Doxazosin versus atenolol: a randomized comparison of calculated coronary heart disease risk reduction

Effects of antihypertensive drugs on coronary artery disease risk: a meta-analysis

1. The effects of antihypertensive drugs on lipids may also influence their effect on coronary artery disease (CAD). However, the clinical significance of these effects and the extent to which they persist during long-term therapy is uncertain. 2. We performed a meta-analysis on 23 randomized trials published between 1988 and 1994 that compared the effects of atenolol, celiprolol (a beta-blocker with beta 2-adrenoceptor intrinsic sympathomimetic activity), enalapril, nifedipine and doxazosin on plasma cholesterol, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), triglycerides and blood pressure (BP). 3. Predicted changes in CAD risk were calculated by incorporating the results for these parameters into the Framingham equations. 4. While there were no differences in antihypertensive efficacy between the drugs, atenolol significantly (P < 0.05) reduced HDL-C and increased total cholesterol, LDL-C and triglycerides compared with celiprolol, enalapril, doxazosin and nifedipine. 5. The magnitude of the effects on lipids was not significantly influenced by the duration of therapy (up to 3 years for atenolol and doxazosin and up to 2 years for celiprolol). 6. The improvement in Framingham equation point scores (systolic BP formula) was significantly (P < 0.05) less for atenolol (-0.54; confidence intervals (CI) -0.29-(-0.78)) than for celiprolol (-1.69; CI -0.68-2.70), doxazosin (-1.67; CI -1.11-(-2.23)), enalapril (-1.43; CI 0.23-(-3.07)) and nifedipine (-1.91; CI -1.22-(-2.59)). Similar results were obtained for the Framingham diastolic BP formula. 7. These results suggest that the adverse effects of atenolol ]on plasma lipids do not improve with prolonged therapy and are theoretically great enough to reduce its efficacy in reducing CAD by approximately two thirds compared with antihypertensive drugs that do not adversely affect plasma lipids. However it must be emphasized that these are theoretical effects. In order to determine the actual differences between these drugs on CAD end points, studies using these end points are required.

Lipids and lipoproteins during antihypertensive drug therapy. Comparison of doxazosin and atenolol in a randomized, double-blind trial: the Alpha Beta Canada Study

A randomized double-blind trial comparing the alpha-adrenergic blocker doxazosin and the beta-adrenergic blocker atenolol was completed by 131 patients with mild to moderate hypertension. Blood pressure and fasting blood lipids were determined at baseline and 4, 12, and 24 weeks of treatment. At entry, plasma lipids and lipoproteins were similar in those patients randomized to doxazosin or atenolol. After 24 weeks of treatment with atenolol, there were significant (P < .05) decreases in high-density lipoprotein cholesterol (HDL-C) and increases in triglycerides and very-low-density triglycerides (VLDL-T). In contrast, doxazosin was associated with significant (P < .05) increases in HDL-C and decreases in triglycerides and VLDL-T. There were no significant differences in HDL apolipoprotein (apo) A-I or low-density lipoprotein apoB between the drugs, but atenolol decreased the ratio of HDL-C to apoA-I, and doxazosin increased this ratio, differences that were statistically significant (P < .002). Neither apoA-I nor apoB concentration at baseline nor apoE phenotype was predictive of the lipid responses during antihypertensive treatment with either drug. Thus, there are significant favorable changes in HDL-C, total triglycerides, and VLDL-T between patients with mild to moderate hypertension and normal plasma lipids when treated with the alpha-blocker doxazosin compared with the beta-blocker atenolol. Plasma lipid or apo concentrations were not predictive of their lipid response during antihypertensive therapy with either of these agents.

Alpha 1 blockers. Safe, effective treatment for hypertension

Alpha 1-adrenergic blocking agents, used alone or in combination with other medications, are efficacious in the management of hypertension. They are safe and well tolerated, and they offer unique advantages. Their mechanism of action in lowering blood pressure targets elevated peripheral vascular resistance, which is the principal hemodynamic abnormality of essential hypertension. The alpha 1 blockers maintain cardiac output and blood flow to vital organs, and they do not affect renin release. These agents have beneficial lipid and metabolic effects and can improve left ventricular hypertrophy, theoretically having a positive impact on cardiovascular morbidity and mortality. The only drug interaction identified with the alpha 1 blockers is an increased hypotensive effect when they are combined with other antihypertensive agents. A further advantage of the alpha 1 blockers is that, because of the widespread location of alpha 1 receptors, the agents offer potential benefit for a number of disease states, including benign prostatic hyperplasia. They also provide an especially useful antihypertensive choice for middle-aged and elderly patients.

The addition of doxazosin to the treatment regimen of patients with hypertension not adequately controlled by beta-blockers

When doxazosin was given to patients with hypertension not adequately controlled by beta-blockade, blood pressure was normalized in 94% of the 34 patients (blood pressure less than or equal to 140/85 mm Hg). This reduction in blood pressure was obtained with doxazosin in combination with metoprolol or oxprenolol at a mean final daily dose of 1.3 mg or pindolol or atenolol at 2.0 mg/day. Exercise-induced increase in systolic and diastolic blood pressure was also lower with combined beta-blocker and doxazosin therapy than with beta-blocker alone. After 12 weeks of treatment, the combination of doxazosin and beta-blocker significantly reduced total serum cholesterol and triglyceride levels. All side effects were mild and only one patient was withdrawn from therapy.

A multicenter study of doxazosin in the treatment of patients with mild or moderate essential hypertension and concomitant intermittent claudication

This study assessed the efficacy and safety of once-daily doxazosin in the treatment of patients (n = 19) with mild or moderate essential hypertension (sitting diastolic blood pressure [DBP] 95 to 114 mm Hg) and concomitant intermittent claudication (Doppler ankle/arm ratio of less than 0.80 and walking tolerance of less than 700 m on the treadmill). After 14 weeks of treatment with doxazosin, a significant (p less than 0.05) reduction in systolic blood pressure and DBP was observed. Mean blood pressures were reduced from 170/100 mm Hg at baseline to 161/93 mm Hg at the end of treatment. Minor changes in heart rate occurred, which with continued treatment were not statistically significant from baseline. In 12 of 16 (75.0%) efficacy-evaluable patients blood pressure was normalized (DBP to less than or equal to 90 mm Hg with an greater than or equal to 5 mm Hg reduction from baseline) with a mean daily dose of 7.6 mg/day. Doxazosin improved the hypertension severity category in 13 of 16 (81.3%) patients. The blood pressure ratios between both the thighs and arms and ankles and arms showed no statistically significant changes after treatment with doxazosin. Thigh blood flow at rest and the reactive hyperemia after 3 minutes of arterial occlusion did not change statistically. There was a tendency for pain-free distance to improve. Laboratory data were not significantly changed after treatment with doxazosin. Of the 19 patients studied, 5 reported mild or moderate side effects that were either tolerated or disappeared with continued treatment. No patient had therapy withdrawn and no patient required a dose reduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy and safety of doxazosin in the treatment of patients with mild or moderate essential hypertension and elevated levels of cholesterol

In hypertensive patients, elevated serum cholesterol is a frequent and sinister additional coronary risk factor. Selective alpha 1-adrenoreceptor inhibitors appear to have the unique ability to control both risk factors. Forty-two patients, ages 42 to 65 years, including 21 men with sustained hypertension and elevated serum cholesterol levels, were included in a trial of monotherapy with doxazosin administered once daily (range, 1 to 16 mg). The influence of the drug on high blood pressure and elevated serum cholesterol was evaluated over a 28-week period, which consisted of a 4-week, single-blind placebo lead-in period, an open 10-week dose-adjustment period, and finally a 14-week maintenance period. Of the 39 efficacy-evaluable patients, 25 (64%) achieved adequate blood pressure control (diastolic blood pressure less than 90 mm Hg or a decrease in diastolic blood pressure greater than 10 mm Hg) at a mean daily dose of 2 mg of doxazosin. No persistent changes occurred in heart rate. In the 32 patients with evaluable lipid data, there were nonsignificant trends to an increase in high-density lipoprotein cholesterol and a reduction in total cholesterol, together with a significant reduction in serum triglyceride concentration. The combined changes in blood pressure and blood lipid levels resulted in a reduction of 36% in the calculated risk of coronary heart disease. Eleven patients reported side effects and four were withdrawn from therapy. These results confirm the antihypertensive and anticholesterolemic efficacy of once-daily treatment with doxazosin.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical pharmacotherapeutics of doxazosin

Doxazosin is the latest in a series of highly selective postsynaptic alpha 1-adrenoceptor inhibitors. It is readily absorbed, with high bioavailability and a relatively long plasma half-life, neither of which property is influenced by age. This accounts for the prolonged pharmacologic activity of doxazosin following a single oral dose. Its prime pharmacodynamic activity resides in its ability to counter sympathetic vasoconstriction of the systemic arteriolar resistance vessels and venous capacitance system, which enables the drug to target the major pathophysiologic abnormality in hypertension, i.e., the generalized systemic arteriolar constriction. The widespread vasodilation induced by doxazosin relieves both cardiac preload and afterload and, consequently, reduces left ventricular wall stress and myocardial oxygen consumption. In hypertension, doxazosin reduces blood pressure both at rest and during exercise by reduction of systemic vascular resistance without precipitating substantial reflex cardiac stimulation. The effects are maximal on the standing blood pressure between two and four hours after ingestion; due to doxazosin's relatively slow absorption, postural hypotension is infrequent. Its antihypertensive activity is maintained over 24 hours following a single oral dose, and the optimal dose range is 2 to 8 mg once daily. The antihypertensive efficacy of doxazosin has been shown to be comparable with that of other alpha-adrenoceptor inhibitors, beta-blocking drugs, diuretics, calcium antagonists, and angiotensin-converting enzyme inhibitors. In contrast to other conventional antihypertensive drugs, a unique feature of alpha-adrenoceptor-inhibiting drugs, including doxazosin, is their ability to reduce the plasma concentrations of triglycerides, total cholesterol, and low-density lipoprotein cholesterol and to increase high-density lipoprotein cholesterol concentration. This contrasts with the opposite effect on lipid levels induced by hydrochlorothiazide and atenolol seen in comparative studies. Side effects show no predilection for any organ system, and the overall incidence of such effects compares well with those of other commonly used antihypertensive drugs. This unique combination of antihypertensive efficacy and favorable effect on blood lipid levels indicates that once-daily treatment with doxazosin holds considerable promise in the treatment of hypertension, both from the point of view of its antihypertensive efficacy and also from its primary preventative potential.