Single dose pharmacokinetics and pharmacodynamics of oral oxazepam during concomitant administration of propranolol and labetalol.

Abstract

1 The oral kinetics of oxazepam after a single 15 mg oral dose was investigated in six healthy volunteers before and during concomitant administration of the ,-adrenoceptor antagonists propranolol (80 mg) and labetalol (200 mg) (racemates). 2 A possible pharmacodynamic interaction between oxazepam and the 13-adrenoceptor antagonists was examined using a simple reaction time test (SRT) and by measurement of postural sway. 3 The kinetics of oxazepam were not affected significantly by propranolol or labetalol, although oxazepam and labetalol share the glucuronidation pathway.4 The SRT was increased by combination of both 0-adrenoceptor antagonists with oxazepam, with the greatest increase after the coadministration of oxazepam with propranolol. Administration of the P-adrenoceptor antagonists alone had no significant effect. 5 Postural sway was affected significantly only by the combination of oxazepam and propranolol.