Lack of influence of cigarette smoking on triazolam pharmacokinetics.

The influence of cigarette smoking on the pharmacokinetics of a single dose of the triazolobenzodiazepine hypnotic triazolam was evaluated in 12 healthy nonsmoking male volunteers and in 12 male subjects, matched for age, height and weight, who smoked an average of 24 cigarettes a day (range: 15-30). Triazolam kinetics were determined from multiple serum concentrations measured during 15 h after a single 0.5 mg dose. There were no significant differences between nonsmoking controls and cigarette smokers in the peak serum triazolam concentration (4.64 vs 4.73 ng ml-1), the time of peak concentration (0.98 vs 1.0 h after dosage), elimination half-life (2.8 vs 2.5 h), or oral clearance of triazolam (506 vs 627 ml min-1). Likewise there were no significant differences between groups in the extent of triazolam binding to serum protein (18.8 vs 18.5% unbound). Altered pharmacodynamics of triazolam in cigarette smokers are not likely to be explained by altered pharmacokinetics.