A drug that blocks muscarinic receptors in the peripheral nervous system would be classified as:

• A. Sympathomimetic
• B. Sympatholytic
• C. Parasympathomimetic
• D. Parasympatholytic

Answer: (D)

Blocking muscarinic receptors in the peripheral nervous system stops parasympathetic actions at their targets. The parasympathetic system uses acetylcholine to activate muscarinic receptors, so when these receptors are blocked, parasympathetic effects are inhibited and the body shifts toward sympathetic-like responses—heart rate tends to rise, pupils dilate, secretions decrease, and bladder/GI activity is reduced. This profile matches a parasympatholytic effect (anticholinergic). The other terms describe different actions: mimicking sympathetic activity, blocking sympathetic activity, or stimulating parasympathetic activity, none of which fit the mechanism of blocking muscarinic receptors.