Midazolam produces its sedative and amnestic effects primarily by which mechanism?

• A. Potentiating GABA-A receptor chloride channel, acting as a positive allosteric modulator
• B. Blocking voltage-gated calcium channels
• C. Directly activating GABA-B receptors
• D. Inhibiting acetylcholine at muscarinic receptors

Answer: (A)

Midazolam works by boosting the brain’s GABAergic inhibition through a positive allosteric action on the GABA-A receptor chloride channel. As a benzodiazepine, it binds to the benzodiazepine site on the GABA-A receptor complex and increases the receptor’s affinity for GABA, which raises the frequency of chloride channel openings. This enhanced chloride influx hyperpolarizes neurons and dampens their activity, producing sedation and amnesia. The drug does not directly activate the receptor, nor does it affect GABA-B receptors, calcium channels, or muscarinic receptors, which is why those mechanisms aren’t correct for midazolam’s primary effects.