Enhanced sedative effect w/ alcohol. Enhanced euphoric effect of benzodiazepines & benzodiazepine-like agents w/ narcotic analgesics. Increased plasma levels w/ erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir. Decreased plasma levels w/ rifampicin, carbamazepine, phenobarb, pheytoin, St. John's wort. Antipsychotics (neuroleptics), hypnotics, anxiolytics/sedatives, antidepressant agents, narcotic analgesics, anti-epileptic drugs, anaesthetics & sedative antihistamines.