The rate of hepatic biotransformation is increased in younger children, in pregnant women, in women during menses, and in patients with acute trauma; rate decreases with advancing age. ... Mephenytoin has an active metabolite, nirvanol (5-ethyl-5-phenylhydantoin). /Hydantoin anticonvulsants/
Mephenytoin is N-demethylated by the liver to form a highly toxic compound, 5,5-ethylphenylhydantoin. It is probably that this metabolite at least partly accounts for both the therapeutic and toxic effects of mephenytoin. The N-demethylated /metabolite/ may be excreted in the urine or further metabolized via p-hydroxylation of the phenyl group, conjugated with glucuronic acid, and excreted in the urine.
Human liver was used in investigations of mephenytoin p-hydroxylase, the enzyme presumably responsible for the genetic polymorphism in mephenytoin metabolism. A gas chromatographic assay method was developed to measure p-hydroxylation and N-demethylation which is the other major metabolic pathway. Both reactions were localized in the microsomal fraction and required NADPH. Inhibition of p-hydroxylation by CO, SKF 525-A, and metyrapone was demonstrated. It was concluded that a form of cytochrome P-450 catalyzes the reaction. The velocity of N-demethylation in human liver did not show saturation even at 500 microM substrate concentration. The p-hydroxylation, however, followed Michaelis-Menten kinetics. The Km, determined in five different livers, ranged from 59 to 143 microM. The linearity in Eadie-Hofstee plots was consistent with the involvement of a single catalytic site.
A major metabolite of the antiepileptic drug mephenytoin (3-methyl-5-ethyl-5-phenylhydantoin) has been identified in urine after a single oral dose of 100 mg of mephenytoin in man. Using chemical synthesis, gas chromatography-mass spectrometry, and nuclear magnetic resonance spectroscopy, /investigators/ established its chemical structure as 3-methyl-5-ethyl-5-(4-hydroxyphenyl)hydantoin (4-OH-M) which is a product of aromatic hydroxylation of mephenytoin in man. Quantitative determinations of 4-OH-M in urine of 10 volunteers showed that 43 +/- 7% (SD) of a single oral dose of 100 mg of mephenytoin were eliminated as the glucuronide of this metabolite. Urinary elimination of the demethylated metabolite, 5-ethyl-5-phenylhydantoin (Nirvanol), was low (1% of the dose per 24 hr) emphasizing the importance of 4-OH-M as the major metabolite after a single oral dose of mephenytoin. Other products of mephenytoin hydroxylation (2-OH-M, E-OH-M, or aliphatically hydroxylated 2-OH-ethyl-M) were not detectable under the conditions selected (less than 1 umol/24 hr).
参考文献：M Chen, V Vijay, Q Shi, Z Liu, H Fang, W Tong. 美国食品药品监督管理局批准的药物标签用于研究药物诱导的肝损伤，《药物发现今日》，16(15-16):697-703, 2011. PMID:21624500 DOI:10.1016/j.drudis.2011.05.007
M Chen, A Suzuki, S Thakkar, K Yu, C Hu, W Tong. DILIrank：按人类发展药物诱导肝损伤风险排名的最大参考药物清单。《药物发现今日》2016, 21(4): 648-653. PMID:26948801 DOI:10.1016/j.drudis.2016.02.015
References:M Chen, V Vijay, Q Shi, Z Liu, H Fang, W Tong. FDA-Approved Drug Labeling for the Study of Drug-Induced Liver Injury, Drug Discovery Today, 16(15-16):697-703, 2011. PMID:21624500 DOI:10.1016/j.drudis.2011.05.007
M Chen, A Suzuki, S Thakkar, K Yu, C Hu, W Tong. DILIrank: the largest reference drug list ranked by the risk for developing drug-induced liver injury in humans. Drug Discov Today 2016, 21(4): 648-653. PMID:26948801 DOI:10.1016/j.drudis.2016.02.015
Mephenytoin is absorbed from the GI tract. Following oral administration, the drug has an onset of action of 30 minutes and a duration of action of 24-48 hours. Plasma concentrations required for therapeutic effects are not known; however, total serum concentrations of mephenytoin and its major metabolite of 25-40 ug/mL are reportedly associated with good seizure control without clinical intoxication.
Therapeutic serum concentrations range from 25 to 40 ug/mL (115 to 183 umol/L) for mephenytoin in combination with nirvanol /SRP: its active metabolite/. Time to peak concentration ranges from 45 minutes to 4 hours for mephenytoin and from 16 to 36 hours for nirvanol.
... /A/ single-dose study of mephenytoin (Mesantoin) ... was performed in adult inpatients on stable regimens of other anticonvulsants. Five patients received mephenytoin, 7 mg per kilogram of body weight. Serial blood sampling was performed rigorously. The time to peak concentration (Tmax) for mephenytoin was 1 hour, with a half-life (T 1/2) of 7 hours; the T 1/2 of its metabolite, 5-ethyl-5-phenylhydantion, was 96 hours. ... Saliva accurately represented the unbound fraction for /both/ agents. Mean salivary levels (as percentage of total levels) were 61% for mephenytoin, 73% for its metabolite ... . The implications for therapy are that following mephenytoin administration, the metabolite 5-ethyl-5-phenylhydantoin will provide anticonvulsant effectiveness, with its long half-life producing stable blood levels on simple dose schedules.
[EN] SUBSTITUTED BICYCLIC DIHYDROPYRIMIDINONES AND THEIR USE AS INHIBITORS OF NEUTROPHIL ELASTASE ACTIVITY<br/>[FR] DIHYDROPYRIMIDINONES BICYCLIQUES SUBSTITUÉES ET LEUR UTILISATION EN TANT QU'INHIBITEURS DE L'ACTIVITÉ ÉLASTASE DE NEUTROPHILES
申请人：BOEHRINGER INGELHEIM INT
公开号：WO2014135414A1
公开（公告）日：2014-09-12
This invention relates to substituted bicyclic dihydropyrimidinones of formula (1) and their use as inhibitors of neutrophil elastase activity, pharmaceutical compositions containing the same, and methods of using the same as agents for treatment and/or prevention of pulmonary, gastrointestinal and genitourinary diseases, inflammatory diseases of the skin and the eye and other autoimmune and allergic disorders, allograft rejection, and oncological diseases.
[EN] PROCESSES USEFUL FOR THE SYNTHESIS OF (R)-1-{2-[4'-(3-METHOXYPROPANE-1-SULFONYL)-BIPHENYL-4-YL]-ETHYL}-2-METHYL-PYRROLIDINE<br/>[FR] PROCÉDÉS UTILES POUR LA SYNTHÈSE DE LA (R)-1-{2-[4'-(3-MÉTHOXYPROPANE-1-SULFONYL)-BIPHÉNYL-4-YL]-ÉTHYL}-2-MÉTHYL-PYRROLIDINE
申请人：ARENA PHARM INC
公开号：WO2009128907A1
公开（公告）日：2009-10-22
Processes useful for making a pharmaceutically useful compound according to Formula (I), forms of such a compound, and intermediates useful in such processes are described.
根据公式（I）制备药用化合物的有用过程，以及该化合物的形式和在这些过程中有用的中间体被描述。
Pseudoephedrine-Directed Asymmetric α-Arylation of α-Amino Acid Derivatives
作者：Rachel C. Atkinson、Fernando Fernández-Nieto、Josep Mas Roselló、Jonathan Clayden
DOI：10.1002/anie.201502569
日期：2015.7.27
Available α‐amino acids undergo arylation at their α position in an enantioselective manner on treatment with base of N′‐aryl urea derivatives ligated to pseudoephedrine as a chiral auxiliary. In situ silylation and enolization induces diastereoselective migration of the N′‐aryl group to the α position of the amino acid, followed by ring closure to a hydantoin with concomitant explulsion of the recyclable
[EN] PIPERIDINE OR PIPERAZINE LINKED IMIDAZOLE AND TRIAZOLE DERIVATIVES AND METHODS OF USE THEREOF FOR IMPROVING THE PHARMACOKINETICS OF A DRUG<br/>[FR] DÉRIVÉS D'IMIDAZOLE ET DE TRIAZOLE LIÉS À LA PIPÉRIDINE OU LA PIPÉRAZINE ET LEURS PROCÉDÉS D'UTILISATION POUR AMÉLIORER LA PHARMACOCINÉTIQUE D'UN MÉDICAMENT
申请人：MERCK SHARP & DOHME
公开号：WO2015070367A1
公开（公告）日：2015-05-21
The piperidine or piperazine linked imidazole and triazole derivatives, compositions comprising said compounds, alone or in combination with other drugs, and methods of using the compounds for improving the pharmacokinetics of a drug are provided. The compounds of the invention are useful in human and veterinary medicine for inhibiting CYP3A4 and for improving the pharmacokinetics of a therapeutic compound that is metabolized by CYP3A4.
BENZAZEPINE DERIVATIVE, PROCESS FOR PRODUCING THE SAME, AND USE
申请人：Takeda Chemical Industries, Ltd.
公开号：EP1422228A1
公开（公告）日：2004-05-26
The present invention provides a novel benzazepine derivative represented by formula :
wherein, R1 is a 5- or 6-membered aromatic ring, R2 is lower alkyl group, etc., Y is an optionally substituted imino group, ring A and ring B are independently an optionally substituted aromatic ring, W is formula -W1-X2-W2- (W1 and W2 are independently S(O)m1 (m1 is 0, 1 or 2), etc., and X2 is an optionally substituted alkylene groupetc. ), a preparation method and use thereof.
