Methylphenobarbital

Methylphenobarbital (INN), also known as mephobarbital (USAN, JAN) and mephobarbitone (BAN), marketed under brand names such as Mebaral, Mephyltaletten, Phemiton, and Prominal, is a drug which is a barbiturate derivative and is used primarily as an anticonvulsant, but also as a sedative and anxiolytic. It is the N-methylated analogue of phenobarbital and has similar indications, therapeutic value, and tolerability.

Approval History

 * 1935 Mebaral was introduced by Winthrop Pharmaceuticals.
 * 2001 Methylphenobarbital discontinued in the UK.
 * 2003 Mebaral acquired by Ovation Pharmaceuticals (a specialty pharmaceutical company that acquired underpromoted branded pharmaceutical products).
 * 2009 Ovation was acquired by Lundbeck, which now markets Mebaral. However, Lundbeck recently announced that they are abandoning the product because, under the FDA unapproved-drug campaign, FDA is no longer willing to allow it to be grandfathered. A new drug application was never submitted to the FDA to gain marketing approval. The drug will no longer be available when supplies are depleted, which is anticipated by the end of 2011.

Overdose
Symptoms of overdose of mephobarbital include confusion, decrease in or loss of reflexes, somnolence, fever, irritability, hypothermia, poor judgment, shortness of breath or slow/troubled breathing, slow heartbeat, slurred speech, staggering, trouble in sleeping, unusual movements of the eyes, weakness.

Chemistry
Mephobarbital (5-ethyl-1-methyl-5-phenylbarbituric acid) is synthesized according to one of the diagrams used for the phenobarbital synthesis, except one uses methylurea instead.


 * W. Kropp, L. Taub, (1929).