Phenytoin
Also known as: Epanutin, pro-Epanutin, Dilantin
Administer exactly as directed by your veterinarian. Do not stop this medication abruptly, as it may trigger severe seizures. Contact your veterinarian immediately if your pet develops jaundice (yellowing of the gums or eyes), severe lethargy, vomiting, or loss of coordination. > **CRITICAL:** Never give this medication to cats.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
How it is given
Possible side effects
- Hepatotoxicity (especially in dogs)
- Ataxia
- Sedation
- Gingival hyperplasia
- Peripheral neuropathy
- Hypotension and arrhythmias (with rapid IV administration)
Cautions & contraindications
- Cats (due to severe toxicity)
- Hepatic dysfunction
- Bradycardia
- High-grade AV block
- > **Warning:** Highly toxic in cats. > **Warning:** Rapid IV administration can cause severe hypotension, bradycardia, and cardiovascular collapse. Always administer IV slowly and monitor ECG.
Drug interactions
- Phenobarbital: Unpredictable effects on serum concentrations of both drugs due to CYP450 induction
- Chloramphenicol: Inhibits hepatic metabolism of phenytoin, leading to increased levels and toxicity
- Cimetidine: Inhibits metabolism of phenytoin, increasing risk of toxicity
- Corticosteroids: Phenytoin induces hepatic enzymes, increasing the clearance and reducing the efficacy of corticosteroids
Frequently asked questions
What is Phenytoin used for in pets?
Administer exactly as directed by your veterinarian. Do not stop this medication abruptly, as it may trigger severe seizures. Contact your veterinarian immediately if your pet develops jaundice (yellowing of the gums or eyes), severe lethargy, vomiting, or loss of coordination. > **CRITICAL:** Never give this medication to cats.
Is Phenytoin safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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