Hexamethonium, a ganglion blocker, produces which of the following by its action at parasympathetic ganglia supplying the gut?
- A Reduced GI motility leading to constipation ✓
- B Increased GI motility and diarrhea
- C Increased gastric acid secretion
- D Excessive salivation
Correct answer: A. Reduced GI motility leading to constipation
Explanation
Ganglion blockers like hexamethonium block nicotinic N2 receptors at all autonomic ganglia, interrupting both sympathetic and parasympathetic transmission. In the GI tract, where the dominant resting tone is parasympathetic (promoting motility and secretion), ganglionic blockade effectively removes this drive, resulting in decreased intestinal motility, constipation, and reduced gastric secretion — effects resembling systemic atropinization of the gut.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.