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Calcium-entry blocking agents in the treatment of systemic hypertension
Insights
Calcium-entry blockers like verapamil and nifedipine effectively lower blood pressure and are valuable for hypertension treatment. They offer an alternative when standard drugs are contraindicated, with nifedipine showing promise in combination therapy.
Area of Science:
- Pharmacology
- Cardiovascular Medicine
- Hypertension Management
Background:
- Calcium-entry blockers act on arterial resistance vessels, similar to established vasodilators.
- Their efficacy in treating hypertension has been a focus of clinical research.
Purpose of the Study:
- To evaluate the effectiveness of calcium-entry blockers, specifically verapamil and nifedipine, in managing hypertension.
- To compare their effects with existing antihypertensive agents and assess their side effect profiles.
Main Methods:
- Controlled studies were conducted to assess blood pressure reduction.
- Combination therapy effects with beta-blockers, alpha-methyldopa, and diuretics were investigated.
- Incidence of adverse effects and impact on renin secretion and sodium retention were monitored.
Main Results:
- Verapamil and nifedipine demonstrated effectiveness in lowering blood pressure as monotherapy.
- Nifedipine's antihypertensive effect was additive with beta-blockers and effective in "third step" therapy.
- Unlike other vasodilators, nifedipine caused only moderate renin stimulation, and verapamil did not increase renin release; neither drug induced sodium retention.
- Both drugs had a moderate incidence of side effects, including constipation (verapamil) and ankle swelling (nifedipine).
Conclusions:
- Calcium-entry blockers are suitable for initial hypertension therapy when standard drugs are contraindicated.
- Nifedipine is a preferable alternative to hydralazine in combination therapy with beta-blockers and diuretics due to comparable efficacy and fewer serious adverse effects.
Abstract:
Calcium-entry blocking agents resemble established dilators such as diazoxide, minoxidil and hydralazine in that they act predominantly on the arterial resistance vessels and have little or no effect upon the veins. They have therefore been evaluated in the treatment of hypertension. Controlled studies have shown that verapamil and nifedipine are effective in decreasing blood pressure when given as sole agents. The antihypertensive effect of nifedipine is additive with that of a beta blocker, and nifedipine is also effective when given as a "third step" agent in combination with a beta blocker (or alpha methyldopa) and a diuretic. In contrast to other directly acting dilators, nifedipine causes, at most, only moderate stimulation of renin secretion and verapamil does not increase renin release at all; neither drug induces sodium retention. Both verapamil and nifedipine produce a moderate incidence of unwanted effects; these are mostly subjective in nature, but verapamil may cause constipation that is occasionally severe and nifedipine sometimes causes ankle swelling. Calcium-entry blockers should be considered as initial therapy when some contraindication exists to the use of other standard drugs. Nifedipine appears preferable to hydralazine for use in combination with a beta blocker and a diuretic: it is at least as effective as hydralazine and has a lower incidence of serious adverse effects.