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Mephenytoin

Mephenytoin structure

CAS No.: 50-12-4

Chemical Name:: Mephenytoin

Synonyms: Epilan;Epiazin;Methoin;Metydan;Sacerno;Insulton;Fenantoin;Mesantoin;Mesontoin;NSC-34652

CBNumber:: CB0225135

Molecular Formula:: C12H14N2O2

Molecular Weight:: 218.25

MDL Number:: MFCD00270025

MOL File:: 50-12-4.mol

MSDS File:: SDS

TDS File:: TDS

Last updated:2026-05-27 17:23:25

Product description	Number	Pack Size	Price
Mephenytoin	M3673	10MG	$129
(+/-)-Mephenytoin 97%	MT-16572	0.01g	$376
(+/-)-Mephenytoin 97%	MT-16572	0.01g	$376
Mephenytoin ≥98%(HPLC)	3276	10	$282
rac-Mephenytoin	M224985	5mg	$90

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Mephenytoin 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)
pka	pKa 8.1 (Uncertain)
form	solid
color	off-white
InChI	1S/C12H14N2O2/c1-3-12(9-7-5-4-6-8-9)10(15)14(2)11(16)13-12/h4-8H,3H2,1-2H3,(H,13,16)
InChIKey	GMHKMTDVRCWUDX-UHFFFAOYSA-N
SMILES	CCC1(NC(=O)N(C)C1=O)c2ccccc2
CAS DataBase Reference	50-12-4(CAS DataBase Reference)
EWG's Food Scores	1
FDA UNII	R420KW629U
ATC code	N03AB04,N03AB54
EPA Substance Registry System	Mephenytoin (50-12-4)
UNSPSC Code	12161501

SAFETY

Risk and Safety Statements

Symbol(GHS)	GHS07
Signal word	Warning
Hazard statements	H302-H315-H319-H335
Precautionary statements	P261-P305+P351+P338
target organs	Respiratory system
PPE	dust mask type N95 (US), Eyeshields, Gloves
Hazard Codes	Xn
Risk Statements	22-36/37/38
Safety Statements	26-36
WGK Germany	2
HS Code	2933210000
Storage Class	11 - Combustible Solids
Hazard Classifications	Acute Tox. 4 Oral Eye Irrit. 2 Skin Irrit. 2 STOT SE 3
Hazardous Substances Data	50-12-4(Hazardous Substances Data)
Toxicity	LD50 i.p. in mice: 300 mg/kg (Dzhagatspanyan)

Mephenytoin price More Price(12)

Manufacturer	Product number	Product description	CAS number	Packaging	Price	Updated	Buy
TCI Chemical	M3673	Mephenytoin	50-12-4	10MG	$129	2026-04-30	Buy
AHH	MT-16572	(+/-)-Mephenytoin 97%		0.01g	$376	2026-05-26	Buy
AHH	MT-16572	(+/-)-Mephenytoin 97%		0.01g	$376	2026-05-25	Buy
Tocris	3276	Mephenytoin ≥98%(HPLC)	50-12-4	10	$282	2021-12-16	Buy
TRC	M224985	rac-Mephenytoin	50-12-4	5mg	$90	2021-12-16	Buy

Product number	Packaging	Price	Buy
M3673	10MG	$129	Buy
MT-16572	0.01g	$376	Buy
MT-16572	0.01g	$376	Buy
3276	10	$282	Buy
M224985	5mg	$90	Buy

Mephenytoin Chemical Properties,Uses,Production

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.

Mephenytoin synthesis

Synthesis of Mephenytoin from 2,4-Imidazolidinedione, 5-ethyl-5-phenyl-, (+-)- and Iodomethane

Mephenytoin Preparation Products And Raw materials

Raw materials

Cyanide, Quant Test Strips Dilute hydrochloric acid Propiophenone POTASSIUM CYANIDE Ammonium carbonate

Sodium bisulfite Sodium MEPHOBARBITAL 1-(1-cyano-1-phenylpropyl)-3-methylurea 2,4-Imidazolidinedione, 5-ethyl-5-phenyl-, (+-)-

Methylamine Methylurea Iodomethane N,N-Dimethylformamide dimethyl acetal

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Preparation Products

Mephenytoin Suppliers

Global( 117)Suppliers

Supplier	Tel	Email	Country	ProdList	Advantage
Shaanxi Dideu New Materials Co. Ltd	+86-18192503167 18192503167;	1036@dideu.com	China	7917	58
TargetMol Chemicals Inc.	+1-781-999-5354; +17819995354	marketing@targetmol.com	United States	32466	58
InvivoChem	+1-708-310-1919 +1-13798911105	sales@invivochem.cn	United States	6391	58
Nantong HI-FUTURE Biology Co., Ltd.	+undefined18051384581	sales@chemhifuture.com	China	3135	58
DAYANG CHEM (HANGZHOU) CO.,LTD	+86-88938639 +86-17705817739	info@dycnchem.com	China	53802	58
Chongqing jooe co., ltd	+undefined86-15223382610	info@jooe.com	China	15976	58
Mainchem Co., Ltd.	+86-0592-6210733	sale@mainchem.com	China	32343	55
3B Pharmachem (Wuhan) International Co.,Ltd.	821-50328103-801 18930552037	3bsc@sina.com	China	15838	69
WUHAN SUN-SHINE BIO-TECHNOLOGY Co., Ltd.	17702719238 18971495150;	sales@sun-shinechem.com	China	1157	64
China DongFan Chemical Co.,LTD	86-0571-85151182		China	5691	66

Supplier	Advantage
Shaanxi Dideu New Materials Co. Ltd	58
TargetMol Chemicals Inc.	58
InvivoChem	58
Nantong HI-FUTURE Biology Co., Ltd.	58
DAYANG CHEM (HANGZHOU) CO.,LTD	58
Chongqing jooe co., ltd	58
Mainchem Co., Ltd.	55
3B Pharmachem (Wuhan) International Co.,Ltd.	69
WUHAN SUN-SHINE BIO-TECHNOLOGY Co., Ltd.	64
China DongFan Chemical Co.,LTD	66

View Lastest Price from Mephenytoin manufacturers

Update time	Product	Price	Min. Order	Purity	Supply Ability	Manufacturer
2026-04-21	Mephenytoin 50-12-4	US $52.00-133.00 / mg		99.91%	10g	TargetMol Chemicals Inc.
2025-12-01	Synephrine hydrochloride 50-12-4	US $0.00-0.00 / KG	1KG	98	10000KGS	Shaanxi Dideu New Materials Co. Ltd
2021-08-12	(S)-MEPHENYTOIN 50-12-4	US $15.00-10.00 / KG	1KG	99%+ HPLC	Monthly supply of 1 ton	Zhuozhou Wenxi import and Export Co., Ltd

Mephenytoin
50-12-4
US $52.00-133.00 / mg
99.91%
TargetMol Chemicals Inc.

Synephrine hydrochloride
50-12-4
US $0.00-0.00 / KG
98
Shaanxi Dideu New Materials Co. Ltd

(S)-MEPHENYTOIN
50-12-4
US $15.00-10.00 / KG
99%+ HPLC
Zhuozhou Wenxi import and Export Co., Ltd

Mephenytoin Spectrum

(S)-MEPHENYTOIN(50-12-4)¹HNMR

50-12-4(Mephenytoin)Related Search:

Voriconazole 4-HYDROXY MEPHENYTOIN Mephenytoin 4-HYDROXY MEPHENYTOIN-D3,4-HYDROXY MEPHENYTOIN-D3 5-Phenylhydantoin

(S)-Mephenytoin (R)-(-)-MEPHENYTOIN,(R)-MEPHENYTOIN,(R)-(-)-MEPHENYTOIN,(R)-MEPHENYTOIN (R)-1-METHYLMEPHENYTOIN RAC MEPHENYTOIN-D3,RAC MEPHENYTOIN-D3 (+/-)-N-3-Benzylnirvanol

DESMETHYL MEPHENYTOIN,DESMETHYL MEPHENYTOIN N-DESMETHYL MEPHENYTOIN-D5,N-DESMETHYL MEPHENYTOIN-D5 (+/-)-4'-METHOXYMEPHENYTOIN (S)-5-ETHYL-3-METHYL-5-PHENYLHYDANTOIN=(S)-MEPHENYTOIN,(S)-5-ETHYL-3-METHYL-5-PHENYLHYDANTOIN=(S)-MEPHENYTOIN S-[4-14C]MEPHENYTOIN,S-[4-14C]MEPHENYTOIN

(4-ETHYL-2,5-DIOXO-4-PHENYLIMIDAZOLIDIN-1-YL)ACETIC ACID (2,5-DIOXO-3',4'-DIHYDRO-1H,2'H-SPIRO[IMIDAZOLIDINE-4,1'-NAPHTHALEN]-1-YL)ACETIC ACID (2,5-DIOXO-2',3'-DIHYDRO-1H-SPIRO[IMIDAZOLIDINE-4,1'-INDEN]-1-YL)ACETIC ACID

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(S)-(+)-5-ETHYL-3-METHYL-5-PHENYL-2,4-IMIDAZOLIDINEDIONE (S)-(+)-5-ETHYL-3-METHYL-5-PHENYLHYDANTOIN (S)-5-ETHYL-3-METHYL-5-PHENYLHYDANTOIN (S)-(+)-MEPHENYTOIN (+/-)-5-ETHYL-3-METHYL-5-PHENYL-2,4-IMIDAZOLIDINEDIONE (+/-)-5-ETHYL-3-METHYL-5-PHENYLHYDANTOIN (+/-)-MEPHENYTOIN MEPHENYTOIN Epiazin Epilan Fenantoin Gerot-epilan Hydantoin, 5-ethyl-3-methyl-5-phenyl- Insulton mephenetoinum Mephentoin Mesantoin Mesdontoin Mesontoin Methoin Methyl hydantoin Methylphenetoin Metydan NSC-34652 Phenantoin Phenylethylmethylhydantoin Sacerno Sedantional Sedantoin Sedantoinal Triantoin 2,4-Imidazolidinedione, 5-ethyl-3-methyl-5-phenyl- 3-Ethylnirvanol 3-Methyl-5,5-ethylphenylhydantoin 3-Methyl-5,5-phenylethylhydantoin 3-Methyl-5-ethyl-5-phenylhydantoin 5-Ethyl-3-methyl-5-phenyl-2,4(3H,5H)-imidazoledione 5-ethyl-3-methyl-5-phenyl-4-imidazolidinedione 5-ethyl-3-methyl-5-phenyl-hydantoi 5-Ethyl-3-methyl-5-phenylimidazolidin-2,4-dione 5-Ethyl-5-fenyl-3-methylhydantoin (±)-5-Ethyl-3-methyl-5-phenyl-2,4-imidazolidinedione, (±)-5-Ethyl-3-methyl-5-phenylhydantoin DL-Mephenytoin (5R)-5-Ethyl-3-methyl-5-phenyl-2,4-imidazolidinedione (5R)-5-Ethyl-3-methyl-5-phenylhydantoin (5R)-5α-Ethyl-3-methyl-5-phenylhydantoin 5-ethyl-3-methyl-5-phenyl-imidazolidine-2,4-dione 5-Ethyl-3-methyl-5-phenethylhydantoin MEPHENYTOIN; METHOIN; MESANTOIN; PHENANTOIN; METHYLPHENETOIN; INSULTON. 5-ethyl-3-methyl-5-phenylimidazolidine-2,4-dione Mephenytoin (250 mg) Mephenytoin-d3 (S)-MEPHENYTOIN USP/EP/BP Mephenitoin rac-Mephenytoin/Mephenytoin Mephenytoin, 10 mM in DMSO (±)-Mephenytoin (±)-Mephenytoin, CAS 50-12-4