What class of drugs enhances GABA-A receptor activity to promote sleep and what are common examples?

• A. Benzodiazepine receptor agonists; temazepam, triazolam, diazepam, lorazepam.
• B. Barbiturate receptor agonists; phenobarbital, pentobarbital, amobarbital, secobarbital.
• C. Antihistamines; diphenhydramine, doxylamine, hydroxyzine, promethazine.
• D. Orexin receptor agonists; suvorexant, filorexant, lemborexant, almorexant.

Answer: (A)

GABA-A receptor positive modulation is the mechanism behind many sleep-promoting drugs. When a drug binds to the benzodiazepine site on the GABA-A receptor, it makes the receptor more responsive to the natural inhibitory neurotransmitter GABA. This increases chloride ion flow into the neuron, hyperpolarizing it, and reducing brain activity enough to produce sedation and promote sleep. Because of this action, drugs that are benzodiazepine receptor agonists are effective as hypnotics. Common examples include temazepam, triazolam, diazepam, and lorazepam, which are used to help with sleep onset and maintenance.

Other options don’t fit this mechanism. Barbiturate-type agents also enhance GABA effects but at a different binding site and with a higher risk profile. Antihistamines promote sleep primarily through histamine blockade, not by boosting GABA-A activity. Orexin receptor antagonists promote sleep by inhibiting wake-promoting signals rather than enhancing GABAergic inhibition.