Low-dose diuretic and beta adrenoceptor blocker in essential hypertension

Dose response to hydrochlorothiazide in hypertensives receiving a calcium channel blocker

Seven hypertensive patients receiving the dihydropyridine calcium channel blocking agent nicardipine were given placebo, 6.25, 12.5, 25 and 50 mg hydrochlorothiazide (HCTZ) in a randomized crossover design. Blood pressure (BP) decreased by about 7/3 mmHg irregardless of dose. In contrast, potassium, glucose and uric acid increased in a dose-dependent fashion. The hypokalemic and hyperglycemic responses at 50 mg were larger than usually seen with HCTZ. Low doses of HCTZ provided a modest antihypertensive effect, but 25 and 50 mg of HCTZ were no more effective in lowering BP and gave unusually large metabolic side effects when combined with a calcium channel blocker.

Demographic considerations in the selection of antihypertensive therapy

Because of the growing number of antihypertensive agents that are suitable for initial therapy in mild and moderate hypertension, it is important to identify factors that influence the response to various medications. Although individual patient considerations, such as associated illnesses and potential side effects, are of primary importance in choosing therapy, the influence of demographic factors has received increasing attention. The effect of age, race and gender on the response to antihypertensive therapy will be examined. Several studies have indicated that the beta blockers and angiotensin converting enzyme (ACE) inhibitors are more effective in younger than in older patients. Conversely, there is a trend toward greater responses in older subjects to the diuretics and calcium antagonists. In the few studies available that have compared agents in various classes, it appears that diuretics, and probably calcium antagonists, are significantly more effective than beta blockers or ACE inhibitors in patients over 60 years of age. However, the interdrug differences in young patients are probably less important. With regard to race, the relative lack of effect of beta blockers and ACE inhibitors in blacks is well accepted; in comparative studies, diuretics proved significantly better. From the few available studies, it does not appear that the calcium antagonists are more potent in either racial group, but they may be superior to the beta blockers and ACE inhibitors in blacks. Far less information is available concerning differences in antihypertensive responses between men and women. There is some suggestion that women may be less responsive to beta blockers than men.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of diuretic agents in obese or black patients with systemic hypertension

Any increase in arterial pressure is the result of either an increase in cardiac output, an increase in total peripheral resistance or a combination of the two. Hypertension is not a homogeneous disease, however, and different mechanisms may be operative during the life span of the patient. Hypertension in the young, nonobese patient is usually hemodynamically characterized by high cardiac output, normal to slightly contracted intravascular volume and numerically normal total peripheral resistance. In contrast, hypertension in the middle-aged or elderly patient is usually hemodynamically characterized by normal to low cardiac output, contracted intravascular volume and high total peripheral resistance. Two further subgroups of hypertensive patients can be identified: obese patients, whose hypertension is characterized by high cardiac output, expanded intravascular volume and normal or low total peripheral resistance, and black patients, whose hemodynamic and fluid volume findings are similar to those of their white counterparts, but who tend to have lower heart rates and greater responsiveness to intravascular volume depletion than white hypertensive subjects. A rational therapeutic approach to essential hypertension should take into account these variable pathophysiologic features. Thiazide diuretics continue to be appropriate and generally well-tolerated choices for initial antihypertensive therapy in obese or in black patients. Many obese patients or black patients, however, are likely to develop early left ventricular (LV) hypertrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of aldosterone in the response to treatment of primary hypertension

The role of the renin-aldosterone axis in mediating responses to antihypertensive treatment was examined in patients with essential hypertension treated with propranolol (n=50) or chlorthalidone (n=50). Control plasma renin activity tended to be predictive of the response to treatment: it correlated with the diastolic blood pressure changes produced by both the renin-lowering agent, propranolol (r=-.43, P less than 0.001), and the diuretic, chlorthalidone (r= .48, P less than 0.001). However, when patients were divided into responders (fall in diastolic blood pressure of greater than 10%) and non-responders, the treatment-induced changes in aldosterone excretion rate appeared to be more important than the changes in renin in determining outcome. During propranolol there was no difference between the renin changes in the responders (n=21) and the non-responders (n=29), but aldosterone fell significantly more (P less than 0.025) in the responders than in the non-responders. Similarly, renin changes during chlorthalidone were not markedly different between the two groups, but the increase in aldosterone excretion in the non-responders was significantly greater (P less than 0.001) than in the responders (n=25). Thus, regardless of the treatment used, responders were characterized by having lower levels of aldosterone during therapy than non-responders. This possible role for aldosterone in influencing blood pressure changes was not related to clinically measurable effects on fluid and electrolyte balance; it has been conjectured that this pressor effect of aldosterone could reflect a direct action in the peripheral circulation.

Effect of pindolol and propranolol on renal function of patients with hypertension

1 Pindolol and propranolol were administered orally in equipotent antihypertensive doses to 14 subjects with mild to moderate hypertension in an open cross-over study. 2 Pindolol caused a smaller decrease in plasma renin activity and heart rate than propranolol. 3 Glomerular filtration rate and effective renal plasma flow remained unchanged during therapy with either agent.