Absorption of diazepam in man following rectal and parenteral administration.
Serum concentrations of diazepam and N-desmethyldiazepam were measured in six adult patients following administration of 10 mg diazepam in solution by the rectal, intravenous, and intramuscular routes. Maximum serum concentrations of 121--200 ng/ml were recorded from 10 to 20 min. after the rectal instillation, whereas following intramuscular injection the levels rose slowly and irregularly, reaching a maximum (62--186 ng/ml) in 1 to 24 hours. The bioavailability of diazepam given by rectal instillation was found to be 50 +/- 17 per cent (mean +/- S. D.) as compared with the intravenous administration. The possible reasons for the low bioavailability are discussed. It is concluded that administration by rectal tube provides a useful alternative to the tablets (and intramuscular injections) when a rapid onset of effect of the drug is wanted, and when intravenous administration is not applicable or practical.
D000042:Absorption; D000328:Adult; D001682:Biological Availability; D003975:Diazepam / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D007275:Injections, Intravenous; D007408:Intestinal Absorption; D008297:Male; D008875:Middle Aged; D012007:Rectum; D013488:Suppositories
D013488:Suppositories; D003975:Diazepam