Pharmacology of Mephenytoin (Mesantoin) ; Mechanism of action, Pharmacokinetics, Uses, Effects

Mephenytoin, marketed under the brand name Mesantoin, is a hydantoin derivative used as an anticonvulsant for the treatment of epilepsy. It was introduced in the late 1940s, approximately 10 years after phenytoin. Pharmacology Mechanism of Action: Mephenytoin works by stabilizing neuronal membranes and reducing seizure activity. It inhibits sodium channels, which decreases the excitability of neurons and prevents the spread of seizure activity in the brain. Absorption: Mephenytoin is well absorbed when administered orally. Distribution: It is widely distributed throughout the body. Metabolism: Mephenytoin is metabolized in the liver by cytochrome P450 enzymes, including CYP2C19, CYP2C8, CYP2C9, CYP2B6, CYP1A2, and CYP2D6. The significant metabolite of mephenytoin is nirvanol (5-ethyl-5-phenylhydantoin), which is also active but more toxic. Elimination: The elimination half-life of mephenytoin is approximately 7 hours. It is excreted mainly in the urine as inactive metabolites. Indications Mephenytoin is used for the treatment of refractory partial epilepsy, particularly in patients who have not responded to less toxic anticonvulsants2. Side Effects Common side effects of mephenytoin include rash, nausea, vomiting, fatigue, ataxia, dizziness, nystagmus, somnolence, tremor, diplopia, depression, feeling nervous, and irritability. It can also cause potentially fatal blood dyscrasias in about 1% of patients #Mephenytoin