Multicentre 12-week double-blind comparison of doxazosin, prazosin and placebo in patients with mild to moderate essential hypertension

Adreno-melatonin receptor complexes control ion homeostasis and intraocular pressure - their disruption contributes to hypertensive glaucoma

BACKGROUND AND PURPOSE

Often, glaucoma presents with elevated eye hydrostatic pressure, which is regulated by endogenous melatonin. Phenylephrine increases cytoplasmic [Ca²⁺ ], via α₁ -adrenoceptor activation, that is detrimental in glaucoma. The aims of this study were (a) to elucidate the role of melatonin receptors in humour production and intraocular pressure (IOP) maintenance and (b) to identify glaucoma-relevant melatonin-adrenoceptor interactions.

EXPERIMENTAL APPROACH

Biophysical and proximity ligation assays were performed to identify interactions in heterologous expression systems, in cell lines and in human eyes. G_s /G_i /G_q signalling was investigated in these systems and in cells producing aqueous humour. IOP was determined in a mice model of glaucoma. Retinography and topically pharmacological treatment were performed in control and in glaucomatous mice.

KEY RESULTS

α₁ -adreno- and melatonin receptors form functional complexes in which the C-terminal tail of the adrenoceptor plays a role. Remarkably, activation of α₁ -adrenoceptors in these complexes did not lead to cytosolic Ca²⁺ increases, suggesting G_s instead of G_q coupling is involved. The number of these complexes significantly decreased in models of glaucoma and, importantly, in human samples from glaucoma patients. This has led to hypothesize that melatonin, a hypotensive agent, plus blockade of α₁ -adrenoceptors could normalize pressure in glaucoma. Remarkably, co-instillation of melatonin and prazosin, an α₁ -adrenoceptor antagonist, resulted in long-term decreases in IOP in a well-established animal model of glaucoma.

CONCLUSIONS AND IMPLICATIONS

The findings are instrumental to understand the physiological function of melatonin in the eye and its potential to address eye pathologies by targeting melatonin receptors and their complexes.

Direct Vasodilators and Sympatholytic Agents

Direct vasodilators and sympatholytic agents were some of the first antihypertensive medications discovered and utilized in the past century. However, side effect profiles and the advent of newer antihypertensive drug classes have reduced the use of these agents in recent decades. Outcome data and large randomized trials supporting the efficacy of these medications are limited; however, in general the blood pressure-lowering effect of these agents has repeatedly been shown to be comparable to other more contemporary drug classes. Nevertheless, a landmark hypertension trial found a negative outcome with a doxazosin-based regimen compared to a chlorthalidone-based regimen, leading to the removal of α-1 adrenergic receptor blockers as first-line monotherapy from the hypertension guidelines. In contemporary practice, direct vasodilators and sympatholytic agents, particularly hydralazine and clonidine, are often utilized in refractory hypertension. Hydralazine and minoxidil may also be useful alternatives for patients with renal dysfunction, and both hydralazine and methyldopa are considered first line for the treatment of hypertension in pregnancy. Hydralazine has also found widespread use for the treatment of systolic heart failure in combination with isosorbide dinitrate (ISDN). The data to support use of this combination in African Americans with heart failure are particularly robust. Hydralazine with ISDN may also serve as an alternative for patients with an intolerance to angiotensin antagonists. Given these niche indications, vasodilators and sympatholytics are still useful in clinical practice; therefore, it is prudent to understand the existing data regarding efficacy and the safe use of these medications.

Blood pressure lowering efficacy of alpha blockers for primary hypertension

BACKGROUND

Alpha blockers are occasionally prescribed for hypertension so it is important to determine and compare their effects on blood pressure (BP), heart rate and withdrawals due to adverse effects (WDAE).

OBJECTIVES

To quantify the dose-related systolic and/or diastolic BP lowering efficacy of alpha blockers versus placebo in the treatment of primary hypertension.

SEARCH METHODS

For the updated review, we searched CENTRAL (The Cochrane Library 2012, Issue 4), MEDLINE (1946 to May 2012), EMBASE (1980 to May 2012) and reference lists of articles.

SELECTION CRITERIA

Double-blind, randomized, controlled trials evaluating the BP lowering efficacy of fixed-dose monotherapy with an alpha blocker compared with placebo for a duration of 3 to 12 weeks in patients with primary hypertension.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias and extracted data. Study authors were contacted for additional information. WDAE information was collected from the trials.

MAIN RESULTS

Only 10 trials evaluated the dose-related trough BP lowering efficacy of 4 different alpha blockers in 1175 participants with a baseline BP of 155/101 mm Hg. The data do not suggest that any one alpha blocker is better or worse at lowering BP. The best but unsatisfactory estimate of the trough BP lowering efficacy for alpha blockers is -8/-5 mmHg.

AUTHORS' CONCLUSIONS

Based on the limited number of published RCTs, the BP lowering effect of alpha blockers is modest; the estimate of the magnitude of trough BP lowering of -8/-5 mmHg is likely an overestimate. There are no clinically meaningful BP lowering differences between different alpha blockers. The review did not provide a good estimate of the incidence of harms associated with alpha blockers because of the short duration of the trials and the lack of reporting of adverse effects in many of the trials.

Blood pressure lowering efficacy of alpha blockers for primary hypertension

BACKGROUND

Alpha blockers are occasionally prescribed for hypertension so it is important to determine and compare their effects on blood pressure (BP), heart rate and withdrawals due to adverse effects (WDAE).

OBJECTIVES

To quantify the dose-related systolic and/or diastolic BP lowering efficacy of alpha blockers versus placebo in the treatment of primary hypertension.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library 2009, Issue 1), MEDLINE (1950 to April 2009), EMBASE (1980 to April 2009) and reference lists of articles.

SELECTION CRITERIA

Double-blind, randomized, controlled trials evaluating the BP lowering efficacy of fixed-dose monotherapy with an alpha blocker compared with placebo for a duration of 3 to 12 weeks in patients with primary hypertension.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias and extracted data. Study authors were contacted for additional information. WDAE information was collected from the trials.

MAIN RESULTS

Only 10 trials evaluated the dose-related trough BP lowering efficacy of 4 different alpha blockers in 1175 participants with a baseline BP of 155/101 mm Hg. The data do not suggest that any one alpha blocker is better or worse at lowering BP. The best but unsatisfactory estimate of the trough BP lowering efficacy for alpha blockers is -8/-5 mmHg.

AUTHORS' CONCLUSIONS

Based on the limited number of published RCTs, the BP lowering effect of alpha blockers is modest; the estimate of the magnitude of trough BP lowering of -8/-5 mmHg is likely an overestimate. There are no clinically meaningful BP lowering differences between different alpha blockers. The review did not provide a good estimate of the incidence of harms associated with alpha blockers because of the short duration of the trials and the lack of reporting of adverse effects in many of the trials.

Impact of alpha 1-adrenergic antagonist use for benign prostatic hypertrophy on outcomes in patients with heart failure

Previous clinical trials have shown that alpha(1)-adrenergic antagonists are not effective in subjects with heart failure (HF) and might increase HF rates when used for hypertension. However, alpha(1)-adrenergic antagonists may be prescribed to subjects with HF who have symptomatic benign prostatic hyperplasia. We sought to determine any association between alpha(1)-adrenergic antagonist use, commonly prescribed for benign prostatic hyperplasia, and the clinical outcomes of subjects with HF receiving contemporary therapy. An existing database of 388 subjects with decompensated HF admissions from 2002 to 2004 at the Veterans Affairs Hospital was analyzed according to the use of alpha(1)-adrenergic antagonists at discharge. Covariate-adjusted Cox proportional hazard models were used to examine any association with future admissions for decompensated HF and total mortality. Alpha-1-adrenergic antagonist therapy was prescribed in 25% of our HF population, predominantly for benign prostatic hyperplasia, and was not associated with significant increases in the combined risk of all-cause mortality and rehospitalization for HF (hazard ratio 1.24, 95% confidence interval 0.93 to 1.65, p = 0.14), HF hospitalization (hazard ratio 1.20, 95% confidence interval 0.85 to 1.70, p = 0.31), or all-cause mortality (hazard ratio 1.10, 95% confidence interval 0.78 to 1.56, p = 0.57). In patients not receiving beta-blocker therapy, alpha(1)-adrenergic antagonist therapy was significantly associated with increased HF hospitalizations (hazard ratio 1.94, 95% confidence interval 1.14 to 3.32, p = 0.015). In conclusion, in patients with chronic HF, the use of alpha(1)-adrenergic antagonists was significantly associated with more HF hospitalizations when prescribed without concomitant beta blockade. Thus, background beta-blocker therapy appears to be protective against the potential harmful effects of alpha(1)-adrenergic antagonist therapy in patients with HF.

A 24-week multicenter double-blind study of doxazosin and hydrochlorothiazide in patients with mild to moderate essential hypertension

The new alpha1-adrenoceptor antagonist, doxazosin (DOX), was compared with hydrochlorothiazide (HCTZ), both drugs administered once daily, in a randomized double-blind study including 115 patients. The mean final daily doses used were DOX, 10.8 mg; HCTZ, 89.1 mg. There were no statistically significant differences between treatment groups for blood pressure (BP) changes except that HCTZ produced a significantly greater fall (p = 0.04) in supine systolic BP than DOX. The statistically significant mean differences in changes in lipid parameters (total cholesterol and total triglycerides) were in favour of DOX. The number of patients reporting side-effects were DOX, 27/57; HCTZ, 29/53, with two DOX- and five HCTZ-treated patients withdrawn due to side-effects. In the HCTZ-treated group, laboratory serum tests indicated 11 patients with abnormally low potassium and seven with abnormally high uric acid concentrations. The overall results suggest a benefit-to-risk ratio in favour of DOX.

A Review of the Adverse Effects of Peripheral Alpha-1 Antagonists in Hypertension Therapy

BACKGROUND: Doxazosin and its role as an antihypertensive agent have come under recent scrutiny as a result of the early termination of that treatment arm in ALLHAT. It is unclear why the cardiovascular (CV) event rate in this randomized, controlled trial (RCT), especially heart failure, is higher in those treated with a doxazosin-based regimen than with a chlorthalidone based-regimen. There has been little work in the past to summarize information on peripheral alpha-1 antagonists that may be helpful in evaluating the results of this randomized controlled trial. METHODS: Using Medline and the Cochrane databases, we performed a comprehensive review of the literature on the use of peripheral alpha-1 antagonists as antihypertensive agents, focusing on available information that could explain the excess cardiovascular events observed in the Antihypertensive and Lipid-Lowering Treatment to prevent Heart Attack Trial (ALLHAT). RESULTS: Minimal data were available concerning the effects of peripheral alpha-1 antagonists on CV endpoints. A multitude of short-term studies-ranging from small observational studies to short-term moderate-sized RCTs - focused on safety, efficacy, and tolerability, and some studies investigated the physiologic effects of these agents. These previously reported studies reveal associations with weight gain, fluid retention, and neurohormonal changes among various populations of those treated with peripheral alpha-1 antagonists. CONCLUSION: These findings suggest several possible mechanisms by which doxazosin may be inferior to low-dose diuretics as antihypertensive therapy for the prevention of heart failure.

Effects of doxazosin on functional alterations of isolated coronary arteries from cholesterol-fed rabbits

Anti-hypertensive treatment is much less successful at reducing coronary artery disease than at reducing mortality from stroke and congestive heart failure. The effects of the alpha-adrenergic antagonist doxazosin on progression of atheromatous lesions and functional responses of isolated coronary arteries from cholesterol-fed rabbits have been investigated. Normotensive rabbits were fed either a standard chow (control, n = 8) or a 1% cholesterol-rich diet (n = 16) for 20 weeks. After 3 weeks the cholesterol-fed animals were assigned randomly to two groups either given placebo capsules (n = 8) or treated with doxazosin (5 mg kg-1 day-1; n = 8). Doxazosin reduced the mean arterial blood pressure by 10% that of the control and placebo-treated cholesterol-fed rabbits, but did not affect the plasma cholesterol, triacylglycerol and phospholipid levels, which were, after 20 weeks, severalfold increased in the cholesterol-fed rabbits compared with controls. Histological examination showed atheromatous lesions in proximal (but not distal) coronary arteries from both groups of cholesterol-fed rabbits. Doxazosin either had no effect on reduced contractions to 125 mmol L-1 potassium saline solution or increased contractions to 5-hydroxytryptamine in proximal isolated coronary arteries from the cholesterol-fed rabbits. It did, however, abolish the hyper-responsiveness of the large atheromatous coronary arteries to noradrenaline. In both vehicle-and doxazosin-treated cholesterol-fed rabbits the maximum relaxation and sensitivity to acetylcholine were significantly reduced in proximal segments compared with the control group, whereas responses to acetylcholine in distal coronary segments were not significantly different. The relaxation to sodium nitroprusside, adenosine diphosphate and isoprenaline in proximal and distal coronary arteries were similar in the three experimental groups. These results indicate that treatment of normotensive cholesterol-fed rabbits with doxazosin prevents the hyper-responsiveness to noradrenaline of proximal coronary arteries, although it does not prevent the progression of other functional alterations observed in the coronary circulation.

Doxazosin. An update of its clinical pharmacology and therapeutic applications in hypertension and benign prostatic hyperplasia

Doxazosin is a long-acting alpha 1-adrenoceptor antagonist structurally related to prazosin and terazosin. Its antihypertensive effect is produced by a reduction in the smooth muscle tone of peripheral vascular beds resulting in a decrease in total peripheral resistance without significant effect on cardiac output or heart rate. In benign prostatic hyperplasia, doxazosin's effect of relieving bladder outflow obstruction is produced through a reduction in prostatic tone mediated via alpha 1-adrenoceptor blockade. In most comparative trials doxazosin has proven to be equally effective as the comparator drug in the treatment of mild to moderate hypertension. It has been used in a variety of patient populations including the elderly, Blacks, smokers, and patients with concomitant disease states such as renal dysfunction, hypercholesterolaemia, non-insulin dependent diabetes mellitus (NIDDM) and respiratory disease. Doxazosin has also been used successfully in combination with beta-adrenoceptor antagonists, diuretics, calcium channel antagonists, and angiotensin-converting enzyme inhibitors in patients with hypertension that is uncontrolled with monotherapy. Doxazosin has a beneficial effect on some of the risk factors associated with coronary heart disease including elevated serum lipid levels, impaired glucose metabolism, insulin resistance and left ventricular hypertrophy. Modest decreases in total cholesterol, low density lipoprotein cholesterol and triglycerides are seen with doxazosin therapy while small increases in high density lipoprotein cholesterol and the high density lipoprotein cholesterol/total cholesterol ratio are consistently reported. Some studies have reported an improvement in glucose tolerance although this effect has been more consistently seen in nondiabetic patients than in patients with NIDDM. Additionally, doxazosin produces a similar reduction in left ventricular hypertrophy to other antihypertensive agents. Modelling-based calculations suggest that doxazosin significantly reduces the risk of developing coronary heart disease in patients with mild to moderate hypertension, although this remains to be confirmed in long term prospective studies. Doxazosin appears to be a promising agent in the treatment of urinary symptoms associated with benign prostatic hyperplasia. Similar to other alpha 1-adrenoceptor antagonists, doxazosin treatment produces increases in peak and mean urinary flow rates and improves other objective and symptomatic measures.(ABSTRACT TRUNCATED AT 400 WORDS)

Antihypertensive therapy

Choosing antihypertensive agents that protect patients against cardiovascular and other complications is a growing trend in the treatment of mild to moderate hypertension. Calcium channel blockers and angiotensin-converting enzyme (ACE) inhibitors are favored because they have neutral or positive effects on lipid levels and insulin resistance. The alpha 1 blockers, especially doxazosin mesylate (Cardura), are enjoying a resurgence in popularity because they have a beneficial effect on lipid levels. In terms of preserving patients' quality of life, the ACE inhibitors in particular have been shown to have a positive impact. It has been shown that systolic hypertension in elderly patients should definitely be treated, but the most appropriate agent has yet to be defined. Therapy should be tailored to the individual. The following questions should be considered when choosing an antihypertensive agent: (1) What are its side effects (especially metabolic ones)? (2) Does it require only once- or twice-a-day dosing? (3) Does it cause regression of left ventricular hypertrophy? (4) Does it prevent death from coronary artery disease? (5) How will it affect quality of life? (6) How much does it cost? The goal of therapy should be to provide adequate blood pressure control throughout the day, enhance compliance, and protect the heart, brain, and kidneys without adversely affecting metabolic state.

Doxazosin effects on insulin and glucose in hypertensive patients. The Finnish Multicenter Study Group

This study investigates the effects of prolonged doxazosin treatment on serum lipids, glucose, serum insulin, and blood pressure in hypertensive patients. Following 26 weeks of treatment with doxazosin, supine and standing blood pressures were significantly decreased at a final mean daily dose of 6.4 mg. Blood glucose levels were significantly lower at 26 weeks than after the initial placebo period (p less than 0.05) or after 4 weeks' treatment with doxazosin (p less than 0.001). There was a significant (p less than 0.05) decrease in serum insulin levels following 4 weeks of treatment, and a highly significant (p less than 0.001) decrease after 26 weeks. In addition, doxazosin produced a significant reduction in total cholesterol (p less than 0.05) and low-density lipoprotein (LDL) cholesterol (p less than 0.01) after 26 weeks, although the levels of high-density lipoprotein (HDL) cholesterol, very-low-density lipoprotein (VLDL) cholesterol, and triglycerides showed no significant change. There was a tendency for the ratio of HDL: total cholesterol to increase. The combined changes in blood pressure, blood glucose levels, serum insulin, and serum lipids favorably affect the probability of developing coronary heart disease (CHD).

Newer antihypertensive agents

Three recent additions to the list of antihypertensive agents have been approved for use as monotherapy or in combination with other drugs. Betaxolol hydrochloride (Kerlone) maintains its effect for 24 hours, making it a true once-a-day beta blocker. Penbutolol sulfate (Levatol) is as effective as other beta blockers and diuretics. Doxazosin mesylate (Cardura), a selective alpha 1 blocker, also allows once-a-day dosing and has produced favorable changes in lipid profiles. Two new drug delivery systems, one for verapamil hydrochloride (Verelan) and one for extended-release nifedipine (Procardia XL), allow less frequent dosing and may offer other advantages, such as greater compliance and a more tolerable side-effect profile.

Effects of celiprolol and other antihypertensive agents on serum lipids and lipoproteins

The expected reduction in coronary heart disease morbidity and mortality has not been observed in intervention trials with antihypertensive agents, and attention has focused on the lipid and lipoprotein effects of antihypertensive agents. Diuretics, especially thiazides, chlorthalidone, and the loop diuretics, increase total and low-density lipoprotein cholesterol and triglyceride levels with generally no significant change in high-density lipoprotein cholesterol. Selective and nonselective beta-blockers decrease high-density lipoprotein cholesterol and increase triglyceride levels, whereas those with intrinsic sympathomimetic activity do not significantly alter lipid and lipoprotein levels. Celiprolol, a beta-blocker with vasodilatory effects, appears to favorably affect lipid and lipoprotein levels as do the alpha 1-adrenergic blockers. The other commonly used antihypertensive agents do not produce significant effects.

Doxazosin in the treatment of essential hypertension in general medical practice in Latin America

This Latin American study assessed in the general practice setting the efficacy and tolerance of once-daily doxazosin in the treatment of mild or moderate essential hypertension (sitting diastolic blood pressure, 95 to 115 mm Hg). Patients (n = 220) were treated with doxazosin for 12 weeks as monotherapy or in combination with other antihypertensive agents. At the final visit, doxazosin produced a mean change in sitting systolic/diastolic blood pressure of -18.4/-14.4 mm Hg, at a mean daily dose of 4.3 mg. One hundred sixty-three (77.6%) of the 210 evaluable patients were considered a therapeutic success. Lipid analyses identified a statistically significant (p = 0.02) reduction in total serum cholesterol (4.85%) and an overall decrease in triglyceride levels (5.12%). According to the Framingham Heart Study equation, doxazosin produced a highly significant (p less than 0.001) 20% reduction in the calculated probability of developing coronary heart disease in 10 years. Of the 220 patients evaluated, 54 (24.5%) reported side effects that were considered related to treatment. Ten (4.5%) patients reported side effects unrelated to treatment and 37 (16.8%) reported events of unknown relationship. Most side effects were mild or moderate and were tolerated or disappeared with continued treatment. Nine patients (4.1%) were discontinued from therapy and in 13 (5.9%) the dose was reduced. The most prevalent side effects were headache and dizziness. The investigator's overall assessment of antihypertensive efficacy was excellent or good for 176 patients (80.4%); tolerance was considered excellent or good in 193 patients (88.5%).(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Clinical experience with doxazosin in general medical practice in The Netherlands

This study was designed to investigate the efficacy and toleration of once-daily doxazosin in the treatment of essential hypertension (sitting diastolic blood pressure 95 to 115 mm Hg) in a general medical practice. Fifty-three patients with mild or moderate essential hypertension entered a study of 14 weeks' duration. This consisted of a baseline run-in period of 2 weeks, a dose-adjustment phase with doxazosin (8 weeks), and a maintenance phase of 4 weeks. Doxazosin was initiated at 1 mg/day, and every 2 weeks the dose was doubled unless blood pressure was normalized (sitting diastolic blood pressure less than or equal to 90 mm Hg with greater than or equal to 5 mm Hg reduction from baseline) or significant side effects emerged. The maximum daily dose administered was 8 mg. Doxazosin produced a significant (p less than 0.05) final mean change in sitting blood pressure of -17.4/-12.2 mm Hg at a final mean daily dose of 4.1 mg. Heart rate was not significantly altered. A nonsignificant decrease in total cholesterol concentration (-2.66%, p = 0.06) and triglycerides (-8.80%, p = 0.09) was also observed. The effect of doxazosin on blood pressure and serum cholesterol resulted in a significant (p less than 0.001) reduction of 19% in calculated risk of coronary heart disease. The investigators' assessment of patient toleration of doxazosin was excellent or good in 86.8% of patients.

Effects of doxazosin on serum lipids: a review of the clinical data and molecular basis for altered lipid metabolism

The goal of antihypertensive treatment must be not only the reduction of high blood pressure, but also the effective management of elevated cholesterol levels and other risk factors of coronary heart disease (CHD). In controlled clinical trials, doxazosin has been shown to have antihypertensive efficacy comparable with other classes of antihypertensive agents and to lower the levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides while increasing the levels of high-density lipoprotein cholesterol. Doxazosin appears to inhibit the development of CHD on two fronts. First, doxazosin binds to the alpha 1-adrenoreceptor and inhibits the receptor-mediated responses to epinephrine and norepinephrine. Second, doxazosin has direct and indirect effects on lipid metabolism by increasing LDL receptor activity, decreasing intracellular LDL synthesis, reducing the synthesis and secretion of very low-density lipoprotein cholesterol, and stimulating lipoprotein lipase activity. Doxazosin may also inhibit platelet aggregation. Long-term studies will determine how these actions translate into reductions in the morbidity and mortality rates of CHD. First-year results from the Treatment of Mild Hypertension Study (TOMHS) have demonstrated expected reductions in blood pressure for all antihypertensive agents studied. The lipid changes have varied with the type of antihypertensive treatment and have been favorable for doxazosin.

Preliminary results of the Norwegian doxazosin postmarketing surveillance study: a twelve-week experience

The study was designed to investigate the safety and efficacy of doxazosin in the control of blood pressure in general medical practice; the results presented concern the first 748 patients evaluated over a 12-week period. Blood pressure was significantly reduced after treatment with doxazosin (-13/-9 mm Hg), and heart rate was not significantly altered. In addition, doxazosin significantly reduced total cholesterol levels (-6.7%), reduced triglyceride levels (-19.8%), increased high-density lipoprotein cholesterol levels (+2.5%), and the high-density lipoprotein:total cholesterol ratio (+9.7%). The calculated risk of coronary heart disease was reduced by 20.5% over a 12-week period. Thirty-five percent of patients reported at least one side effect, and the number of patients experiencing severe adverse reactions was small. Twenty patients (2.7%) discontinued treatment because of adverse events, and 2.7% had the dose of doxazosin reduced.

Double-blind comparison of doxazosin and enalapril in patients with mild or moderate essential hypertension

The antihypertensive efficacy and safety of doxazosin and enalapril were compared in the general practice setting (n = 54). Both agents produced comparable, statistically significant (p less than 0.05) reductions in mean blood pressure with no clinically relevant changes in heart rate. Side effects in the two groups were mild or moderate and disappeared or were tolerated with continued treatment. Doxazosin, in contrast to enalapril, produced a significant (p less than 0.05) reduction in the total serum cholesterol concentration, a reduction in the level of triglycerides, and a favorable increase in the high-density lipoprotein/total cholesterol ratio. The reduction in calculated coronary heart disease risk produced by doxazosin (-27.58%) was highly significant (p less than 0.0002) and greater than that produced by enalapril (-18.49% p less than 0.02).

Evidence of an antiplatelet aggregation action of doxazosin in patients with hypertension: an ex vivo study

Eighteen patients with a mean age of 54.7 years were included in the study. All patients had a diagnosis of mild or moderate essential hypertension (sitting diastolic blood pressure of 96 to 114 mm Hg). The study design was single blind and in two phases: phase I, placebo (4 weeks), and phase II, the active treatment (8 weeks) with increasing doses, if needed, of doxazosin every 2 weeks (1, 2, 4, and 8 mg/day). Results show that doxazosin has an antihypertensive effect that is dose dependent. Systolic, diastolic, and mean blood pressures were decreased significantly, and no effect on heart rate was observed. Doxazosin significantly inhibited the platelet aggregation induced by epinephrine, adenosine diphosphate, and collagen in a dose-dependent manner. In addition, treatment with doxazosin lowered total serum cholesterol and triglyceride levels, without changing other standard biochemical parameters. This indicates that doxazosin could offer a distinct therapeutic advantage in the modulation of atherogenic and thromboembolic factors associated with coronary heart disease.

The response of the light reflex of retinal vessels to reduced blood pressure in hypertensive patients

The response of retinal arteries and veins to 3 months of antihypertensive medication was studied in 10 patients (39-56 years old) with essential hypertension. We used computerized microdensitometry on fundus photographs, a technique allowing for objective and simultaneous measures of the caliber of blood columns and the width and intensity of their central 'light reflex'. A moderate lowering of diastolic and systolic blood pressures (P less than 0.001) resulted in a significant reduction in the intensity of reflection from retinal arteries (38.6%; P less than 0.005). An increase in the width of the blood column (2.8%; n.s.) and the reflex (8.6%; n.s.) was indicated. Traditionally, changes in light reflectivity has been associated with arteriosclerosis of the vessel wall. The study shows, however, that the vascular reflex is most sensitive to changes in the systemic blood pressure. This signals a need for critical reviewal of interpretation and usefulness of classical grading systems of ophthalmoscopic signs of hypertensive retinopathy.

Review of the effects of doxazosin, a new selective alpha 1-adrenergic inhibitor, on lipoproteins in patients with essential hypertension

Control of high blood pressure has failed to reduce the risk of atherosclerotic coronary heart disease (CHD). Hypercholesterolemia, which is common among hypertensive patients, cigarette smoking, and hypertension are the major risk factors for CHD. To minimize CHD risk, elevated blood pressure and atherogenic lipid levels should be lowered, but various antihypertensive agents appear to adversely affect lipid levels, actually precluding the CHD risk reduction expected from blood pressure control. Doxazosin, a once-daily, long-acting, alpha 1-adrenergic inhibitor, not only is effective therapy for essential hypertension but also has a favorable impact on lipids. During controlled studies of doxazosin's antihypertensive efficacy, the following blood lipid levels were measured: total cholesterol, total triglycerides, high-density lipoprotein (HDL) cholesterol (including HDL2 and HDL3), low-density lipoprotein (LDL) cholesterol, very low-density lipoprotein cholesterol, and apoproteins (apos) AI and B. Results showed total cholesterol (-0.8 to -8.9 percent), total triglycerides (-5.0 to -17.4 percent), and LDL (-9.0 to -16.9 percent) were reduced. The positive prognostic indicators, HDL (+0.7 to +13.0 percent) and HDL:total cholesterol ratio (+3.1 to +26.3 percent), were increased. Apo B decreased, but apo AI remained unchanged. In these hypertension studies, doxazosin has favorably reduced two major CHD risk factors. As part of a new, long-term, controlled, multicenter trial, the prospective benefits of these risk factor reductions on CHD morbidity and mortality will be quantified for doxazosin and other antihypertensive agents.

Effectiveness of doxazosin in systemic hypertension

Most alpha-receptor blocking drugs require divided daily administration because of a short plasma half-life. This multicenter study examined the effectiveness and safety of once-daily administration with doxazosin, a quinazoline analog alpha 1-receptor blocking drug with a plasma half-life of 19 hours. Patients with diastolic blood pressure (BP) of 90 to 115 mm Hg entered 4 weeks of single-blind placebo therapy and then were randomized to double-blind treatment with doxazosin (63 patients) or placebo (67 patients). After 10 weeks of titration, standing arterial BP was lowered by 14/11 mm Hg with doxazosin and by 0.5/0.9 mm Hg with placebo (p less than 0.001). Measured hourly for 12 hours after the dose, all standing and supine arterial BP values were significantly lower in the doxazosin group at each hour. Pulse rate increased slightly in both groups int he double-blind phase, but the increase with doxazosin never significantly exceeded that of placebo. Dizziness was the most common complaint with doxazosin, but syncope did not occur. Side effects were mild and transient and did not necessitate withdrawing any participants from the study. Body weight increased by 1.5 kg in the doxazosin group and decreased by 0.2 kg in the placebo group (p less than 0.01). Safe and effective in once-daily administration, doxazosin is suitable for initial therapy in mild and moderate hypertension.

The relevance of plasma lipid changes with cardiovascular drug therapy

Evidence is reviewed that thiazide diuretics increase plasma levels of triglycerides and LDL-cholesterol, and that most beta-blockers increase triglycerides and depress HDL-cholesterol. By contrast, indapamide, pindolol, and calcium channel blockers have little effect, and alpha 1-blockers and alpha 2-stimulants may improve the HDL- to LDL-cholesterol ratio.

Alpha-1 adrenoceptor blockade with doxazosin in hypertension: effects on blood pressure and lipoproteins

The effects of doxazosin, a long-acting alpha-1 adrenoreceptor blocking drug, were observed upon blood pressure and serum lipoproteins. Thirty patients with supine diastolic blood pressure between 90 and 114 mm Hg during single-blind placebo therapy were randomized to double-blind treatment with either doxazosin or further placebo in a parallel-design protocol. Starting at one mg, dosage was doubled every 2 weeks during a 10-week treatment period to a maximum dose of 16 mg once daily. Blood was sampled in the fasting state before and during double-blind therapy for measurement of total cholesterol and triglycerides, cholesterol in the lipoprotein fractions, and apolipoproteins A and B. At the end of 10 weeks of titration, systolic and diastolic blood pressure were each reduced by 14 mm Hg in the standing position when measured 24 hours following the previous dose. Supine pressure was lowered by 6 mm Hg systolic and by 5 mm Hg diastolic at the same time point. Measured hourly for 12 hours following the ingestion of doxazosin, blood pressure was lowered maximally at 4-5 hours when an additional decline of 14/6 mm Hg (systolic/diastolic) was observed in the standing position and 13/6 in the supine posture. Postural dizziness, the most frequent symptomatic complaint, was reported in 4 patients during doxazosin treatment. After brief interruption of treatment in one and dosage adjustment in another, titration was continued in all four and no patient was withdrawn because of side effects. Concerning lipoproteins, the ratio of total cholesterol to HDL cholesterol and of LDL to HDL cholesterol both improved during treatment with doxazosin.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the effects of doxazosin and atenolol on blood pressure and blood lipids: a one-year, double-blind study in 228 hypertensive patients

The efficacy and toleration of doxazosin and atenolol were compared over a 52-week period in a double-blind, multicenter study of 228 patients with mild-to-moderate hypertension. Over the treatment period, both drugs significantly reduced blood pressure, and there were no clinically or statistically significant differences between treatment groups for reductions in standing systolic and diastolic blood pressures or in sitting diastolic blood pressure. However, atenolol treatment caused significantly greater reductions in sitting systolic blood pressure and heart rate. Neither drug significantly affected total serum cholesterol concentrations. Doxazosin treatment lowered serum triglycerides, whereas atenolol treatment produced an increase in serum triglycerides (p less than 0.001, week 30; p less than 0.01, week 50, between treatment groups). Increases in high-density lipoprotein cholesterol and high-density lipoprotein to total cholesterol ratio were obtained with doxazosin treatment, whereas atenolol treatment decreased these lipid fractions (p less than 0.0001, weeks 30 and 50, between treatment groups). Using the Framingham equation, it was calculated that at week 50 the risk of developing coronary heart disease was reduced by 22% for the group taking doxazosin (p less than 0.001 vs baseline) and by 4% (not significant) for patients taking atenolol (p = 0.01, between treatment groups). It is concluded that doxazosin is a well-tolerated and effective antihypertensive drug with a favorable effect on blood lipids. Doxazosin provides an attractive, new alternative first-line drug for the treatment of mild-to-moderate hypertension.

The addition of doxazosin to the treatment regimen of hypertensive patients not responsive to nifedipine

The efficacy and safety of doxazosin, a selective alpha 1-inhibitor, were assessed in hypertensive patients who failed to respond to nifedipine. Fifty patients were entered into a study that involved three phases: (1) a 2-week baseline period, (2) a 10-week period in which patients received doxazosin, 1 to 8 mg, once daily, and (3) a 4-week maintenance period. After 14 weeks, all 43 efficacy evaluable patients were considered therapy successes (sitting diastolic blood pressure either less than or equal to 90 mm Hg or greater than or equal to 10 mm Hg reduction) at a mean daily dose of 3.1 mg. Ninety-three percent achieved blood pressure control (sitting diastolic blood pressure less than or equal to 90 mm Hg) at a mean dose of 3.1 mg once daily. By the final treatment visit, sitting systolic and diastolic blood pressures of efficacy evaluable patients were reduced (p less than 0.05) by 16/18 mm Hg from a mean baseline of 157/103 mm Hg to a final value of 141/85 mm Hg. The most prevalent side effect was vertigo (six patients). Most side effects were mild or moderate and disappeared or were tolerated with continued therapy. No clinically significant laboratory changes were apparent, and no trends were observed with regard to organ systems or correlations with dose or duration of treatment. The investigators' global assessment was excellent or good for 98% of patients for both efficacy and toleration. From baseline to final visit there was a highly significant reduction of 17% (p less than 0.001) in the calculated coronary heart disease risk score, which was based on the Framingham equation.

A single-blind study of doxazosin in the treatment of essential hypertension when added to nonresponders to angiotensin-converting enzyme inhibitor therapy

Doxazosin, a selective alpha 1-inhibitor, was assessed in hypertensive patients with sitting diastolic blood pressures (DBPs) of 95 to 114 mm Hg while receiving a stable dose of captopril or enalapril. Fifty-six patients were entered into the study that involved three phases: (1) a 2-week baseline period, (2) a 10-week period in which patients received doxazosin, 1 to 8 mg, once daily, and (3) a 4-week maintenance period. After 14 weeks of doxazosin treatment, 95% of the patients were therapy successes (sitting DBP either less than or equal to 90 mm Hg with greater than or equal to 5 mm Hg reduction or greater than or equal to 10 mm Hg reduction) at a mean daily dose of 2.4 mg. Ninety-three percent achieved blood pressure control (sitting DBP less than or equal to 90 mm Hg) at a mean dose of 2.3 mg once daily. By the final treatment visit, systolic/diastolic sitting blood pressures for efficacy evaluable patients were reduced by 16/17 mm Hg from a mean baseline of 158/101 mm Hg to a final value of 143/84 mm Hg. Throughout the study (2 to 14 weeks), all blood pressure reductions from baseline were significant (p less than 0.05). There was only one side effect (vertigo) that warranted dose reduction, and only one patient was withdrawn from therapy (nausea). Most side effects were mild or moderate and disappeared or were tolerated with continued therapy. No clinically significant laboratory changes were apparent, and no trends were observed with regard to organ systems or correlations with dose or duration of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Doxazosin in the treatment of mild and moderate essential hypertension in general medical practice

Doxazosin, a selective alpha 1-inhibitor, was assessed in 34 patients with mild and moderate hypertension. This study involved three phases: (1) a 2-week baseline period, (2) an 8-week period in which patients received 1 to 8 mg of doxazosin once daily, and (3) a 4-week maintenance period. After 12 weeks, 77% of the efficacy evaluable patients were considered therapy successes (sitting diastolic blood pressure either less than or equal to 90 mm Hg with greater than or equal to 5 mm Hg reduction or greater than or equal to 10 mm Hg reduction) at a mean daily dose of 4.3 mg. Sixty-one percent achieved blood pressure control (sitting diastolic blood pressure less than or equal to 90 mm Hg) at a mean dose of 3.7 mg once daily. By the final treatment visit, systolic/diastolic blood pressures of efficacy evaluable patients were reduced by 17/12 and 17/11 mm Hg from a mean baseline of 160/100 and 156/101 mm Hg in the sitting and standing positions, respectively (p less than 0.05). Of the 34 patients, nine (26%) reported 12 adverse experiences, of which only one was severe. No clinically significant laboratory changes were apparent, and no trends were observed with regard to organ systems or correlations with dose or duration of treatment. The investigator's global assessment of efficacy of once-daily doxazosin therapy was excellent or good for 85% of patients and fair for 15% of patients. The investigator's global assessment of toleration was excellent or good for 91% of patients and fair for 9% of patients. The overall lipid profile indicated a decrease in total cholesterol and triglycerides.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of doxazosin and enalapril in the treatment of mild and moderate essential hypertension

The antihypertensive efficacy and safety of doxazosin, a selective alpha 1-adrenoceptor antagonist, were compared with that of the angiotensin-converting enzyme inhibitor enalapril in an 18-week double-blind, parallel-group trial. Sixty-seven hypertensive patients entered the three-phase study, which involved a 4-week placebo washout period, a 10-week titration period with doxazosin, 1 to 16 mg, or enalapril, 10 to 40 mg once daily followed by a 4-week maintenance period. The target response was a standing diastolic blood pressure less than or equal to 90 mm Hg. In the 62 efficacy evaluable patients the mean final daily dose of doxazosin was 5.6 mg and 25.5 mg for enalapril. The percentages of therapeutic successes were 74% in the doxazosin- and 81% in the enalapril-treated groups; the proportions in whom standing diastolic blood pressure less than or equal to 90 mm Hg were 55% and 61%, respectively. Both sitting and standing blood pressures were significantly reduced at all visits during the 14-week treatment period in both groups. Twelve patients receiving doxazosin reported 14 adverse events and nine patients administered enalapril reported 19 adverse events; therapy was stopped in three patients in each group because of side effects. The overall assessment of efficacy was excellent or good for 71% of the doxazosin-treated and 67% of the enalapril-treated patients, respectively. Toleration of therapy was excellent or good for 91% of the doxazosin-treated and 88% of the enalapril-treated patients, respectively. No clinically significant changes were observed in the serum lipids, plasma biochemistry, or hematologic profiles.(ABSTRACT TRUNCATED AT 250 WORDS)

Doxazosin in the treatment of patients with mild or moderate hypertension and mild or moderate renal insufficiency

The antihypertensive efficacy and safety of doxazosin, a selective alpha 1-inhibitor, were assessed in 23 hypertensive patients with renal insufficiency. The study involved three phases: (1) a 2-week baseline period, (2) a 10-week period during which patients received doxazosin, 1 to 16 mg, once daily, and (3) a 4-week maintenance period. After 14 weeks of active treatment, systolic/diastolic blood pressures of efficacy evaluable patients were reduced by 8.9/9.2 and 4.6/9.1 mm Hg to final values of 153/90 and 149/91 mm Hg in the supine and standing positions, respectively. The mean dose of the efficacy evaluable patients was 9.8 mg/day. Eleven patients experienced one or more side effects, most of which were mild or moderate and disappeared or were tolerated with continued therapy. No clinically significant laboratory changes were apparent, and no trends were observed with regard to organ systems or correlations with dose or duration of treatment. There were no significant differences in serum creatinine levels between baseline and final visits. The overall lipid profile indicated a decrease in total cholesterol with increases in high-density lipoprotein cholesterol and the high-density lipoprotein/total cholesterol ratio. From baseline to final visit there was a highly significant reduction of 19% (p less than 0.05) in calculated risk scores for coronary heart disease on the basis of the Framingham equation.

New alpha 1-adrenergic receptor antagonists for the treatment of hypertension: role of vascular alpha receptors in the control of peripheral resistance

The pharmacology, clinical efficacy and safety of new alpha-adrenergic receptor antagonists for the treatment of hypertension was reviewed (Table XIV). Although all these agents block alpha 1 receptors, some of them have additional effects on histamine, serotonin, dopamine, and alpha 2 receptors. These other actions account for the differences in the side effect profiles observed, i.e., increased incidence of central nervous system side effects found with indoramin, ketanserin, and urapidil, as well as for some additional beneficial effects of ketanserin (i.e., antiplatelet aggregation activity). The magnitude of BP reduction observed with antagonists of alpha 1-adrenergic receptors is modest. In most studies, the degree of BP reduction is comparable to that of prazosin, but less than that achieved with thiazide diuretics, beta-receptor antagonists, or methyldopa. Studies on the comparative efficacy and safety of new alpha 1 antagonists with converting enzyme inhibitors or calcium-channel blockers are not available. In general, alpha 1 antagonists produce greater reductions in standing than in supine BP, an effect due to the venodilatory action of these drugs. New alpha 1 antagonists appear to have equal efficacy in black and white hypertensive individuals. Their comparative efficacy and safety in young vs elderly hypertensive individuals requires further investigation. No information about the possible development of tolerance during treatment with new alpha 1 blockers was encountered. The effects of alpha 1 antagonists on HR are variable and depend on how long after the oral dose the measurements were obtained. In most studies, no significant HR changes are noticed for readings obtained 24 hours post dose; whereas tachycardia has been observed at the time of peak hypotension. Since alpha 1 antagonist-induced tachycardia is most likely of reflex nature, i.e., mediated to an increase in sympathetic activity, the increased HR may be associated with increases in myocardial contractility and in myocardial oxygen consumption. Consequently, a 24-hour HR monitoring during treatment with alpha 1 antagonists should be required for evaluation of new agents. The hemodynamic, humoral, and hormonal effects of the newer alpha 1-receptor antagonists are comparable to those of prazosin. The most consistent finding is a reduction in total peripheral resistance associated with either no change or with only small increases in cardiac index. These agents have been shown either not to change or to increase renal blood flow.(ABSTRACT TRUNCATED AT 400 WORDS)

Studies of serum lipids in hypercholesterolaemic rabbits treated with doxazosin

Serum lipids were studied in hypercholesterolaemic rabbits treated with the selective alpha 1-adrenoreceptor antagonist doxazosin. Hypercholesterolaemia had been induced by cholesterol feeding which raised mean (+/- SEM) total serum cholesterol from 1.4 (+/- 0.1) mmol/l to 84.1 (+/- 3.6) mmol/l. A cross-over design was used to compare the effect of doxazosin with placebo in 20 rabbits of which 16 completed the study. Doxazosin (2 mg/kg) or placebo vehicle was administered subcutaneously once daily for three weeks. Compared with placebo, doxazosin produced an 8.6% greater reduction in total serum cholesterol. This difference did not, however, reach statistical significance.

Doxazosin. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in mild or moderate hypertension

Doxazosin is a long-acting selective alpha 1-adrenoceptor antagonist structurally related to prazosin. Like prazosin, doxazosin exerts its antihypertensive effect by reducing total peripheral resistance by selective postsynaptic alpha 1-blockade, without reducing cardiac output, and similarly, doxazosin appears to have a negligible effect on heart rate. Doxazosin differs from prazosin in that its long half-life enables once-a-day oral administration. Doxazosin significantly lowers both standing and supine blood pressure and appears to maintain this antihypertensive effect over a 24-hour dosing interval. Doxazosin 1 to 16 mg once daily has been found to be comparable in efficacy to atenolol 50 to 100 mg and prazosin 1 to 20 mg daily. Characteristic of alpha 1-adrenoceptor antagonists, doxazosin also has favourable effects on the plasma lipid profile in that it decreases total cholesterol and triglycerides, and increases high density lipoprotein (HDL) cholesterol as well as the HDL/total cholesterol ratio. Although further long term trials are needed to clarify the role of doxazosin in multidrug regimens in more severe hypertension, it appears to be a suitable drug for consideration as first-line therapy in mild to moderate essential hypertension.

24-hour control of blood pressure by once daily doxazosin: a multicentre double-blind comparison with placebo

The antihypertensive efficacy of the new, once daily, alpha 1-adrenoceptor inhibitor, doxazosin, was compared with placebo in 40 patients with mild to moderate hypertension. Following a dose titration the mean final daily doxazosin dose in 20 patients was 13.1 mg. Through-the-day blood pressure control was assessed by frequent measurements during 24 h hospitalisation in the 9 th week of double-blind treatment compared with similar measurements made during a 2 week single-blind placebo run-in. Mean reductions in standing and supine systolic and diastolic blood pressure during doxazosin treatment were statistically significantly greater than during placebo treatment at most hourly time points during the 24 h post-dose period. Twenty-four post-dose the mean falls in standing and supine diastolic blood pressure during doxazosin treatment were statistically significant when compared with placebo. Adverse effects during doxazosin treatment were generally minor and were tolerated or disappeared with continued therapy. No patients were withdrawn from the study due to adverse effects. We conclude that once daily doxazosin provides smooth and effective blood pressure control throughout a 24 h post-dose period.

Serum lipoproteins during treatment with antihypertensive drugs

Hypertension and certain alterations in serum lipoproteins such as a decrease in high density lipoprotein-cholesterol (HDL-C), an increase in low density lipoprotein-cholesterol (LDL-C) and perhaps also elevated triglycerides (Tg), are complementary coronary risk factors. Moreover, it has become evident that several of the drugs used for standard antihypertensive therapy may also interact with lipoprotein metabolism. The following has been observed after 1 to 12 months of treatment. Various diuretics can significantly increase LDL-C and/or very LDL-C and total C/HDL-C ratio, while HDL-C is often largely unchanged; Tg also are often elevated. LDL-C increased in diuretic-treated men and in chlorthalidone-treated postmenopausal women but not in chlorthalidone-treated premenopausal women. The latter may be protected from this side effect. Drug dosages were usually high in these studies. Indapamide, given at a dose of 2.5 mg/day, seems to exert no relevant effect on the lipoproteins. It is not established whether this difference is related to the nature of the drugs or the doses used. There is little doubt that the dose of chlorthalidone used was greater than that required for a full antihypertensive effect of this drug. Several beta-blockers given as monotherapy induce significant increases in Tg and a tendency for decreases in HDL-C. These changes are most prominent on non-selective beta 1+2-blockers without partial intrinsic sympathomimetic activity (ISA), less pronounced on highly selective beta 1-blockers without ISA, and even more discrete or absent on beta-blockers with distinct ISA. Other sympatholytics such as reserpine, methyldopa, debrisoquine, urapidil, clonidine, labetalol, or postsynaptic alpha-blockers (prazosin, trimazosin, doxazosin etc.) did not affect or, postsynaptic alpha-blockers in particular, sometimes even slightly decreased Tg or LDL-C and very LDL-C values. During combination therapy, diuretic-induced increases in LDL-C were at short term prevented or reversed by the concomitant administration of certain beta-blockers, but not by sympatholytics such as reserpine, methyldopa or clonidine. With combined diuretic-prazosin treatment, a tendency for slightly higher HDL-C was reported. Angiotensin converting enzyme inhibitors (captopril, enalapril) and calcium channel blockers (verapamil, nifedipine, nitrendipine, diltiazem) seem to be largely devoid of undesirable effects on serum lipoproteins. Monotherapy with the potent direct vasodilator carprazidil improved blood pressure and significantly increased HDL-C. Whether and to what extent the observed variations in lipoproteins may persist beyond 1 year of treatment is as yet unclear.(ABSTRACT TRUNCATED AT 400 WORDS)

A double-blind and cross-over comparison of once daily doxazosin and placebo with steady-state pharmacokinetics in elderly hypertensive patients

The alpha 1-adrenoceptor antagonist doxazosin has been compared with placebo in 40 elderly hypertensive patients (mean age 71.4 years). At the end of 10 weeks once daily treatment with doxazosin the mean 24-h post-dose changes in standing and supine blood pressure compared with placebo were -6.9/-5.6 mmHg (systolic/diastolic) and -6.2/-5.5 mmHg respectively. The reductions in standing and supine diastolic blood pressures were statistically significant compared with placebo. At the end of treatment steady-state pharmaco-kinetics were evaluated in 18 patients. The plasma elimination half-life during the dose interval in these patients was 16.1 h (range 10.1-27.1 h) and the median time to peak plasma concentration was 3 h (range 1-4 h). One patient was withdrawn because of adverse effects (headache, weakness, and sweating) during doxazosin treatment. Once daily doxazosin reduced diastolic blood pressure and was well tolerated in these elderly hypertensive patients.

The influence of non-beta-blocking drugs on the lipid profile: are diuretics outclassed as initial therapy for hypertension?

Diuretic drugs, when used in the treatment of hypertension, raise the blood concentrations of total cholesterol and low-density or very low-density lipoprotein cholesterol. Triglycerides often increase as well. Thiazide, phthalimidine, loop, potassium-sparing, and methylindoline drugs produce a similar effect. Only indapamide, a methylindoline agent with vasodilator activity, has been free of adverse lipid effects. It remains unclear whether it is the low dose of indapamide or some other quality that frees it of this effect. In long-term diuretic therapy, total cholesterol returns to, or below, baseline values, suggesting that the lipid elevations are transitory. However, in studies with adequate control groups, total cholesterol declines below baseline valves in control subjects such that an adverse differential in lipid values persists in long-term treatment. Selective alpha-1-adrenoceptor-blocking drugs cause no change or favorable alterations in lipid concentrations in short-term and long-term (1 year) treatment. Among all antihypertensive drugs, this class of agents, and especially prazosin, has produced the most consistently salutary lipid and metabolic effects. Although less well examined, guanabenz, clonidine, guanfacine, and diltiazem have been associated with favorable lipid changes. Captopril and nifedipine have caused no change in lipid-lipoprotein values in limited investigations. These agents are preferable to diuretics and certain beta blockers with respect to short-term effects on lipids and lipoproteins. Their ultimate superiority as monotherapy depends on whether they lower blood pressure equally well. Lowering of the probability of coronary heart disease in hypertensive patients depends as much on blood pressure control as on lipid effects.(ABSTRACT TRUNCATED AT 250 WORDS)

A multicenter trial of doxazosin in West Germany

The antihypertensive efficacy and safety of the new long-acting selective alpha 1 inhibitor doxazosin were assessed in patients seen in clinical practice. A total of 232 mild to moderate hypertensive patients were treated by 35 physicians. After an initial 2-week period (phase 1) during which eligibility to enter the study was determined (diastolic blood pressure [BP] of 95 to 114 mm Hg), all patients received doxazosin 1 to 8 mg once daily for 8 weeks (phase 2). Patients were then maintained for another 4 weeks on the dosage necessary to control diastolic BP to less than or equal to 90 mm Hg (phase 3). Efficacy and toleration of doxazosin therapy during the study period were good; 81% of evaluable patients (n = 180) achieved BP control with a once-daily mean dosage of 3.3 mg. At the end of phase 2 BPs were reduced by (systolic/diastolic) 23.8/17.3 (sitting) and 23.7/17.1 mm Hg (standing). Side effects were generally mild to moderate and either were tolerated or disappeared with continued therapy; 7 patients withdrew from the study because of intolerable side effects. Overall results demonstrated that doxazosin is suitable for treatment of mild to moderate hypertension and can be administered on a once-daily basis, which enhances compliance.

Comparative effects of doxazosin and hydrochlorothiazide on serum lipids and blood pressure in essential hypertension

The efficacy and safety of doxazosin (mean dosage 6.9 mg, range 1 to 16) in the treatment of essential hypertension were compared in a double-blind study with those of hydrochlorothiazide (HCTZ) (mean dosage, 84.6 mg, range 25 to 100) in 104 hypertensive patients treated once daily for 6 months. Thirty-five patients were also assessed for comparative effects of the 2 agents on serum lipid parameters. Doxazosin produced potentially favorable changes from baseline in the concentrations of serum lipid fractions (total triglycerides, total cholesterol, high density lipoprotein [HDL] cholesterol and the derived HDL/total cholesterol ratio) compared with HCTZ. The decreases in total triglyceride and total cholesterol concentrations and an increase in the HDL/total cholesterol ratio were significantly different (p less than 0.006) from the opposite changes observed with HCTZ. Clinically relevant decreases from baseline in supine and standing blood pressures at 24 hours after administration did not significantly differ between the 2 agents. The incidence and severity of side effects were similar for both drugs. Three patients receiving doxazosin and 6 receiving HCTZ were withdrawn due to drug-related clinical side effects including 2 patients receiving HCTZ who were withdrawn because of laboratory test abnormalities. Eight HCTZ- and 1 doxazosin-treated patients developed hypokalemia and 6 HCTZ-treated patients developed hyperuricemia. These findings indicate that doxazosin and HCTZ provide comparable antihypertensive efficacy after 6 months of treatment using a once-daily regimen, but doxazosin produces a beneficial effect on the serum lipid profile as well as fewer biochemical aberrations.

An open one-year comparison of doxazosin and prazosin for mild to moderate essential hypertension

The long-term safety, efficacy and effect on serum lipid profile of doxazosin, a new alpha 1-adrenoceptor inhibitor administered once daily, were compared with those of prazosin, administered twice daily, in 104 patients with essential hypertension treated for 1 year. Doxazosin produced clinically significant decreases in standing and supine blood pressures over a period of 1 year. These decreases were similar to those produced after an initial period of 12 weeks of double-blind therapy. The reductions in blood pressure produced by doxazosin were greater than those produced by prazosin. Minor and clinically nonsignificant changes in heart rate were observed with both drugs. The favorable changes from baseline in plasma lipid concentrations observed after 12 weeks of double-blind therapy were maintained throughout the 1-year open study. These were average increases in the mean high density lipoprotein cholesterol concentration and the derived high density lipoprotein/total cholesterol ratio, and average decreases in total cholesterol and total triglyceride concentrations. The incidence of side effects reported was similar for doxazosin and prazosin. Most were rated as being mild or moderate in severity and were tolerated or disappeared with continued therapy. Results of laboratory tests, electrocardiograms, ophthalmoscopy and body weight measurements revealed only minor changes from baseline, and none was judged to be of clinical significance. These findings demonstrate that doxazosin is a safe and effective antihypertensive agent suitable for once-daily dosing, and has favorable effects on the serum lipid profile.

Multicenter, double-blind comparison of doxazosin and atenolol in patients with mild to moderate hypertension

In a double-blind multicenter study, the new alpha 1-adrenoceptor inhibitor doxazosin was compared with atenolol for efficacy, safety and effect on serum lipids. One hundred and twenty-six patients with mild to moderate hypertension were randomly assigned to receive either doxazosin (n = 63) or atenolol (n = 63). The mean final dosages, administered once daily, to obtain 24-hour blood pressure (BP) control were doxazosin 12 mg (range 1 to 16) and atenolol 91.8 mg (range 50 to 100). Of 12 doxazosin and 7 atenolol patient withdrawals from the study, 7 doxazosin and 4 atenolol patients withdrew for treatment-related reasons. No statistically significant differences between treatment groups were found after 20 weeks in changes from baseline in standing and sitting BPs measured 24 hours after administration. Sitting BP (systolic/diastolic) was reduced by 10.5/9.8 mm Hg after doxazosin treatment and by 10.9/10.7 mm Hg after atenolol therapy. Standing BP was reduced by 8.8/7.7 mm Hg after doxazosin administration and 9.7/9.3 mm Hg after treatment with atenolol. Supine BP was measured in a small cohort of the study population, and doxazosin had a smaller effect than atenolol. After 20 weeks of treatment, both drugs reduced heart rate with atenolol producing a statistically significantly greater decrease than doxazosin (standing, doxazosin 5 beats/min, atenolol 16.2 beats/min, p less than 0.001; sitting, doxazosin 5 beats/min, atenolol 13.1 beats/min, p less than 0.001). Side effects were reported by 37 patients receiving doxazosin therapy and 34 patients receiving atenolol therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of antihypertensive drugs on serum lipids and lipoproteins. II. Non-diuretic drugs

This review examines the effects of various antihypertensive drugs on blood lipids, lipoproteins, and apolipoproteins. A large number of studies have documented the elevation of total cholesterol, triglycerides, low density lipoprotein (LDL) cholesterol, and very-low density lipoprotein (VLDL) cholesterol with many thiazide-type diuretic drugs, albeit mainly in short term studies. When added to thiazide diuretics, both beta 1-selective and non-selective beta-blocking drugs elevate total triglycerides and VLDL triglycerides, lower high density lipoprotein (HDL) cholesterol and raise the ratio of total cholesterol to HDL cholesterol ratio. Most non-selective beta-blockers have similar effects when used as monotherapy, but the beta 1-selective agents appear not to affect HDL cholesterol in monotherapy. Prazosin appears free of adverse lipid effects and has improved lipid-lipoprotein concentrations in many studies. Preliminary data on several other drugs also suggest a favourable lipid profile and additional study is warranted - among these are guanabenz, clonidine, pindolol, labetalol, indapamide, and guanfacine. Elevations in serum triglycerides are often ignored on various counts, but triglycerides have been found to be a strong risk factor in European studies and in women over the age of 50 years in the Framingham study. Despite the unfavourable short term effects of diuretics, the theoretical risk of the lipid-lipoprotein changes remains unclear because HDL cholesterol and the total cholesterol to HDL cholesterol ratio are often unchanged. For this and other reasons, a long term trial comparing thiazide-type diuretics with drugs with the most favourable lipid-lipoprotein profile is needed. Until this is accomplished, in most settings diuretic-based regimens are still preferred initially since they are of proven, if limited, efficacy against the cardiovascular complications of hypertension.

The antihypertensive effects of doxazosin: a clinical overview

Doxazosin is a long-acting selective alpha 1-adrenoceptor antagonist which has been shown to be effective and well tolerated in the treatment of hypertension given in once-daily doses as monotherapy for up to 1 year or as an adjunct to thiazide or beta-adrenoceptor blockers. Doxazosin has a pharmacokinetic profile in both young adult and elderly subjects which is compatible with once-daily administration. This has been confirmed by measurement of steady state pharmacokinetics in patients receiving long-term doxazosin therapy. In controlled double-blind studies involving approximately 550 patients on doxazosin 1-16 mg once daily, significant reductions in both standing and supine BP were maintained throughout the 24 h dosing interval. Effectiveness of doxazosin in terms of BP lowering and proportion of responders was similar to that achieved with hydrochlorothiazide 25-100 mg once daily, atenolol 50-100 mg once daily, nadolol 40-160 mg once daily, metoprolol 100-200 mg per day given twice daily, or prazosin 1-20 mg per day given twice daily. Doxazosin was as effective in elderly patients as in the younger age group and was as effective in blacks as in caucasians. Doxazosin was well tolerated. Side-effects were generally mild to moderate in severity. Overall incidence, including postural effects early in treatment, was similar to that seen with the comparative agents. In comparison with placebo, doxazosin favourably increased (P less than 0.05) the HDL/total cholesterol ratio.(ABSTRACT TRUNCATED AT 250 WORDS)