Which Schedule IV drug is indicated for insomnia and has a non-benzodiazepine mechanism?

• A. Pemoline
• B. Zaleplon
• C. Phentermine
• D. Diphenoxylate

Answer: (B)

Non-benzodiazepine hypnotics designed for insomnia belong to the Z-drug class and are Schedule IV. They work on the GABA-A receptor but are selective for the BZ1 (omega-1) subsite, producing sleep-promoting effects with typically less anxiolytic or muscle-relaxant activity than traditional benzodiazepines. Zaleplon fits this profile: it acts as a hypnotic with a very short half-life, so it helps with sleep onset while minimizing next-day sedation. This makes it a good option for insomnia characterized mainly by difficulty falling asleep.

The other drugs listed are not used for insomnia. Pemoline is a stimulant affecting wakefulness; phentermine is a weight-loss stimulant; diphenoxylate is an opioid antidiarrheal. They do not provide the targeted, non-benzodiazepine hypnotic effect described.