Drug Antihypertensive Therapy: Factors – Possibility of Pregnancy, Age and Race
Possibility of Pregnancy
There is no one drug that is automatically indicated to gradually reduce maternal blood pressure. It is recommended practice to use (or change to) agents that have been studied in controlled clinical trials in pregnancy. At present, these agents are methyldopa, hydralazine, or any of the p-blockers (the best evidence for safety and efficacy existing for atenolol, oxprenolol, and labetalol).
Diuretics are not particularly effective hypotensive agents for pregnant women. Worse, they may increase the risk of low birth weight infants by reducing intravascular volume and uteroplacental perfusion. They may also cause a variable elevation in urate level, which can otherwise be used to monitor for preeclampsia.
Nifedipine has been used successfully to treat acute episodes of severe hypertension in pregnancy, but its use for long-term treatment of mild to moderate hypertension in pregnancy has not been well studied.
Angiotensin-converting enzyme inhibitors have been shown to cause fetal deaths in animal studies and growth retardation in humans. There have been optimistic reports of successful pregnancies in patients treated with angiotensin-converting enzyme (ACE) inhibitors, but no controlled clinical trials. These drugs and other poorly studied agents, such as diltiazem, verapamil, and prazosin, cannot yet be considered suitable for use in human pregnancy.
Antihypertensive drugs taken by a lactating mother are excreted in breast milk in minute amounts. The effects of antihypertensive medications on breast-feeding have not been studied scientifically. At our institution, infants have routinely and successfully breast-fed from mothers receiving methyldopa, hydralazine, and β-blockers. Diuretics are avoided because they can decrease the volume of milk produced.
Age and race
The sympathetic nervous system plays a relatively smaller role in maintaining elevated blood pressure in older patients than in the young. Furthermore, plasma renin activity (and consequently, the vasopressor activity of angiotensin II) tends to fall with age; it is also lower in blacks than in whites. Drugs (such as p-blockers) that tend to lower sympathetic tone and that work more effectively in high renin states may be more effective first choices for young, white patients. Drugs that work best in low renin states may be preferable for blacks and for the elderly.
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