페니토인 나트륨
Phenytoin Sodium
Diphenylhydantoin
다른 이름: Dilantin · Phenytek · Diphenylhydantoin · DPH · Fenitoina · Phenantoinum · Phenytoinum
VetSheet 수의사 팀 검수업데이트 2026년 4월 5일근거 기반 수의학 참고자료
용량은 수의사 전문가를 위한 임상 참고자료입니다. 반드시 최신 약물 정보 및 개별 환자에 따라 확인하시기 바랍니다.
동물 종별 용량
🌎 NA — North America🌍 EU — Europe
개
| 적응증 | 용량 | 경로 | 빈도 | 기간 | 지역 |
|---|---|---|---|---|---|
| Treatment of seizures | 15-40 mg/kg | PO | three times daily | — | 🌎 NA |
| Treatment of seizures | 20-35 mg/kg | PO | three times daily | — | 🌎 NA |
| Treatment of seizures | 8.8-17.6 mg/kg in divided doses | PO | divided doses | — | 🌎 NA |
| Treatment of ventricular arrhythmias | Up to 10 mg/kg in increments of 2-4 mg/kg OR 20-35 mg/kg | IV or PO | three times daily (for PO) | — | 🌎 NA |
| Treatment of ventricular arrhythmias | 10 mg/kg slowly IV; 30-50 mg/kg PO | IV, PO | q8h (for PO) | — | 🌎 NA |
| Treatment (or prophylaxis) of digitalis intoxication | 50 mg/kg | PO | q8h | — | 🌎 NA |
| Treatment of hypoglycemia secondary to tumor | 6 mg/kg | PO | two to three times daily | — | 🌎 NA |
- Treatment of seizures: Gradually increase or decrease dose to maintain control. May take several days for seizure control. Note: Unlikely to attain necessary serum levels due to fast half-life.
- Treatment (or prophylaxis) of digitalis intoxication: Long-term use may cause increases in serum alkaline phosphatase and increased hepatic cell size.
고양이
| 적응증 | 용량 | 경로 | 빈도 | 기간 | 지역 |
|---|---|---|---|---|---|
| Treatment of ventricular arrhythmias | 2-3 mg/kg | PO | q24h | — | 🌎 NA |
| Treatment of seizures | 2-3 mg/kg daily; 20 mg/kg per week | PO | daily or weekly | — | 🌎 NA |
- Treatment of ventricular arrhythmias: Diligent monitoring is required due to accumulation risk.
- Treatment of seizures: Use is very controversial in this species.
말
| 적응증 | 용량 | 경로 | 빈도 | 기간 | 지역 |
|---|---|---|---|---|---|
| Seizures | 2.83-16.43 mg/kg | PO | q8h | — | 🌎 NA |
| Digoxin induced arrhythmias | 10-22 mg/kg | PO | q12h | — | 🌎 NA |
| Treatment of ventricular dysrhythmias | 20 mg/kg initially for the first 3-4 doses, followed by a maintenance dose of 10-15 mg/kg | PO | q12h | — | 🌎 NA |
- Seizures: To obtain serum levels from 5-10 micrograms/mL. Suggest monitoring serum levels to adjust dosage.
- Digoxin induced arrhythmias: Adverse effects are muscle fasciculations and sedation.
- Treatment of ventricular dysrhythmias: For persistent ventricular extra systoles or ventricular tachycardia where conventional treatment has failed. Suggest monitoring plasma concentrations.
용량은 수의사 전문가를 위한 임상 참고자료입니다. 반드시 최신 약물 정보 및 개별 환자에 따라 확인하시기 바랍니다.
개요
페니토인 나트륨(Phenytoin sodium)은 히단토인 유도체 항경련제이자 Class IB 항부정맥제입니다. 인의에서는 역사적으로 중요한 약물이지만, 반려동물에서는 약동학적 특성이 불리하여 수의학적 사용이 매우 제한적입니다.
- 개: 반감기가 매우 짧고 간 효소의 빠른 자가유도(autoinduction)가 일어나, 잦은 고용량 투여 없이는 치료 혈청 농도를 유지하기가 거의 불가능하므로 장기적인 간질 관리에 거의 사용되지 않습니다.
- 고양이: 반감기가 심각하게 연장(최대 108시간)되고 글루쿠론산 포합 경로가 결핍되어 있어 독성 축적에 매우 취약합니다.
- 임상적 활용: 현재는 주로 개와 말에서 디곡신 유발성 심실 부정맥을 치료하거나, 고양이의 특정 희귀 신경근 질환(예: 근파동증 및 신경근긴장증)에 제한적으로 사용됩니다.
임상 팁: 인슐린 분비를 억제하는 능력이 있어 인슐린종에 속발하는 저혈당증의 보조 치료제로 연구된 바 있으나, 임상적 이점은 대개 미미합니다.
작용 기전
Phenytoin exhibits both neurological and cardiac effects through the stabilization of excitable membranes:
- Neurological: Binds to and prolongs the inactive state of voltage-gated sodium channels (VGSCs) → promotes sodium efflux and limits sodium influx → stabilizes neuronal membranes and prevents the high-frequency repetitive firing necessary for seizure propagation from epileptogenic foci.
- Cardiac: Acts as a Class IB antiarrhythmic (similar to lidocaine) → slightly depresses phase 0 of the cardiac action potential and shortens phase 3 repolarization → decreases overall action potential duration. It is particularly effective against digitalis-induced arrhythmias.
- Endocrine: Inhibits the secretion of insulin and vasopressin (ADH).
안전성·주의사항
금기사항
- Hypersensitivity to phenytoin or other hydantoins
- Intravenous use is contraindicated in 2nd or 3rd degree heart block
- Sinoatrial block
- Adams-Stokes syndrome
- Sinus bradycardia
부작용
- Dogs: Anorexia, vomiting, ataxia, sedation, gingival hyperplasia, hepatotoxicity (elevated ALT, decreased albumin, hepatic lipidosis)
- Cats: Ataxia, sedation, anorexia, dermal atrophy syndrome, thrombocytopenia
- Horses: Excitement, recumbency (at high plasma concentrations)
주의
Hepatotoxicity Warning: Chronic therapy in dogs requires regular monitoring of liver function due to the risk of hepatocellular hypertrophy, necrosis, and hepatic lipidosis.
- Pregnancy: Potentially teratogenic (FDA Category D / Papich Class C). It readily crosses the placenta and is excreted in maternal milk. Use only when benefits clearly outweigh risks.
- Feline Sensitivity: Cats metabolize phenytoin extremely slowly. Use is highly controversial and requires diligent monitoring to prevent severe toxicity.
- IV Administration: Must be given slowly. Rapid IV injection can cause severe hypotension and cardiac arrhythmias.
약물 상호작용
Significantly increases the serum half-life of phenytoin (e.g., from 3 to 15 hours in dogs) by inhibiting its hepatic metabolism.
The toxicity of lithium may be enhanced.
Phenytoin may decrease the analgesic properties of meperidine but enhance its toxic effects.
Altered pharmacologic effects; potential for additive hepatotoxicity. Weigh risks vs. benefits before combining.
May increase the pharmacologic effects and toxicity of phenytoin.
May decrease the pharmacologic activity of phenytoin.
Phenytoin may decrease the pharmacologic activity of these agents via hepatic enzyme induction.
모니터링
- Level of seizure control or arrhythmia resolution
- Signs of toxicity (sedation, ataxia)
- Body weight (monitor for anorexia)
- Liver enzymes (ALT, ALP) and serum albumin (especially with chronic therapy)
- Serum drug levels (if signs of toxicity appear or lack of efficacy is noted)
약동학
반감기
흡수
Nearly completely absorbed in humans, but in dogs, oral bioavailability may only be about 40%.
분포
Well distributed throughout the body. About 78% bound to plasma proteins in dogs (vs. 95% in humans). Protein binding may be reduced in uremic patients. Readily crosses the placenta and small amounts are excreted into milk.
대사
Metabolized in the liver; much of the drug is conjugated to a glucuronide form. Phenytoin induces hepatic microsomal enzymes, enhancing the metabolism of itself (autoinduction) and other drugs.
배설
Excreted by the kidneys as metabolites.
과다투여
Clinical signs of overdosage are dose-dependent:
- Lower levels: Sedation, anorexia, and ataxia (wobbly gait).
- Higher levels: Coma, severe hypotension, and respiratory depression.
Treatment: Dogs rapidly clear the drug, so treatment depends on the severity of clinical signs. Severe intoxications require aggressive supportive care (IV fluids, cardiovascular and respiratory support).
제품
제형
- Extended-release capsules: 30 mg, 100 mg, 200 mg, 300 mg
- Oral suspension: 25 mg/mL
- Chewable tablets: 50 mg
- Injection: 50 mg/mL
동물용의약품
- None currently available
인용의약품
- Phenytoin Sodium Extended-Release Capsules: 30 mg, 100 mg, 200 mg & 300 mg (Dilantin Kapseals, Phenytek)
- Phenytoin Oral Suspension: 25 mg/mL (Dilantin-125)
- Phenytoin Tablets: 50 mg chewable (Dilantin Infa-Tabs)
- Phenytoin Sodium Injection: 50 mg/mL (46 mg/mL phenytoin base)
규제 현황
규제 데이터 없음: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
보관·안정성
Store capsules at room temperature (below 86°F) and protect from light and moisture. Store injection at room temperature and protect from freezing. If injection is frozen/refrigerated, a precipitate may form which should resolubilize when warmed. Do not use precipitated solutions. Injectable solutions will precipitate at a pH less than 11.5.
보호자 정보
- 엄격한 일정 준수: 처방된 대로 정확히 투약하십시오. 투약을 거르면 발작이 재발하거나 위험한 부정맥이 발생할 수 있습니다.
- 투약 방법: 음식과 함께 먹이면 흡수가 촉진되고 위장 장애를 줄일 수 있습니다.
- 부작용 관찰: 반려동물이 극도로 무기력해지거나, 식욕을 잃거나, 구토를 하거나, 비틀거리며 걷는(운동실조) 증상을 보이면 즉시 수의사에게 알리십시오.
- 치아 건강: 개의 경우 이 약물은 잇몸의 과도한 증식(잇몸 비대)을 유발할 수 있습니다. 정기적인 치과 검진과 철저한 구강 위생 관리가 중요합니다.
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안전 경고: 사람의 약을 반려동물과 절대 공유하지 마십시오. 동물이 이 약을 대사하는 방식은 사람과 매우 다르며, 잘못된 용량은 치명적일 수 있습니다.
VetSheet 의약품 참고자료는 수의사 전문가의 임상 의사결정 지원을 위한 것이며, 전문적 판단이나 제조사의 최신 약물 정보를 대체할 수 없습니다.