(S)-MEPHENYTOIN Chemical Properties

Melting point:

135-138 °C

Boiling point:

358.94°C (rough estimate)

Density 

1.154±0.06 g/cm3 (20 ºC 760 Torr)

refractive index 

1.6660 (estimate)

storage temp. 

2-8°C

solubility 

DMSO (Slightly), Ethanol (Slightly), Methanol (Slightly)

form 

solid

pka

pKa 8.1 (Uncertain)

color 

off-white

CAS DataBase Reference

50-12-4(CAS DataBase Reference)

EPA Substance Registry System

Mephenytoin (50-12-4)

Safety Information

Hazard Codes 

Xn

Risk Statements 

22-36/37/38

Safety Statements 

26-36

WGK Germany 

2

HS Code 

2933210000

Hazardous Substances Data

50-12-4(Hazardous Substances Data)

Toxicity

LD50 i.p. in mice: 300 mg/kg (Dzhagatspanyan)

MSDS

• Language:English Provider:SigmaAldrich

(S)-MEPHENYTOIN Usage And Synthesis

Description

Mephenytoin is N-methylated at position 3 with an ethyl group replacing one of the phenyl substituents at position 5. It is indicated for focal and jacksonian seizures in patients refractory to less toxic AEDs. Mephenytoin produces more sedation than phenytoin and should be used only when safer drugs have failed, because it is associated with an increased incidence of serious toxicities, such as severe rash, agranulocytosis, and hepatitis. Its N-desmethyl metabolite, 5-phenyl- 5-ethylhydantoin, contributes to both efficacy and toxicity for mephenytoin. The drug is no longer commercially available inside but is still available outside the United States.

Originator

Mesantoin,Sandoz

Uses

Anticonvulsant.

Uses

rac-Mephenytoin is an anticonvulsant agent.

Definition

ChEBI: Mephenytoin is an imidazolidine-2,4-dione (hydantoin) in which the imidazolidine nucleus carries a methyl group at N-3 and has ethyl and phenyl substituents at C-5. An anticonvulsant, it is no longer available in the USA or the UK but is still studied largely because of its interesting hydroxylation polymorphism. It has a role as an anticonvulsant.

Manufacturing Process

23 parts sodium was dissolved in 300 parts of ethanol and added to 160 parts of 5-phenylcyanacetamide in 750 parts of ethanol. A mixture was cooled straight away and a sodium salt of amide precipitated as a white powder. 200 parts of ethyl iodide was added to this mixture and heated for 1.5 hours. The ethanol was distilled off, water was added to the residue and rapidly hardened oil precipitated. After recrystallization from ethanol, 5-ethyl-5- phenylacetamide afforded; MP: 116°C.
100 parts of sodium hydroxide was solved in 500 parts of water and added to 83 parts of bromine by cooling. 5-Ethyl-5-phenylacetamide was added to above prepared mixture. It dissolved quickly, whereupon all mass was heated some time, cooled and stood at room temperature some hours. Then a solution of sodium bisulfite was added before the formed precipitate dissolved. The reaction mixture was filtered, the filtrate was acidified to give rapidly hardened oil. After recrystallization from ethanol 5-ethyl-3-methyl-5-phenylhydantoin was yielded as the bright needles; MP: 201°-202°C.

brand name

Mesantoin (Novartis).

Therapeutic Function

Anticonvulsant, Antiepileptic

Biological Activity

CYP2C19 substrate. Anticonvulsant.

Biochem/physiol Actions

CYP2B6 and CYP2C19 substrate; anticonvulsive, antiepileptic.

Side effects

Side effects, including rash, fever, and fatal blood dyscrasia, prevent the use as an anticonvulsant drug of first choice.

Safety Profile

Poison by ingestion and intraperitoneal routes. Human systemic effects by ingestion: somnolence, hemorrhage, changes in teeth and supporting structures. Human mutation data reported. An experimental teratogen. An FDA proprietary drug used as an anticonvulsant. When heated to decomposition it emits toxic fumes of NOx.

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