Serum medazepam, diazepam, and N-desmethyldiazepam levels after single and multiple oral doses of medazepam.

20 mg of medazepam were taken by mouth by 9 healthy volunteers in an acute absorption study. About a 10-fold variation was found during the first 6 hours after the drug in individual serum medazepam, diazepam, and N-desmethyldiazepam levels. In a subacute study 10 mg of medazepam t.i.d. was given to 10 institutionalized mentally subnormal adults with emotional disorders. After 14 days' treatment serum N-desmethyldiazepam levels were generally above 800 ng/ml, 7 to 8 times higher than the serum medazepam or diazepam levels measured 12 hours after the last dose. No correlation was observed between the serum concentration and efficacy of medazepam.