Methyldopa

• Methyldopa (Aldomet) 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 (Aldomet) 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 stroke 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

  • Parkinsonian signs

  • Reduced libido

  • 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 positive Coombs' develop hemolytic anemia (requiring immediate discontinuation of the drug)

Category: Pharmacology Notes