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Description:
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ALLOPURINOL
- Used as a uric acid reducer in dogs, cats and birds and as an
alternative treatment Leishmaniasis and Tryansomiasis in dogs
- Use with caution (dosage adjustment may be required) in patients with
renal or hepatic dysfunction.
- Diet may need to be adjusted.
- GI effects are most likely adverse effects, but hepatic and renal
effects can occur
- Many potential drug interactions.
Pharmacology
Allopurinol and its metabolite, oxypurinol, inhibit the enzyme xanthine
oxidase. Xanthine oxidase is responsible for the conversion of oxypurines
to uric acid. Hepatic microsomal enzymes may also be inhibited by
alloputinol.
It does not increase the renal excretion of uric acid nor does it possess
any anti-
inflammatory or analgesic activity.
Allopurinol, by inhibiting xanthine oxidase, can also inhibit
the formation of superoxide
anion radicals, thereby providing protection against hemorrhagic shock and
myocardial
ischemia in laboratory conditions. The clinical use of the drug for these
indications re-
quires further study.
Uses/Indications
The Principal veterinary uses for allopurinol are for the
prophylactic
treatment of recurrent uric acid uroliths and hyperuricosuric calcium
oxalate uroliths in
small animals. It has also been used in an attempt to treat gout in pet
birds.
allopurinol has also been recommended as an alternative
treatment for canine Leishma-
niasis. Although it appears to have clinical efficacy, it does not
apparently clear the para-
site in most dogs at usual dosages. Allopurinol may also be useful for
American try-
panosomiasis.
Contradiations/Precations
Allopurinol is contraindicated in patients who are hy-
persensitive to it or have previously developed a severe reaction to it. It
should be used
cautiously and with intensified monitoring in patients with impaired hepatic
or renal func-
tion. When used in patients with renal insufficiency, dosage reductions and
increased
monitoring are usually warranted.
Dosage
Dogs:
For urate uroliths:
a) 7-10 mg/kg PO
tid for both dissolution and prevention. Goal is to reduce urine
urate:creatinine ratio by 505.
b) for dissolution:
15 mg/kg PO q12h; only in conjunction with low purine foods.
for precention:10-20 mg/kg/day; because prolonged high doses of allopurinol
may result in zanthine uroliths, it may be preferable to minimize recurrence
with dietary therapy, with the option of treating infrequent episodes of
urate
urolith formation with dissolution protocols.
c) Alkalinize
urine to a pH of 6.5-7 ( see sodium bicarbonate monograph), give
low purine diest and eliminate any UTI, Allopurinol at 10 mg/kg tid for the
first
month, then 10 mg/kg once daily thereafter. Reduce dose in patients with
renal
failure.
For Leishmaniasis:
a) 15 mg/kg PO
twice daily for months
b) If possible use
with meglumine antimonate, if not use allopurinol alone at 10
mg/kg PO twice daily. If animal has renal isufficiency use at 5 mg/kg PO
twice
daily.
Cats:
For Urate Uroliths:
a) 9 mg/kg PO per day.
Birds:
For Gout:
a) In budgies
and coakatiels: Crush one 100 mg tablet into 10 ml of water. Add 20
drops of this solution to one ounce of drinking water.
b) For parakeets:
Cruch 100 mg tablet into 10ml of water. Add 20 drops of
this solution to one ounce of drinking water or give 1 drop 4 times daily.
Reptiles:
For elevated uric acid levels in renal disease in
lizards:
a) 20 mg/kg PO once
daily.
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