Alpha-Methyl Dopa (Sympatholytic)
[meth il doe' pa]

  • Methyldopa is a prodrug which is metabolized to the active agent, alpha-methylnorepinephrine.

  • Alpha-methylnorepinephrine acts in the brain, inhibiting adrenergic outflow from the brainstem. Inhibition of sympathetic outflow results in a decrease in blood pressure.

  • Methyldopa produces no change in cardiac output in younger patients, but in older patients a decline in cardiac output results from reduced heart rate and stroke volume. The reduction in stoke volume occurs due to increased venous pooling (decreased preload).

  • Since renal blood flow and function is maintained during methyldopa treatment, methyldopa maybe valuable in managing hypertensive patients with renal insufficiency.

  • Adverse Effects:

    • Dry Mouth

    • Reduced libido

    • Parkinsonian signs

    • Hyperprolactinemia (gynecomastia, galactorrhea)

    • Bradycardia (in patients with SA nodal abnormality)

    • Hepatoxicity (avoid in patients with hepatic disease)

    • positive Coombs' test (20%)\

    • 1-5% of those with postive Coombs' develop hemolytic anemia (requiring immediate discontinuation of the drug)


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