Alcohol and other CNS depressants (benzodiazepines, opioids, antihistamines, antipsychotics) increase sedation/respiratory depression; CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin, ritonavir) may increase levels; CYP3A4 inducers (e.g., rifampicin, carbamazepine, phenytoin, St John’s wort) may reduce effect; caution with antidepressants and muscle relaxants due to additive sedation