Effects of dosing interval on the pharmacokinetic and pharmacodynamic interactions between the oral adsorbent AST-120 and triazolam in humans.

The objective of this study was to evaluate the pharmacokinetic and pharmacodynamic interactions between the oral adsorbent AST-120 and triazolam. In this randomized, cross-over study, 12 healthy volunteers received a single oral dose of triazolam 0.25 mg alone or with AST-120 2 g given 0, 30 or 60 min before triazolam administration. The area under the plasma triazolam concentration-time curve (AUC(0-∞)) significantly decreased with simultaneous AST-120 + triazolam (alone vs simultaneous: 10.9 ± 6.0 vs 6.4 ± 2.6 ng·h/mL, p = 0.003). Triazolam-induced impairment in psychomotor performance assessed by the digit symbol substitution test was significantly attenuated when AST-120 was administered simultaneously. No significant changes in pharmacokinetic and pharmacodynamic parameters were observed when AST-120 was given 30 or 60 min before triazolam administration. Administering AST-120 simultaneously with triazolam affects the pharmacokinetics and pharmacodynamics of triazolam. Dosing AST-120 at least 30 min before triazolam administration may avoid these interactions.