Relationship between single oral dose pharmacokinetics of alprazolam and triazolam

The relationship between the single oral dose pharmacokinetics of alprazolam and triazolam was studied in 10 healthy male volunteers. Each subject took single oral doses of alprazolam 0.8 mg and triazolam 0.5 mg with at least a 2 week interval between each dose. Blood samplings were performed up to 48 h after alprazolam dosing and up to 12 h after triazolam dosing. Plasma concentrations of both drugs were measured by high-performance liquid chromatography. The means +/- standard deviation of the peak plasma concentration, the total area under the plasma concentration-time curve and the elimination half-life of alprazolam were 11.3 +/- 3.1 ng/ml, 232.4 +/- 59.2 ng/h/ml and 16.5 +/- 4.6 h, respectively, and those of triazolam were 3.2 +/- 1.0 ng/ml, 11.8 +/- 5.2 ng/h/ml and 2.5 +/- 1.1 h, respectively. There was no significant correlation between the two drugs in any pharmacokinetic parameters (r = 0.35, 0.25 and 0.50). The present study thus suggests that the single oral dose pharmacokinetics of alprazolam and triazolam do not correlate well in individuals.