."
That is a
total of 60-90 mg/kg a day.
Dr Larry Nagode, formerly of Ohio State University College of
Veterinary Medicine
The following dosages were provided by Dr Larry Nagode, formerly of
Ohio State University College of Veterinary Medicine, now sadly
deceased.
USA
Current Phosphorus Level: mg/dl
Binder Dosage
Between 4.0 and 6.00
25 mg per lb of cat per day
Between 6.0 and 8.0
50 mg per lb of cat per day
Between 8.00 and 10.00
100 mg per lb of cat per day*
Over 10.00
Discuss with your vet
International
Current Phosphorus Level: µmol/L
Binder
Dosage
Between 1.3 and 1.9
50 mg per kg of cat per day
Between 1.9 and 2.6
100 mg per kg of cat per day
Between 2.6 and 3.25
200 mg per kg of cat per day*
Over 3.25
Discuss with your vet
*I would not give more than 50 mg per lb of cat per
day (100 mg per kg of cat per day) without detailed discussions with your
vet. It is probably safe, but you need to balance the potential benefits
against the possible risks, including the rare possibility of aluminium
toxicity - see below.
It may be safer to use a smaller amount of aluminium hydroxide together
with another binder, such as
lanthanum carbonate (Renalzin or Fosrenol).
As you
can see, the IRIS recommended amounts of binder are actually the
same for every stage. What is different is:
firstly,
when they suggest that you try to control high phosphorus levels. For example, for
a cat in IRIS Stage 2 you would treat 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 to be below 4.6 mg/dl
or 1.5 mmol/L international. See
Aluminium Hydroxide Dosage Calculations and Adjustments
I expect your head is spinning now! I know quite a few people get confused
by all these recommended dosages, so here is a summary, along with some
tips on how to choose or adjust the dosage..
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
Dr Chew
60-90 mg
136-204 mg
204-306 mg
270-405 mg
340 - 513 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
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.
Aluminium Hydroxide: Choosing a Dosage
The
ranges for how much to give are quite wide, so talk to your vet
about a suitable starting point for your cat. Many people successfully
follow Dr Nagode's recommendations
above, though these tend
to be higher than those of other experts, because recently there is a trend to be
more cautious with dosing in order to reduce the risk of
aluminium toxicity.
Taking
all the experts' recommendations above, 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 µmol/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
Aluminium Hydroxide: Adjusting a 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.
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.
Aluminium hydroxide does not have to be measured
too precisely, but as a rough guide:
Form of Aluminium Hydroxide
Quantity
Contains approximately
Powdered
Quarter of a teaspoon (1/4 tsp, ¼ tsp), loosely packed
300 mg of aluminium hydroxide
Liquid e.g. AlternaGel
One teaspoon
600mg of aluminium hydroxide
I used to have this table on the website, and have received so many
requests for it that I am including it again. Please note that the amounts
involved are so tiny that I have had to do quite a bit of rounding up or
down.
Cat Weight
Source
Total
Daily Dosage
per kg
5 lb
2.27 kg
7.5 lbs
3.4 kg
10 lb
4.5 kg
12.5 lbs
5.7kg
Dosage
mg
Dosage tsp
Dosage mg
Dosage tsp
Dosage mg
Dosage tsp
Dosage mg
Dosage tsp
IRIS
30-60 mg
68-135
1/16-1/9
102-204
1/12-1/6
135-270
1/8-1/4
170-340
1/8-1/4
Dr Chew
60-90 mg
135-204
1/9-1/6
204-306
1/6-1/4
270-405
1/4-1/3
340-513
1/4-2/5
ISFM*
90
204
1/6
306
1/4
405
1/3
513
2/5
Dr Nagode**
50-200 mg
113-450
1/9-3/8
170-680
1/8-1/2
225-900
1/6-3/4
285-1140
1/4-1.0
Total Range
30-200 mg
68-450
1/16-3/8
102-680
1/12-1/2
135-900
1/8-3/4
170-1140
3/4-1.0
* Starting dose
** Dr Nagode's recommendations vary depending upon the cat's initial blood
phosphorus level
Yep, these numbers are tiny and fiddly. I recommend that rather than
guessing and trying to measure tiny quantities, you buy a set of measuring
spoons which include a pinch (I think this may
be 1/16th), 1/8, 1/4, 1/2, 2/3 and 1 tsp for less than USD9 from
Amazon.
The same set costs £25.78 (spot the ripoff) from
Amazon UK. If you buy these, you can
simply scoop out the amount you need each day using the appropriate spoon.
If you can't get the spoons and need to measure it yourself, try this:
take a standard-sized teaspoon (the standard-sized teaspoon typically holds 5ml
of liquid).
Fill your teaspoon with aluminium hydroxide powder.
Then empty onto a dish and divide it as needed. For example, if you are
giving a quarter of a teaspoon (¼ of a tsp) a day, divide your pile into
four. You would then have four days worth of aluminium hydroxide treatment
on your dish.
If you look at the numbers above, you can see how many piles to divide
into. So for three eighths, divide it into eight and you would use three
of the eight portions. For one sixth, divide into six and use one portion
per day; and so on.
Remember, you won't give your daily dosage all in go. You will divide it
between your cat's meals.
How to
Give Aluminium Hydroxide: Mixing
Binders with Food
Phosphorus binders must be given with food so they can bind with the
phosphorus in it. Aluminium hydroxide binders are
usually odourless and tasteless if you choose carefully, but since they
are a natural (mined) product, they can sometimes add a bit of a gritty
texture to food or make it taste a little drier.
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
Conferenceare 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.
Giv
ing 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 above).
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.
Giv
ing 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.
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
As
Drugs mentions, 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). The most commonly used citrate-containing products in
CKD cats are potassium
citrate (perhaps to treat
metabolic acidosis), and many therapeutic kidney diets.
If you are using potassium citrate, give this at least two hours apart from
aluminium-based
binders.
It is trickier to juggle aluminium hydroxide and
therapeutic kidney diets
because binders of course 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.
"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
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
Zeniquin).
Plumb's also recommends separating aluminium hydroxide
from
corticosteroids.
Aluminium hydroxide should ideally be given separately from
iron,
because the aluminium hydroxide may reduce the absorption of the iron.
Plumb's Veterinary Drug Handbook also advises
giving aluminium hydroxide two hours apart fromfamotidine
(Pepcid AC), which is used to treat
excess stomach acid, 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.
Dr Larry Nagode
of Ohio State University
has stated that aluminium hydroxide should
be separated from
ACE inhibitors
such as benazepril (Fortekor) because it may interfere with the absorption
of the treatment, which would make it less effective.
Medline Plus mentions that
vitamin C may interact adversely with products containing aluminium,
such as phosphorus binders. Cats do not need Vitamin C
supplements anyway, they can manufacture all the Vitamin C they need
themselves.
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.
(2011) Mudge DW, Johnson DW, Hawlet CM, Campbell SB,
Isbel NM, van Eps CL & Petrie JJB Nephrology12
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 Nephrology12 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 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 LDJournal of Veterinary
Internal Medicine22(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 & Surgery11(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. 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,Dr D Chew 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
above). 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
Drugs 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 table
above), and most cases in dogs have occurred in dogs taking
over 200 mg/kg. In
Updates in feline chronic kidney disease
(2008) Dr CL Langston 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 lanthanumcarbonate (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 of the matter 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.
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 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 Failure33(2) pp217–224 found that lanthanum carbonate-based binders appear
to be as effective as aluminium hydroxide-based binders.
The two most commonly used forms of lanthanum are Fosrenol and Renalzin.
Renalzin is designed for cats but sadly has been discontinued so is very
hard to find. Fosrenol is a human medication.
In October 2008 a binder containing lanthanum carbonate known as Renalzin
was released in Europe for the feline market. Sadly, in late
2014 the manufacturer, Bayer, announced that Renalzin was to be
discontinued and it is now (2016) extremely hard to find and will probably
disappear completely by the end of the year.
Renalzin contains Vitamin E and kaolin as well as lanthanum carbonate. The
vitamin E is intended to act as an
antioxidant,
and the kaolin as a "toxin binder", by which I think they mean an
oral
adsorbent. Kaolin (which is often used to treat diarrhoea) can be
constipating, so it seems an unusual choice of ingredient, but I suspect
Bayer were jumping on the
Ipakitine/Epakitin bandwagon here by wanting to add
an oral adsorbent.
Renalzin also contains the preservative Methyl
4-hydroxybenzoate (E218). According to the
UK
Food Guide, this additive is banned in Australia
and France. A
German site, the
Lebensmittel-Lexikon(Food
Lexicon), says that it has a high allergic potential and may cause asthma
attacks.
As stated above, Renalzin, the feline version of lanthanum carbonate, has
been discontinued.
Renalan, another lanthanum-based
phosphorus binder, was undergoing testing on cats and
was reported to be seeking regulatory approval
in 2008 but it seems to have disappeared.
Therefore your only choice once Renalzin is no longer available will be
Fosrenol. Fosrenol is the human version of
lanthanum carbonate which 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 tabletswhich are supposed to be chewed,
but in order to use them for cats, most people crush
the tablets.
Eurek Alert
has a press release regarding the approval process for Fosrenol in the
USA.
Lanthanum Carbonate Dosage Recommendations
Fosrenol dosing is 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.
Having said that, there are a number of recommended dosage
protocols, as follows:
states "doses of 35 mg/kg/day to 50 mg/kg/day are often needed
since commercial cat foods contain more phosphate proportionally than what
an average human consumes daily. A recent abstract in a small number of
CKD cats administered lanthanum carbonate in food at 95 mg/kg/day to
achieve very modest serum phosphate control (Pressler ACVIM 2013)."
The
International Renal Interest Society
The International Renal Interest Society
(2015) recommends a staged approach to phosphorus control, as shown in the
tables below. It recommends using binders if phosphorus levels are as shown
in the tables
despite dietary restriction of phosphorus.
USA
Stage of CKD
Creatinine Level (mg/dl)
Current
Phosphorus Level
Binder Dosage
IRIS Stage 2
Between
1.6 and 2.8
Above 4.6 mg/dl
14-28 mg per lb of cat per day
IRIS Stage 3
Between 2.9
and 5.0
Above 5.0 mg/dl
14-28 mg per lb of cat per day
IRIS Stage 4
Over 5.0
Above 6.0 mg/dl
14-28 mg per lb of cat per day
International
Stage of CKD
Creatinine Level (mmol/L)
Current
Phosphorus Level (mmol/L)
Binder Dosage
IRIS Stage 2
Between
140 and 249
Above 1.5
30-60 mg per kg of cat per day
IRIS Stage 3
Between 250
and 439
Above 1.6
30-60 mg per kg of cat per day
IRIS Stage 4
Over 440
Above 1.9
30-60
mg per kg of cat per day
As you
can see, the recommended amounts of binder are actually the same for
each 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. See
The
Importance of Phosphorus Control for more information on your
phosphorus goals.
Renalzin is supplied in pump form and one dose provides 1 ml, which
contains 200mg of lanthanum carbonate. Bayer recommends that two pumps (2ml) a day are used
for dry food, giving a total dose
of 400mg of lanthanum carbonate each day. For canned food, it recommends
three pumps a day (3ml), giving a total dose of 600mg of lanthanum
carbonate each day,
Compared with the
recommended human starting dose for
Fosrenol (which also
contains lanthanum carbonate) of 750-1500mg a day, this seems relatively high.
However, veterinary sources have stated that lanthanum carbonate can be
dosed in the same way as aluminium hydroxide, in which case 400mg is
within normal levels for a 10 lb cat, but 600mg seems quite high. You can see
a summary of the recommended lanthanum carbonate dosages
below.
It is not essential to give Renalzin only twice a day, the total
daily dose can be
calculated and spread over
all meals. Phosphorus levels should
be checked after 2-4 weeks and the dose adjusted as required. Like
Ipakitine/Epakitin,
Renalzin is supposed to be given for up to six months
only, but most CKD cats
have an ongoing requirement for phosphorus control.
Lanthanum Carbonate Dosage
Calculations and Adjustments
I expect your head is spinning now! I know quite a few people get confused
by all these recommended dosages, so here is a summary:
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
Dr Chew
35-50 mg
80-114 mg
119-170mg
158-225 mg
200-285 mg
ISFM**
30-90 mg
68-204 mg
102-306 mg
135-405mg
170-513 mg
Renalzin
400 mg per cat per day
400 mg
400 mg
400 mg
400 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
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.
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 on your
phosphorus goals.
Lanthanum Carbonate
:
Choosing a Dosage
The
ranges for how much to give are quite wide, so talk to your vet
about a suitable starting point for your cat.
Taking
all the experts' recommendations above, 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 µmol/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
Lanthanum Carbonate: Adjusting a 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.
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 reduces 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.
How to
Give Lanthanum Carbonate: Mixing
Binders with Food
Phosphorus binders must be given with food so they can bind with the
phosphorus in it.
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
Conferenceare 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.
Giv
ing Binders with Canned
Food
Fosrenol
tablets can simply be crushed
and added to the food in
appropriate amounts.
Renalzin can be
sprayed directly onto food. The
product on sale in Germany says that three pumps (3ml) a day should be mixed
with canned food. I have no idea what you are supposed to do
if you are feeding both dry and canned, presumably average it out.
Renalzin is supposed to be odourless and tasteless and many members of
Tanya's CKD Support Group find their cats accept it happily in their food
(apparently it makes canned food quite creamy), but one user in Germany
has reported that it tasted slightly bitter and mouldy to her.
Giv
ing Binders with Dry Food
Fosrenol
tablets can simply be crushed
and added to the food in
appropriate amounts. Try putting the food in a freezer bag together with the crushed binder and leave them to mingle
overnight.
Renalzin can be
sprayed directly onto food. The
product on sale in Germany says that two pumps (2ml) a day should be mixed
with dry food. I have no idea what you are supposed to do
if you are feeding both dry and canned, presumably average it out.
Renalzin is supposed to be odourless and tasteless and many members of
Tanya's CKD Support Group find their cats accept it happily in their food
(which it makes quite creamy), but one user in Germany
has reported that it tasted slightly bitter and mouldy to her.
Lanthanum Carbonate-based BindersSide 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. The manufacturer confirmed to one person's vet that
these were possible side effects.
In September 2011 an
Important Drug Warning
was issued warning of a risk of faecal impaction when using
Fosrenol. The warning advises caution for patients who are constipated,
diabetic or using a calcium channel blocker (such as
amlodipine, used to treat high blood pressure in CKD cats).
"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. Renalzin is not absorbed into the digestive tract like aluminium hydroxide-based binders, and therefore should have fewer possible interactions with
other treatments. Nevertheless, Bayer recommends that it
should be separated from any other medications by 1-3 hours, particularly
benazepril. Please see
below for
more on possible interactions.
It is probably wise to keep lanthanum
carbonate away
from
antibiotics
generally, particularly those in the same family as Baytril (this includes
Zeniquin).
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, all of which
have additional ingredients and cost a lot more. See
below for stockists.
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.
A kg is 2.2 lbs, so for a
10lb (4.5kg) cat, you would give 135-200mg of binder
three times a day or 202mg of binder twice a day, resulting in a daily total of 405mg of binder.
As you
can see, the recommended amounts of binder are actually the same for
each 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. See
The
Importance of Phosphorus Control for more information on your
phosphorus goals.
Calcium Carbonate
You can buy calcium carbonate-based binders over the
counter - Tums is a widely available product of this type.
The risk of hypercalcaemia is lower with calcium
carbonate-based binders than with calcium
acetate-based, though it still exists. These 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 now make calcium carbonate-based products for
cats, most of which have additional ingredients, as follows:
These are the
recommended dosages for over the counter calcium carbonate products. If
you are using one of the branded products discussed below, follow the
manufacturer's recommendations after discussion with your vet.
A kg is 2.2 lbs, so for a
10lb (4.5kg) cat, you would give 135-200mg of binder
three times a day or 202mg of binder twice a day, resulting in a daily total of 405mg of binder.
As you
can see, the recommended amounts of binder are actually the same for
each 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. See
The
Importance of Phosphorus Control for more information on your
phosphorus goals.
Ipakitine/Epakitin
Ipakitine
(known as
Epakitinin the USA and Canada) is a combination of a calcium
carbonate-based phosphorus binder and chitosan. In
Renal disease in cats
(2013) Crieff 2 Day Small Animal CPD Meeting pp125-144 Prof D Gunn-Moore says that chitosan is combined with
calcium carbonate "to reduce
phosphate absorption from the intestines." Some people believe chitosan
may also act as
an
oral
adsorbent and help bind with uraemic toxins,
thus improving wellbeing. There is more information about Ipakitine, including its adsorbent
properties, on the
Treatments
page.
In the marketing literature, emphasis seems to be placed on
Ipakitine's role as a phosphorus binder, but
many 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 on uraemic toxins.
It is 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 stated it should be OK to give it for
longer for six months under veterinary supervision.
I have not been able to find out exactly how much
calcium carbonate is in Ipakitine in the UK or Epakitin in the USA.
Drugs states that 1g of the Canadian
version of Epakitin contains 100mg of calcium carbonate and 80mg of
chitosan, and I presume the US and European versions are similar. The
recommended dose is 1g of Epakitin per 5kg (11 lb) of cat given twice a
day with meals, which equates to 200mg of calcium carbonate per day for an
11 lb (5kg) cat. This is within typical veterinary guidelines for calcium
carbonate dosages, see below.
According to the
manufacturer, Ipakitine contains a high
(70-90) percentage of lactose,
so I would not use it if your cat is lactose intolerant.
Renal, made by Candioli Pharma in Italy,
is a similar product to Ipakitine. It is commonly offered to people in
Italy, and also those in Canada, where it is marketed by Aventix Animal
Health. Like Ipakitine, it contains calcium carbonate and chitosan, but
also contains potassium citrate. Since not every CKD cat needs additional
potassium, I think I would give this product a miss.
Renaltan
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. The manufacturer's website
does not specify the precise amounts of any of the ingredients, so I do
not know how much calcium carbonate it contains, or how much of anything
else, come to that.
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
prescription 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), prescription foods do have other
attributes (see
Which Foods to Feed for information on when and why to use
prescription food).
I have heard from a few German users who seem to like Renaltan. It is
available from the manufacturer's own website (first link above), from
Tiernaturprodukte or from
Amazon Germany. Since I don't know the
precise composition of this product, I would not use it.
Pronefra
Pronefra,
made by Virbac, is a new phosphorus binder 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%) to bind with uraemic
toxins
astragalus (9.5%) for renal
fibrosis
fish protein hydrolysate (1.9%) for hypertension
Binders containing magnesium are not really 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.
Pet Education
states "Do not use magnesium containing products in
animals with kidney failure."
Chitosan is also contained in Ipakitine, see
above.
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 Protein Powder,
though I am not sure whether Pronefra contains enough to make a
difference.
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.
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 Journal67(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 2016),
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.
Calcium-based Binders
Side Effects
Hypercalcaemia in cats (2001), a paper by
Dr Chew presented 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. You should not use a calcium-based binder
if your cat is taking
calcitriol.
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, Dr D Chew 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 the situation with your vet.
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 binders for some reason, though there
is little evidence for their use in cats. 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,
Dr D Chew 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."
Renagel (sevelamer hydrochloride) is a relatively new
phosphorus binder approved for use in humans, with not much history
of use in cats.
Doctor's
Guide has information on the
approval of Renagel for use in the USA.
In
Renal disease in cats
(2013) Crieff 2 Day Small Animal CPD Meeting pp125-144 Prof D
Gunn-Moore 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 kg is 2.2 lbs, so for a
10lb (4.5kg) cat, you would give 150-240mg of binder
three times a day or 225-360mg of binder twice a day, resulting in a daily total of
450-720mg of binder.
Sevelamer-based BindersSide 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.
Iron-Based Binders:
Lenziaren and Velphoro
Lenziaren
Lenziaren (also known as SBR759) is a new 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 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 Therapeutics38(3)
pp278–289 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 Therapeutics38(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 new 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.
It can be difficult deciding which binder to use. Traditionally people
used aluminium hydroxide, but this is now harder to find in the USA, and
some people are uncomfortable about the possibility of aluminium toxicity.
Many members of Tanya's CKD Support Group
switched to lanthanum carbonate for these reasons, but following the
discontinuation of Renalzin, it is not easy to find this cheaply.
Here is a summary of the pros and cons of each binder type, followed by my
own experiences and thoughts. Ultimately, if your cat needs a phosphorus
binder, I would say the most important thing is that s/he receives one.
Aluminium Hydroxide
Pros and Cons
Pros
They
are very effective, are available over the counter (at
least in theory), are cheap, and have no taste or smell so most cats are
prepared to eat them in their food.
Cons
They may cause constipation, may need to be tracked
down in the USA, and there is a risk, albeit a relatively small one, of
aluminium toxicity.
Lanthanum Carbonate Pros and
Cons
Pros
They are very effective (as effective as
aluminium hydroxide), have little taste or smell so most cats are prepared
to eat them in their food, and (if you can obtain Renalzin) are
relatively cheap.
Cons
Renalzin has been discontinued and alternative products
are very expensive. Lanthanum-based products may cause constipation, and serious problems
may be seen if given to
patients who are constipated, diabetic or using a calcium channel blocker
(such as
amlodipine for high blood pressure).
Calcium-based Binders
Pros and Cons
Pros
They are cheap, available over the counter and there
are a variety of commercial preparations which are formulated to be
palatable and to provide possible additional benefits (though these are
not as cheap).
Cons
They do not bind phosphorus as effectively as aluminium
hydroxide or lanthanum, and may cause elevated calcium levels. Some may
also interact with stomach acid blockers such as famotidine (Pepcid AC).
Sevelamer-based Binders
Pros and Cons
Pros
They may be helpful for cats who cannot use the other
types of binder for some reason.
Cons
There is
little history of use in cats but these binders appear to be less
effective than lanthanum. They may cause problems with blood clotting,
and
may cause elevated calcium levels. Like
many other binders, they can cause constipation.
Iron
-based Binders
Pros and Cons
Pros
Appear to be effective, based on limited studies and
feedback I have received. One study found this type of binder seemed to improve appetite,
though that study used healthy cats.
Cons
Not yet
available in western countries. May be necessary to monitor iron levels as
well as phosphorus levels. Phosphorus levels actually increased in the
healthy cats who received this type of binder.
My Experiences
I have used aluminium hydroxide and Ipakitine (which is
calcium carbonate-based) for my cats. I have not used lanthanum, sevelamer or iron-based
binders.
Both aluminium hydroxide and Ipakitine worked just fine
for my cats. As far as the Ipakitine went, Ollie did not have particularly
high phosphorus levels to start with, whereas Thomas, who received
aluminium hydroxide, did.
My own vet in the UK has seen falls in creatinine and
BUN (urea) in some cats when using
Ipakitine and no other treatments.
In principle I would certainly be happy to try lanthanum carbonate,
but since it is now horrendously expensive following the withdrawal of
Renalzin from the market, I doubt I would bother.
Personally, I would probably reach first for aluminium hydroxide,
not least because it is effective, easy to obtain in the UK and not too expensive.
However, if I had a cat in early stage CKD with moderately elevated blood
phosphorus levels (between 6 and 7 mg/dl (USA) or 1.9 and 2.25
mmol/L (international)
but normal blood calcium levels, I would consider using
a commercial calcium carbonate preparation such as Ipakitine because my vet is
very familiar with it, it is easy to source, not too
expensive, and it may have additional benefits. I would ask my vet to
monitor my cat's blood calcium levels.
For a cat with higher phosphorus levels (over 7 mg/dl (USA) or 2.25 mmol/L
(international),
or a cat with moderately elevated phosphorus levels but elevated calcium
levels, I would definitely opt to use an aluminium hydroxide binder. Even for cats
with lower phosphorus levels, if the cat's phosphorus multiplied by
total calcium is higher than 70in US
values or 5 in international values, the cat is at risk of tissue
calcification (see
secondary
hyperparathyroidism). In such a case, again I would opt to
use an aluminium hydroxide binder in order to get the
phosphorus levels under control as quickly as possible.
Don't forget, if the binder you choose doesn't seem to
be helping, or doesn't seem to suit your cat, you can always try another,
either instead of or in addition to the binder you are using.
The most important thing, if your cat needs a binder,
is to use one.
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. This often is the
case when people do not wish to give higher doses of aluminium
hydroxide-based binders, so choose to add lanthanum carbonate.
In
such cases, 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.
It is fine in this situation to mix the binders when
you give them. So if, for example, you feed your cat three times a day,
you can calculate how much aluminium hydroxide you need to give in total
for the day and how much lanthanum carbonate you need to give in total for
the day, and then give a third of each to your cat with each meal.
Phosphorus binders must be given with food so they can bind with the
phosphorus in it. Aluminium hydroxide binders are
usually odourless and tasteless if you choose carefully, but since
they are a natural (mined) product, they can sometimes add a bit of a
gritty texture to food or make it taste a little drier. Lanthanum
carbonate binders are also supposed to be odourless and tasteless but some
people think Renalzin tastes bitter. Calcium-based binders can taste a bit
chalky.
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
Conferenceare 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.
Giv
ing 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 above).
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.
Giv
ing 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.
In theory, a cat receiving binders may
develop the opposite of what you are trying to treat, i.e. low phosphorus
levels (hypophosphataemia).
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, 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."
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 prescription 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.
If you are in the USA, you could also consider using
Conseal AlH as discussed
below.
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
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 tubs
from a number of online pharmacies, but the only one which definitely
still sells it these days is Thriving Pets, though most local
compounding pharmacies should be able to order it for you.
It may take a local pharmacy a few days to obtain it
for you; 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.
If you need aluminium hydroxide quickly, it is probably
Sells 500g (1.1 lbs) of aluminium hydroxide dry gel for US$79.95
plus shipping. They also sell 1 oz at a time, as well as capsule or liquid
(oral) formulations (these require a prescription, which the gel
formulation does not) . If you enter the word "tanya" (without the
") in the promotional code box, you will receive a 10% discount on orders
over US$55. Shipping is free for orders over US$55 after the discount.
Phos-Bind
Phos-Bind is a newer brand of loose
aluminium hydroxide binder made by Rx Vitamins. It is essentially a tub of
loose aluminium hydroxide powder in a 200g size (just over 7 ounces).
Has another seller selling 200g (a bit less than 8 oz) for US$38 including
free shipping
ConSeal AlH
Conseal AlH are aluminium
hydroxide 200 mg chews made by Bock Pharma. They come in a box of 28
individually wrapped chews. The recommended dose is 1-2 chews per 10 lbs
of cat given with meals. If you need to give less, the chews are semi-soft
so can be broken or cut into pieces. In this form they can be mixed with
food, but one member of
Tanya's CKD Support Group
found the chews very helpful for her cat who missed getting
treats, and gave them before her cat's meals. They could also be useful
for multi-cat households where you can give your CKD cat a Conseal treat
whilst giving your other cats ordinary treats.
Conseal AlH apparently has to be ordered through your vet, and a pack
costs about $20-$25.
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.
sells thirty 1000mg Fosrenol tablets for US$364.77 or 50 for US$589.01.
You have to buy them from your local Costco pharmacy with a prescription
but you do not have to be a member of Costco to use their pharmacies.
Sell ninety Fosrenol 500mg or 1000mg tablets for
US$999.95. A prescription is required. If you enter the word "tanya" (without the ") in the
promotional code box, you will receive a 10% discount on orders over
US$100. Shipping is free for orders over US$100 after the discount.
In the UK, sells Renalzin for £8.40 for 50ml or £22.34 for 150ml. For
parcels weighing less than 2kg (4.4lbs), shipping is a flat rate £10
and delivery usually takes 2-3 weeks. This pharmacy has shipped
Renalzin to US members of my support group with no problems. Renalzin
is being discontinued by the manufacturer, so supplies will run out
some time during 2015.
Sells Epakitin for US$22.82
(50g), US$54.99 (150g)
or US$76.16 (300g).
Sources - UK
Aluminium Hydroxide UK
Alucapsare an odourless
and flavourless phosphorus binder made by 3M,
and are your best bet in the UK. They are available as follows:
Members ofTanya's CKD Support Group
in the UK have successfully obtained Alucaps from Boots, Lloyds and
Superdrug during 2015, though some people have found it harder in 2016. In August 2014
Alucaps cost around £12 for
120 capsules of 475mg aluminium hydroxide from many
branches of Boots and other chemists, but since then many people
have been asked to pay as much as £16-20.
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. When I asked for Alucaps in Boots, the
pharmacist had never heard of them, but - unbeknownst
to her - she
did actually have some in stock; so you
may need to be persistent or ask for them to be
ordered for you.If they need to be ordered,
theyshould only take
a couple of days to arrive, and it is fine to wait that
long.
Sells Alucaps online for
17p per capsule (so 120 capsules cost
£20.40) plus
£3.95 delivery,
though for some reason they require a prescription if bought this way.
In the UK sells Renalzin for
£8.40 for 50ml or £22.34 for 150ml. Delivery costs
£2.99 for orders under
£29, and is free otherwise. Renalzin is being discontinued by the
manufacturer, so supplies will run out some time during 2015.
Sells an aluminium hydroxide
based binder called
Basaljel made by Axcan Pharma Inc.
It comes in gelcaps, each containing 500 mg of aluminium hydroxide, and
they cost CAN$26.95 for 100. Basaljel is also available over the counter
in many Canadian pharmacies.
Sells 500g of aluminium hydroxide, you
can
contact
them to
check the current price, but for reference, in March 2016 one member ofTanya's CKD Support Group paid CAN$90
including
shipping to Newfoundland.
In the UK sells Renalzin for
£8.40 for 50ml or £22.34 for 150ml. For parcels weighing less than 2kg
(4.4lbs), shipping is a flat rate £10 and delivery usually takes 2-3
weeks.
This
pharmacy has shipped Renalzin to US members of my support group with no problems.
Renalzin is being discontinued by the manufacturer, so supplies will run
out some time during 2015.
Sources - Australia and New Zealand
Alu-Tabs, made by iNova
Pharmaceuticals, are probably your best bet. They come in 600mg tablets
rather than a powder, but I imagine you could 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.
TREATING YOUR CAT WITHOUT VETERINARY ADVICE CAN BE
EXTREMELY DANGEROUS.
I have
tried very hard to ensure that the information provided in this website is
accurate, but I am NOT a vet, just an ordinary person who has lived
through CKD with three cats. This website is for educational purposes
only, and is not intended to be used to diagnose or treat any cat. Before
trying any of the treatments described herein, you MUST consult a
qualified veterinarian and obtain professional advice on the correct
regimen for your cat and his or her particular requirements; and you
should only use any treatments described here with the full knowledge and
approval of your vet. No responsibility can be accepted.
If your cat
appears to be in pain or distress, do not waste time on the internet,
contact your vet immediately.
This site was
created using Microsoft software, and therefore it is best viewed in
Internet Explorer. I know it doesn't always display too well in other
browsers, but I'm not an IT expert so I'm afraid I don't know how to
change that. I would love it to display perfectly everywhere, but my focus
is on making the information available. When I get time, I'll try to
improve how it displays in other browsers.
You may print
out one copy of each section of this site for your own information and/or
one copy to give to your vet, but this site may not otherwise be
reproduced or reprinted, on the internet or elsewhere, without the
permission of the site owner, who can be contacted via the
Contact Me
page.
This site is a labour of love, from which I do not make
a penny. Please do not steal from me by taking credit for my work.
If you wish to
link to this site, please feel free to do so. Please make it clear that
this is a link and not your own work. I would appreciate being informed of
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