Nordiazepam

What it isDesmethyldiazepam — the shared active metabolite of diazepam, chlordiazepoxide, clorazepate, and halazepam.

Why it mattersIt is why those benzodiazepines behave as one very-long-acting family: whatever the parent, days-long nordiazepam accumulates underneath.

What it changesAccumulation is the clinical point — hangover sedation, falls in the elderly, and slow self-tapering washout after discontinuation.