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Contra-indications, warnings, etc
Do not use in animals with known hypersensitivity to the active substance.
Use is contra-indicated in animals suffering from cardiac, hepatic or renal disease, where there is the possibility of gastro-intestinal ulceration or bleeding or where there is evidence of a blood dyscrasia.
Do not use in animals suffering from thyroid disease.
Do not use in animals with severe hypertonia.
Do not use in animals with lesions in the intestinal mucosa, caused by parasitic infestations.
Adverse reactions
In common with other NSAIDs that inhibit prostaglandin synthesis, there may be gastric and/or renal intolerance. This is usually associated with overdosage and such events are rare. Recovery is usual on cessation of treatment and following the initiation of supportive symptomatic therapy.
Blood dyscrasia may occur.
Ponies are very sensitive to gastric ulceration with this product, even at therapeutic doses (diarrhoea, ulceration in the mouth and hypoproteinaemia may also be seen).
If adverse reactions occur, treatment should be discontinued and the advice of a veterinarian should be sought.
If you notice any serious effects or other effects not mentioned in this leaflet, please inform your veterinary surgeon.
Special warnings for each target species
The clinical effects of phenylbutazone can be evident for at least three days following cessation of therapy. This should be borne in mind when examining horses for soundness.
FEI regards phenylbutazone as prohibited substance, it should be administered in accordance with FEI recommendations.
Special precautions for use in animals:
Do not exceed the stated dose of 8.8 mg/kg/day as the therapeutic index of phenylbutazone is low.
Use in any animal less than 6 weeks of age or in aged animals may involve additional risk. If such use cannot be avoided animals may require careful clinical management.
Avoid use in any dehydrated, hypovolaemic or hypotensive animal as there is a potential risk of increased renal toxicity. Keep water readily available during the treatment period to avoid dehydration.
NSAID’s can cause inhibition of phagocytosis and hence in the treatment of inflammatory conditions associated with bacterial infections, appropriate concurrent antimicrobial therapy should be instigated.
Special precautions to be taken by the person administering the veterinary medicinal product to animals:
This product may cause hypersensitivity (allergic) reactions in those sensitized to phenylbutazone, either via skin contact or accidental inhalation.
People with known hypersensitivity to phenylbutazone, or any of the excipients, should avoid contact with this product.
If you develop symptoms following exposure, such as skin rash, you should seek medical advice and show the doctor this warning. Swelling of the face, lips or eyes, or difficulty breathing, are more serious symptoms and require urgent medical attention.
This product can be irritating to the skin and the eyes. Avoid contact with the eyes. In case of accidental eye contact, irrigate eyes with plenty of clean water. If irritation persists seek medical advice. Wash any exposed skin and hands after use.
Care should be taken to avoid ingesting the powder. In the event of accidental ingestion, seek medical advice and show the product packaging to the physician.
Use during pregnancy and lactation:
Care should be exercised if administered to pregnant mares. Although no adverse effects of phenylbutazone on the foetus or maintenance of pregnancy have been reported during field use, no definitive safety studies have been carried out in the mare. Foetotoxic effects of phenylbutazone have been recorded in experimental animal species at high dose levels.
Use phenylbutazone in pregnant and lactating mares only according to a benefit/risk assessment by the responsible veterinarian Avoid use around time of parturition.
Interaction with other medicinal products and other forms of interaction:
Do not administer other NSAID’s concurrently or within 24 hours of each other.
Concurrent administration of potential nephrotoxic drugs should be avoided.
Phenylbutazone induces hepatic microsomal enzyme activity.
There is a potential risk of increased renal toxicity after concurrent administration of aminoglycosides.
Concomitant use of glucocorticoids, other NSAIDs or anticoagulants increase adverse effects of phenylbutazone.
Therapeutic efficacy of diuretics may be reduced when used in combination with phenylbutazone-containing products
Phenylbutazone is extensively bound to plasma proteins. It may displace other drugs that are highly protein bound, e.g. some sulphonomides, warfarin or it may itself be displaced to produce an increase in non-bound pharmacologically active concentrations, which can lead to toxic effects.
Concurrent therapy with other therapeutic agents should be undertaken with caution due to the risk of metabolic interactions. Phenylbutazone may interfere with the metabolism of other drugs, e.g. warfarin, barbiturates with resultant toxicity.
There is evidence to indicate that the pharmacokinetics of penicillin and gentamicin products may be affected by concurrent administration of products containing phenylbutazone, with a possible reduction of therapeutic efficacy, since tissue penetration may be reduced. The distribution in other drugs given concurrently may also be affected.
Overdose (symptoms, emergency procedures, antidotes)
Overdosing may result in gastric and large intestinal ulceration and general enteropathy. Renal papillary damage may also occur with impaired renal function. Subcutaneous oedema, especially under the jaw, may become evident due to plasma protein loss.
In case of overdose CNS effects (excitement, seizures), hematuria and acidosis were observed. There is no specific antidote. If signs of possible overdosage occur, treat the animal symptomatically.
Do not mix this product with any other veterinary medicinal product.
Withdrawal period
Not for use in horses intended for human consumption. Treated horses may never be slaughtered for human consumption. The horse must have been declared as not intended for human consumption under national horse passport legislation.