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Calcium blockade in arterial hypertension. Review
Insights
Calcium channel blockers effectively lower blood pressure in hypertension. While generally safe, nifedipine may require combination therapy due to tolerance, and long-term human benefits on cardiovascular structure need further study.
Area of Science:
- Pharmacology
- Cardiovascular Medicine
- Nephrology
Background:
- Arterial hypertension involves altered calcium (Ca++) roles in vascular smooth muscle.
- Calcium channel blockers exhibit enhanced vasodilatory effects in hypertensive individuals.
Purpose of the Study:
- To evaluate the efficacy and side effects of calcium channel blockers in managing arterial hypertension.
- To compare the acute and chronic effects of verapamil and nifedipine.
Main Methods:
- Acute and chronic administration of calcium channel blockers (verapamil, nifedipine).
- Monitoring of blood pressure, heart rate, plasma renin activity, and catecholamines.
- Assessment of diuretic, natriuretic, and uricosuric effects.
Main Results:
- Both verapamil and nifedipine reduce blood pressure acutely and chronically.
- Nifedipine causes more pronounced reflex increases in heart rate and catecholamines compared to verapamil.
- Acute diuretic, natriuretic, and uricosuric effects were observed.
- Tolerance to nifedipine develops with repeated administration, potentially requiring combination therapy.
Conclusions:
- Calcium channel blockers are effective antihypertensive agents.
- Nifedipine's long-term use may necessitate combination with other drugs like beta-blockers and diuretics.
- While animal studies show benefits on hypertensive cardiovascular changes, human data are still needed.
Abstract:
The use of calcium blockers in arterial hypertension is based on experimental evidence for an altered role of calcium (Ca++) in hypertensive vascular smooth muscle and enhanced vasodilatatory effects of these drugs in the hypertensive organism. Both verapamil and nifedipine reduce blood pressure acutely and on chronic administration. Acute administration results in reflex-activated increments of heart rate, plasma renin activity, and plasma catecholamines after nifedipine, whereas these effects are less conspicuous after verapamil. Acute diuretic, natriuretic, and uricosuric effects can be demonstrated. On repeated administration of nifedipine, a degree of tolerance develops and on long-term administration it may be necessary to combine it with a beta-adrenoceptor blocker and a diuretic. In animal experiments, calcium blockers have shown favorable effects on hypertensive cardiovascular structural changes, but such unique beneficial effects remain to be demonstrated in the human disease.