抄録
The effects of triazolam, a newly developed derivative of the triazolobenzodiazepines, on the averaged photopalpebral reflex (PPR) as well as on self-assessment, were investigated in comparison with those of nitrazepam in eight healthy male subjects aged from 18 to 32 years (mean: 23.8) using a double-blind, cross -over design. Blood was collected from 4 of the subjects for assays of triazolam and nitrazepam in plasma. The peak latencies of PPR were rapidly prolonged in a dose-dependent manner after the administration of triazolam, with the maximum level at 180-240 min and recovering within 360 min. In comparison with triazolam at 0.25 mg and 0.5 mg, nitrazepam at 5 mg prolonged the peak latencies of PPR to a lesser extent, and with a more gradual recovery to the initial level. The course of changes over time for both the latencies and the plasma concentrations of triazolam and nitrazepam showed a striking mutual resemblance. The plasma concentration of triazolam showed a peak level at 180min after administration and was markedly reduced at 360min. In contrast, nitrazepam showed its peak plasma level at 240min, with almost the same value even at 360min. The most frequently observed self-assessments were drowsiness, vagueness, and weakness. With triazolam, these symptoms were noted markedly and dose-dependently; however, by 360min, the symptoms had almost disappeared. These results suggest that triazolam may possess sufficient hypnotic, anxiolytic, and muscle-relaxant clinical effects which are likely to appear rapidly and markedly, peaking at 180-240min and disappearing almost completely within 360min.
