-
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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