Mesantoin

Generic name: mephenytoin
Dosage form: Tablets, USP
Drug class:Hydantoin anticonvulsants

Medically reviewed by Drugs.com. Last updated on Mar 22, 2022.

30163904

Mesantoin®*

(mephenytoin)

tablets, USP

Caution: Federal law prohibits dispensing without prescription.

Mesantoin Description

Mesantoin® (mephenytoin) is 3-methyl 5,5-phenyl-ethyl-hydantoin. It may be considered to be the hydantoin homolog of the barbiturate mephobarbital. Mesantoin® (mephenytoin) has the following structure:

Active Ingredient: mephenytoin, USP

Inactive Ingredients: D&C Red #7 Calcium Lake, gelatin, lactose, starch, stearic acid, and sucrose.

Mesantoin® (mephenytoin) is available in speckled, pale pink 100 mg tablets for oral administration.

Mesantoin - Clinical Pharmacology

Mephenytoin exhibits pharmacologic effects similar to both phenytoin and the barbiturates in antagonizing experimental seizures in laboratory animals. Mephenytoin produces behavioral and electroencephalographic effects in people which are similar to those produced by barbiturates.

The absorption of mephenytoin given orally as a solution of the racemic drug is rapid. Mephenytoin is metabolized stereoselectively. The S-enantiomer is preferentially hydroxylated to give 5-ethyl-3-methyl-5-(4-hydroxyphenyl)-2,4-imidazolidinedione (S-4´-hydroxymephenytoin). The R-enantiomer is primarily N-demethylated to give 5-ethyl-5-phenyl-2,4-imidazolidinedione (R-phenylethylhydantoin) [R-PEH], the active metabolite. Following simultaneous administration of 14C-S-mephenytoin and 3H-R-mephenytoin, 95±3% of the administered 14C radioactivity was recovered in the urine 24 hours after dosing in the form of S-4´-hydrox...