Which benzodiazepine is well known for forming a pharmacologically active metabolite?

Diazepam is metabolized via hepatic CYP450 oxidation into active metabolites, most notably desmethyldiazepam (nordiazepam), which has a long half-life and contributes to diazepam's prolonged sedative effects. Lorazepam, by contrast, is metabolized by glucuronidation directly to inactive metabolites — a reason it's often preferred in patients with hepatic impairment.