Triazolam disposition

Abstract

Triazolam (T) is a new, potent hypnotic with a short duration of action in man. After an 0.88-mg oral dose of T-14C in six male subjects, mean recovery of 14C radioactivity was 85% in urine and 8% in feces. The major urinary metabolites were alpha-hydroxytriazolam (alpha-HT) and 4-hydroxytriazolam (4-HT), accounting for 69% and 11% of the urinary 14C, and these were mostly in conjugated form. alpha, 4-Dihydroxytriazolam and three dichlorotriazolylbenzophenone analogs were minor metabolites. At least 85% of the dose was rapidly absorbed; mean absorption half-life (t1/2A) was 2.8 min. After reaching a mean peak plasma level (Cmax) of 8.8 ng/ml at mean time (tmax) of 1.3 hr, plasma T decreased rapidly with a mean elimination half-life (t1/2E) of 2.3 hr. The remainder of the plasma 14C consisted predominantly of glucuronides of alpha-HT and 4-HT. Mean plasma parameters for these metabolites were as follows: alpha-HT-glucuronide, t1/2E = 3.9 hr, tmax = 1.3 hr, Cmax = 6.1 ng/ml; 4-HT-glucuronide, t1/2E = 3.8 hr, tmax = 2.5 hr, Cmax = 6.1 ng/ml. Nonconjugated alpha-HT and 4-HT were present in plasma but in insufficient amounts for kinetic analysis. The results are consistent with the short duration of action.