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NERVOUS SYSTEM › ANTIEPILEPTICS › ANTIEPILEPTICS › Hydantoin derivatives
mephenytoin, combinations
N03AB54
Forms & Strengths
- oral capsule 100mg
- oral tablet 100mg
Adult Dosing
- initial dose 100mg tid, increase by 50-100mg every 7 days
- maintenance dose 300-400mg/day in 3 divided doses
- maximum dose 600mg/day
Pediatric Dosing
- children 5-12 years: initial dose 50mg tid, increase by 25-50mg every 7 days
- adolescents >12 years: initial dose 100mg tid, increase by 50-100mg every 7 days
Indications
- treatment of partial seizures
- treatment of generalized tonic-clonic seizures
- treatment of mixed seizure disorders
Mechanism of Action
- blocks sodium channels, reducing neuronal excitability
- inhibits repetitive neuronal discharges, stabilizing neuronal membranes
Contraindications
- hypersensitivity to mephenytoin or other hydantoins
- porphyria
- pregnancy, especially during first trimester
Adverse Reactions
- dizziness, ataxia, and nystagmus
- rash, gingival hyperplasia, and hirsutism
- neutropenia, thrombocytopenia, and megaloblastic anemia
Drug Interactions
- phenytoin, valproic acid, and carbamazepine may increase mephenytoin levels
- barbiturates, primidone, and phenobarbital may decrease mephenytoin levels
- coumarin anticoagulants may have reduced efficacy with mephenytoin
Curated Content: Needs Vetting Before Put to Clinical Use