Midazolam exerts its sedative and anxiolytic effects primarily by which mechanism?

• A. Enhancing GABA-A receptor activity at the benzodiazepine binding site
• B. Directly activating GABA-A receptors
• C. Inhibiting serotonergic receptors
• D. Blocking nicotinic acetylcholine receptors

Answer: (B)

Midazolam works by enhancing the activity of GABA-A receptors through the benzodiazepine binding site. It acts as a positive allosteric modulator, meaning it increases the effect of GABA when GABA is present by making the chloride channel open more readily or more frequently. This boosts inhibitory neurotransmission, leading to sedation and anxiolysis. It does not directly activate GABA-A receptors on its own; without GABA, the drug’s effect is minimal. In contrast, direct receptor activation would occur if a drug could open the chloride channel without GABA, which is not how benzodiazepines function.