A patient with SIADH and persistent hyponatremia despite fluid restriction is started on demeclocycline. Its therapeutic mechanism in SIADH involves:
- A Antagonism of V2 vasopressin receptors in the collecting duct
- B Stimulation of atrial natriuretic peptide release
- C Induction of nephrogenic diabetes insipidus by antagonizing ADH action ✓
- D Inhibition of sodium reabsorption in the distal tubule
Correct answer: C. Induction of nephrogenic diabetes insipidus by antagonizing ADH action
Explanation
Demeclocycline, a tetracycline antibiotic, is used in SIADH to induce nephrogenic diabetes insipidus. It impairs ADH action on the collecting duct by interfering with intracellular cAMP signaling, thereby promoting free water excretion. It is reserved for cases refractory to fluid restriction and vaptans.
Reference: Katzung Basic & Clinical Pharmacology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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