COMPARISON OF THE HEMODYNAMIC-EFFECTS OF METOPROLOL AND CARVEDILOL INHYPERTENSIVE PATIENTS

Metoprolol and carvedilol are widely used in the treatment of hyperten sion, but no randomized comparison of their hemodynamic activity has b een previously reported. Their comparative effects on heart rate, syst emic blood pressure, and echocardiographically determined aortic and f emoral artery blood flow were measured at rest and at 2 and 24 hours a fter the first dose of each drug, and again after 4 weeks of sustained monotherapy in 12 male and 12 female patients, aged 36-68 years with uncomplicated sustained hypertension according to a randomized single- blind protocol. Nine patients in each drug group achieved the target d iastolic blood pressure of <90 mmHg on the initial doses of each drug; this was achieved in the remainder following doubling of each dose. N either drug occasioned withdrawal of any patient due to adverse reacti ons. Both drugs significantly reduced heart rate, although the reducti on at 2 hours was significantly greater after metoprolol than after ca rvedilol. Both drugs reducd systolic pressure throughout the study; th e reduction at 2 hours was significantly greater after carvedilol than after metoprolol. In contrast, the diastolic blood pressure was persi stently reduced only by carvedilol. The cardiac output, determined as the aortic systolic blood flow, after carvedilol was not significantly different from pretreatment values throughout the study but was signi ficantly reduced in the metoprolol-treated patients at each point of m easurement. After metoprolol the systemic and femoral vascular resista nces derived from conventional formulae were consistently and signific antly increased over pretreatment values throughout the study and were significantly greater than in the carvedilol group at all measurement points. The hemodynamic differences between these two beta-blocking d rugs may be explained by the additional vasodilator activity of carved ilol associated with its alpha(1)-adrenoceptor blocking activity. The long-term clinical and prognostic implications of these pharmacodynami c differences between beta-adrenoceptor antagonists with and without a dditional vasodilator activity in the treatment of hypertensive patien ts remain to be determined.