The pharmacokinetic profile of oxazepam

Oxazepam has the shortest half life of the benzodiazepines and does not form any active metabolites. Its pharmacokinetic properties in healthy volunteers, uremic patients and dogs are reviewed. In normal man half lives between 6 and 25 hours are obtained. The drug is completely absorbed and steady state concentrations develop after multiple doses. In uremic patients the terminal half life of oxazepam in plasma was prolonged to 24-91 hours. However the clearance of oxazepam was not significantly decreased in this patient group and similar doses as in normal subjects are recommended. There was a marked retention of the water soluble oxazepam conjugate in the uremic patients but no pharmacological effect could be detected. In the uremic patients, as in dogs, secondary plasma concentration peaks were seen after single doses. In uremic patients, fecal excretion of oxazepam was increased. In the dog one third of a single intravenous dose was recovered in the bile. Thus enterohepatic cycling may occur in the dog and in uremic patients.