- Methyldopa is an antihypertensive medication primarily used to treat high blood pressure (hypertension), especially during pregnancy.
- It is a centrally acting alpha-2 adrenergic agonist that works by stimulating receptors in the brain to reduce sympathetic nerve signals, leading to a decrease in blood vessel constriction and heart rate, thereby lowering blood pressure.
Chemical Structure & Formula
- Chemical Formula: C₁₀H₁₃NO₄
- Structure:
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Mechanism of Action (Detailed)
- Methyldopa is a prodrug that is converted to α-methylnorepinephrine, which acts as a central α2 agonist in the brain.
- Stimulates α2 receptors in the CNS → Inhibits sympathetic outflow → Reduces norepinephrine release → Decreased blood pressure.
- Also has mild peripheral dopamine agonist activity, which may improve renal blood flow.
Physiological Effects
- Cardiovascular: Decreases BP without significantly affecting heart rate.
- CNS: Causes sedation due to central α2 activation.
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Side Effects of Methyldopa
- Sedation & Drowsiness
- Depression (long-term use)
- Hemolytic anemia (rare, positive Coombs test)
- Lupus-like syndrome
Clinical Uses of Methyldopa
- Hypertension in pregnancy (first-line).
- Chronic hypertension (alternative to other antihypertensives).
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