A comparison of the acute behavioral effects of flunitrazepam and triazolam in healthy volunteers.

Flunitrazepam is an hypnotic benzodiazepine marketed in different European countries. Epidemiological studies have shown that it is frequently abused by opioid addicts. In a survey, "liking" scores for flunitrazepam in methadone maintenance patients were higher than ratings for other benzodiazepines. A double-blind, placebo controlled, crossover clinical trial was conducted to assess the acute behavioral effects of flunitrazepam (0.50 and 2 mg) and triazolam (0.25 and 0.50 mg) in healthy male volunteers. Drug effects on physiological measures, psychomotor performance, and subjective rating scales, including specific questionnaires to evaluate abuse liability (e.g., ARCI or "liking" scores), were assessed before and 6 h after drug administration. Flunitrazepam 2 mg produced the most intense disruptive effects on all the performance tasks, triazolam 0.50 impaired performance except balance. All study drugs at all doses produced sedation symptoms in all or part of the subjective effects questionnaires. Only flunitrazepam 2 mg induced significative increases in some of the scales ("liking", "good effects", "high") that could be related to a possible abuse potential. The results seem to indicate that flunitrazepam, when administered to healthy subjects, produces some pleasurable subjective feelings, that could indicate a higher abuse liability of this drug as compared with other benzodiazepines.