A first-generation sulfonylurea is known to cause dilutional hyponatraemia and facial flushing after alcohol intake through a shared pharmacodynamic property. That property is:
- A Inhibition of vasopressin secretion from the posterior pituitary
- B Induction of nephrogenic diabetes insipidus
- C Potentiation of antidiuretic hormone action on the collecting duct ✓
- D Inhibition of free water reabsorption in the proximal tubule
Correct answer: C. Potentiation of antidiuretic hormone action on the collecting duct
Explanation
Chlorpropamide potentiates the effect of ADH on the collecting duct, producing a syndrome resembling SIADH with dilutional hyponatraemia, and the same drug also produces flushing after alcohol by an ADH-related mechanism. Tolbutamide, glipizide and gliclazide do not share this property. This dual feature of chlorpropamide is a classic examination point distinguishing it from other sulfonylureas.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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