Which of the following best describes the mechanism of action of methyldopa in pregnancy-induced hypertension?

• A Direct arteriolar vasodilatation via potassium channel opening
• B Competitive antagonism of peripheral alpha-1 receptors
• C False neurotransmitter action reducing central sympathetic outflow ✓
• D Inhibition of catechol-O-methyl transferase in adrenergic terminals

Explanation

Methyldopa is converted to alpha-methyl noradrenaline, a false neurotransmitter that is stored and released from central adrenergic neurons, stimulating inhibitory alpha-2 receptors and lowering sympathetic outflow. Its long safety record for mother and fetus makes it a traditional first-line oral agent in India, though sedation, dry mouth, depression and positive Coombs test limit use. It causes no uteroplacental flow compromise.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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