Design and pharmacodynamic evaluation of novel dual release formulations of triazolam.
Triazolam is an effective hypnotic that can cause amnesia and psychomotor performance decrements, particularly after a 0.5 mg dose. Previous pharmacodynamic studies suggested a relationship between these effects and triazolam plasma concentration. A novel dual release bilayer tablet was designed to mimic the onset of action of a 0.25 mg dose and to maintain the duration of a 0.5 mg dose without the side effects associated with the 0.5 mg dose. The immediate release component of the bilayer tablet contained 0.25 mg triazolam while the sustained release component contained 0.15 mg triazolam. Two prototype formulations of the bilayer tablet, differing in rate of release in the sustained release component, were tested against a conventional 0.5 mg triazolam compressed tablet and placebo in a single-dose, double-blind, four-way crossover study in healthy male subjects. Triazolam plasma concentration time profile was obtained over 12 hours following single administration of each treatment. Effects of triazolam on central nervous system function were evaluated using psychomotor performance tests, immediate and delayed recall tests and rating of sedation. The triazolam plasma concentrations were not significantly different among the active drug treatments, although the dual release tablets did give the expected profiles. There were significant differences in triazolam effects on memory and psychomotor performance. The slowest releasing dual-release tablet showed significantly less psychomotor impairment and memory deficit than the conventional tablet. There was no difference in sedation among the active drug treatments.(ABSTRACT TRUNCATED AT 250 WORDS)