Guanethidine lowers blood pressure by depleting norepinephrine from sympathetic nerve endings. Its antihypertensive effect can be completely abolished by co-administration of which class of drugs?
- A Thiazide diuretics
- B Non-selective beta-blockers
- C Tricyclic antidepressants ✓
- D Alpha-2 agonists
Correct answer: C. Tricyclic antidepressants
Explanation
Guanethidine must be transported into the sympathetic nerve terminal by the norepinephrine transporter to reach its intracellular site of action. Tricyclic antidepressants potently block this neuronal uptake pump, preventing guanethidine entry and abolishing its effect. Beta-blockers and thiazides do not interfere with neuronal uptake, and alpha-2 agonists act centrally rather than blocking NET-mediated transport.
Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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