Repeated administration of buspirone: Absence of pharmacodynamic or pharmacokinetic interaction with triazolam

The present study was designed to evaluate possible pharmacokinetic and pharmacodynamic interactions between buspirone administered repeatedly and triazolam given acutely. Ten healthy male volunteers participated in the study and received 0.25 mg of triazolam orally after a one-week pretreatment with either placebo or buspirone 5 mg t.i.d. The study design was double-blind and crossover, the subjects receiving two times triazolam after the random administration of buspirone or placebo, each treatment period being separated by a washout period of 1 week. Plasma triazolam concentrations were measured by a radio-receptor assay using 3H-flunitrazepam as radioligand. Psychomotor effects of triazolam were measured through subjective self rating scales and various cognitive tests exploring concentration, memory and psychomotor skills. Overall, the results of the study failed to demonstrate any significant difference in triazolam subjective or objective effects as well as in triazolam plasma concentrations after a one-week pretreatment with either placebo or buspirone 15 mg daily. They do suggest that clinically relevant interactions are unlikely to appear when buspirone at moderate dosage is co-prescribed with acute doses of triazolam, though these data do not exclude the possibility of pharmacokinetic interactions between the two drugs. Finally our data also suggest the need for more specific studies in order to demonstrate a possible improvement of psychomotor functions after buspirone administration.