Nitrazepam Cimetidine

Ochs HR, Greenblatt DJ, Gugler R, Muntefering G, Locniskar A, Abernethy DR. Cimetidine impairs nitrazepam clearance. Chn Pharmacol Ther 1983 34(2) 227-30. 

Cimetidine inhibits the liver enzymes associated with oxidative metabolism. Hence, the serum levels of most benzodiazepines affected by this metabolic pathway (aiprazoiam, diazepam, cbiordiazepoxide, fiurazepam, nitrazepam, and triazoiam) were found to be increased when cimetidine was co-administered. Benzodiazepines metabolized by glucuronide conjugation (iorazepam, oxazepam, and temazepam) are not affected by cimetidine. Ranitidine probably has no significant interaction with most benzodiazepines. 

The combined serum level of diazepam and its active metabolite, des-methyldiazepam, was found to be increased by 75% in 10 patients who took cimetidine 300 mg four times daily for 2 weeks, but reaction times and other motor and intellectual tests remained unaffected. Other reports describe a rise in the plasma levels and/or AUC of diazepam (associated with increased sedation in one report ) due to cimetidine, and generalised incoordination has also been described in one individual. Cimetidine also raises the serum levels of adinazolam, alprazolam, chlordiazepoxide, clobazam, clorazepate, flu-razepam, nitrazepam, and triazolam, > > > and reduces the clearance of bromazepam. ... 

Cimetidine inhibits the liver enzymes concerned with the metabolism of diazepam, alprazolam, chlordiazepoxide, clomethiazole, clorazepate, flu-razepam, nitrazepam, triazolam, and zaleplon. As a result their clearance from the body is reduced and their serum levels rise. 

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