Enhance sedative effect w/ alcohol. Enhance the central depressive effect w/ antipsychotics (neuroleptics), hypnotics, anxiolytics/sedatives, antidepressant agents, narcotic analgesics, antiepileptic drugs, anaesth & sedative antihistamines. Enhance euphoria which may lead to increase in psychic dependence w/ narcotic analgesics. CYP450 may enhance the activity of benzodiazepines & benzodiazepine-like agents. Increase plasma levels w/ CYP3A4 inhibitors (erythromycin, clarithromycin, ketoconazole, itraconazole & ritonavir). Decrease plasma levels w/ CYP3A4 inducers (rifampicin, carbamazepine, phenobarb, phenytoin & St. John's wort).