Methyldopa hemodynamic effects

An important aspect of a-methyldopa s hemodynamic effects is that renal blood flow and glomerular filtration rate are not reduced. As occurs with most sympathetic depressant drugs and vasodilators, long-term therapy with a-methyldopa leads to fluid retention, edema formation, and plasma volume expansion. While data conflict somewhat, it is generally thought that a-methyldopa suppresses plasma renin activity. 

Methyldopa and clonidine produce slightly different hemodynamic effects clonidine lowers heart rate and cardiac output more than does methyldopa. This difference suggests that these two drugs do not have identical sites of action. They may act primarily on different populations of neurons in the vasomotor centers of the brain stem. 

The primary hemodynamic alteration responsible for the hypotensive effects of a-methyldopa remains in dispute. A en the patient is supine, the reduction in blood pressure produced by a-methyldopa correlates best with a decrease in peripheral vascular resistance, cardiac output being only slightly reduced. When the patient is upright, the fall in blood pressure corresponds more closely with a reduced cardiac output. 

Many agents can be used to treat chronic hypertension in pregnancy (Table 13-7). Methyldopa is considered the drug of choice. Data indicate that uteroplacental blood flow and fetal hemodynamics are stable with methyldopa. Moreover, it is viewed as very safe based on long-term follow-up data (7.5 years) that have not demonstrated adverse effects on childhood development. /S-Blockers, labetalol, and... 

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