Medazepam

Medazepam is a drug that is a benzodiazepine derivative. It possesses anxiolytic, anticonvulsant, sedative, and skeletal muscle relaxant properties. It is known by the following brand names: Azepamid, Nobrium, Tranquirax (mixed with Bevonium), Rudotel, Raporan, Ansilan and Mezapam.^[1] Medazepam is a long-acting benzodiazepine drug. The half-life of medazepam is 36 – 200 hours.^[2]

Benzodiazepine drugs including medazepam increase the inhibitory processes in the cerebral cortex by allosteric modulation of the GABA receptor.^[3] Benzodiazepines may also act via micromolar benzodiazepine-binding sites as Ca²⁺ channel blockers and significantly inhibited depolarization-sensitive calcium uptake in experiments with cell components from rat brains. This has been conjectured as a mechanism for high dose effects against seizures in a study.^[4] It has major active benzodiazepine metabolites, which gives it a more prolonged therapeutic effects after administration.^[5]

Medazepam can be synthesized in various ways. One is via the reduction of the carbonyl group in diazepam (lacking methyl in Ex 1) by lithium aluminium hydride. N.B. If diazepam is reduced with LAH as in Ex 9, actually the product produced is 7-chloro-1-methyl-5-phenyl-1,2,4,5-tetrahydro-3H-1,4-benzodiazepine, not medazepam.

A second way of making medazepam consists of the initial reduction of the carbonyl group by lithium aluminum hydride into 7-chloro-5-phenyl-2,3-dihydro-1H-1,4-benzodiazepin-2-one—the first intermediate product in the synthesis of diazepam—which is synthesized by the cyclocondensation of 2-amino-5-chlorobenzophenone with glycine ethyl ester into 7-chloro-2,3-dihydro-5-phenyl-1H-1,4-benzodiazepine, and the subsequent methylation of the secondary amine nitrogen atom of the resulting product by methyl iodide, using sodium hydride as a base.

A third method of making medazepam consists of a new way of making 7-chloro-2,3-dihydro-5-phenyl-1H-1,4-benzodiazepine, which consists in heterocyclization of 1-(2,5-dichlorophenyl)-1-phenylimine with ethylenediamine. The starting 1-(2,5-dichlorophenyl)-1-phenylimine is synthesized by the reaction of 2,5-dichlorobenzonitrile with phenylmagnesium bromide.

A fourth method of making medazepam from 4-chloro-N-methylaniline is suggested. The last is reacted with aziridine (or ethylene imine) in the presence of aluminum chloride, giving N-(4-chlorophenyl)-N-methylethylenediamine.^[7] Acylation of the resulting product with BzCl gives the respective amide, which cyclizes into the desired medazepam using phosphorus oxychloride.

A fifth method also exists:

• Benzodiazepine

• Benzodiazepine withdrawal syndrome

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• Inchem – Medazepam

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