Effect of after-dinner administration on the pharmacokinetics of oral flunitrazepam and loprazolam.

The pharmacokinetics of two benzodiazepine hypnotics, flunitrazepam and loprazolam, was determined on two occasions in two groups of eight healthy volunteers. Single 2-mg oral doses of either drug were given in the fasting state at morning on one occasion and after a standard dinner at night on another. Compared with administration of drugs in the fasting state, administration of the drugs after dinner decreased peak plasma concentrations, delayed the time to reach maximum concentration, and prolonged the absorption half-life. The extent of absorption was reduced for flunitrazepam but not for loprazolam. The elimination half-life of both flunitrazepam and loprazolam was not changed in the two conditions. These changes may be of clinical significance because they can delay and reduce the effects of the drugs.