Diuretic agents and beta-blockers in the treatment of hypertension

Benzothiadiazine diuretic agents and beta-adrenergic receptor-blocking drugs are two of the main groups of drugs used to treat mild hypertension. Recently, questions have been raised about their relative efficacy in preventing morbidity and mortality from vascular disease in addition to their effect on lowering blood pressure. Attention has been focused on the unfavorable metabolic effects of diuretic drugs and the proven value of beta-adrenergic receptor blockade in secondary prevention after myocardial infarction. Four randomized controlled trials comparing drugs in these two classes have been published: the Medical Research Council trial, the International Prospective Primary Prevention Study in Hypertension, the Heart Attack Primary Prevention in Hypertension trial, and the Metoprolol Atherosclerosis Prevention in Hypertension study. These trials, especially that of the Medical Research Council, have raised some questions about the relative efficacy of these two classes of drugs in preventing stroke in smokers and nonsmokers. Overall, there is little evidence of a reduction in morbidity and mortality after myocardial infarction. The predicted advantage of beta-adrenergic receptor blockade over diuretic therapy has not been realized although there are sufficient hints of a differential benefit to encourage the performance of further trials.