THE PHARMACOKINETICS AND PHARMACODYNAMICS OF SUBLINGUAL AND ORAL ALPRAZOLAM IN THE POSTPRANDIAL STATE

We gave 12 healthy male volunteers 1 mg of alprazolam or placebo on three occasions after a standard breakfast in a double-blind, randomized, single-dose, three-way crossover study. The three trials were: (a) oral alprazolam and sublingual placebo; (b) oral placebo and sublingual alprazolam; (c) placebo by both routes. Plasma alprazolam concentrations during 24 h after each dose were measured by electron-capture gas-liquid chromatography. Peak plasma concentrations were reached later after sublingual than oral dosage (2.8 vs 1.8 h, P < 0.01). Other kinetic variables were not significantly different: peak plasma concentration, 11.3 vs 12.0 ng.ml-1; elimination half-life, 12.5 vs 11.7 h; and total area under the plasma concentration versus time curve, 197 vs 186 h.ng.ml-1. Pharmacodynamic measures showed that sublingual and oral alprazolam both produced sedation, fatigue, impaired digit symbol substitution, slowing of reaction time, and impairment of the acquisition and recall of information. These changes were initially observed at 0.5 h after dosage and lasted up to 8 h. In general the two routes were significantly different from placebo but not from each other.