페니토인

투여 경로

금기

• Cats (due to severe toxicity)
• Hepatic dysfunction
• Bradycardia
• High-grade AV block

이상반응

• Hepatotoxicity (especially in dogs)
• Ataxia
• Sedation
• Gingival hyperplasia
• Peripheral neuropathy
• Hypotension and arrhythmias (with rapid IV administration)

약물 상호작용

• Phenobarbital · Unpredictable effects on serum concentrations of both drugs due to CYP450 induction · moderate
• Chloramphenicol · Inhibits hepatic metabolism of phenytoin, leading to increased levels and toxicity · major
• Cimetidine · Inhibits metabolism of phenytoin, increasing risk of toxicity · moderate
• Corticosteroids · Phenytoin induces hepatic enzymes, increasing the clearance and reducing the efficacy of corticosteroids · moderate

모니터링

• Serum drug concentrations (therapeutic range typically 10-20 mcg/mL, though rarely monitored now due to infrequent use)
• Liver enzymes (ALT, AST, ALP) and bilirubin
• ECG and blood pressure during IV administration

과용량

Clinical signs of overdose include severe ataxia, tremors, lethargy, vomiting, and paradoxical seizures. Rapid IV overdose leads to hypotension and cardiac arrest. **Treatment:** Consists of supportive care, IV fluid therapy, and cardiovascular monitoring. There is no specific antidote.