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

Blood pressure-lowering effect and duration of action of bedtime administration of doxazosin determined by home blood pressure measurement

The effects and duration of action of bedtime administration of doxazosin 2 mg for 4 weeks on uncontrolled morning home hypertension were investigated. Morning home blood pressure (HBP) was significantly lowered by bedtime administration of doxazosin. Doxazosin significantly lowered evening HBP only in the subgroup of patients with an uncontrolled evening HBP. The evening (E)/morning (M) ratio was greater in patients with an uncontrolled evening HBP than in those with a controlled evening HBP. The results suggest that bedtime administration of doxazosin effectively suppresses morning HBP in uncontrolled morning hypertensives and lowers evening HBP in uncontrolled evening hypertensives.

Usefulness of the .ALPHA.1-Blocker Doxazosin as a Third-Line Antihypertensive Drug

It has been reported that a substantial majority of hypertensives receive insufficient blood pressure (BP) control. As combination therapy for the treatment of hypertension, Ca channel blockers (CCBs), angiotensin II (AII) receptor blockers (ARBs), and/or AII-converting enzyme (ACE) inhibitors are mainly prescribed, while the efficacy of alpha(1)-blockers in such combination therapy remains unknown. The aim of this study was to investigate the efficacy of a low dose of an alpha(1)-blocker added to combination therapy with CCBs and either ARBs or ACE inhibitors for the treatment of hypertension. Subjects were 41 hypertensive patients (23 women and 18 men, mean age 66+/-12 years) who had been followed at the National Kyushu Medical Center. All patients showed poor BP control despite haven taken a combination of CCBs and ARBs or ACE inhibitors for more than 3 months. Doxazosin at a dose of 1 to 2 mg was added to each treatment regimen. The changes in various clinical parameters, including BP and blood chemistry, following the addition of doxazosin were then evaluated. The mean follow-up period was 170 days. BP decreased from 152+/-14/81+/-12 mmHg to 135+/-14/70+/-11 mmHg after the addition of doxazosin at a mean dose of 1.5 mg/day (p<0.001). When good systolic blood pressure (SBP) control was defined as <140 mmHg, the prevalence of patients with good SBP control increased from 24% to 61% (p<0.01). Similarly, the prevalence of patients with good diastolic blood pressure (DBP) control (<90 mmHg) increased from 78% to 98% (p<0.01). Patients whose SBP decreased more than 10 mmHg (n=25) showed significantly higher baseline SBP, serum total cholesterol and low-density lipoprotein (LDL) cholesterol levels compared to those who showed less SBP reduction (<10 mmHg) (n=16, p<0.01). Comparable BP reductions were obtained between obese (body mass index [BMI] > or =25, DeltaBP at 3 months: -15+/-15/-12+/-9 mmHg, n=18) and non-obese (BMI<25, DeltaBP: -14+/-19/-7+/-8 mmHg, n=23) patients. The results suggest that addition of a low dose of the alpha(1)-blocker doxazosin effectively reduces BP in patients taking CCBs and ARBs or ACE inhibitors. Thus, doxazosin seems to be useful as a third-line antihypertensive drug.

Patients with uncontrolled hypertension or concomitant hypertension and benign prostatic hyperplasia

At optimal doses, individual antihypertensive agents lower blood pressure (BP) by an average of 10 mmHg. Many patients with hypertension, including those with stage 3 hypertension, target organ damage, or those at high risk for cardiovascular events and/or adverse effects of high-dose monotherapy, are likely to require combination antihypertensive drug treatment to achieve the recommended systolic/diastolic BP (< 140/90 mmHg). Two studies, a placebo-controlled, double-blind trial (n = 70) and a community-based, open-label trial (n = 491) investigated the antihypertensive efficacy of doxazosin, a long-acting selective alpha1-adrenoceptor blocker, as add-on therapy for uncontrolled hypertension with other antihypertensive medications and in patients with concomitant benign prostatic hyperplasia (BPH) and treated but inadequately controlled hypertension, respectively. The addition of doxazosin to baseline antihypertensive medication(s) significantly lowered BP and had a significantly positive effect on the serum lipid profile. In patients with concomitant BPH, doxazosin significantly improved all BPH symptom scores, regardless of initial symptom severity. Add-on doxazosin sufficiently reduced systolic/diastolic BP such that many patients whose hypertension was previously uncontrolled by other antihypertensive medications were able to reach goal BP (< 140/90 mmHg). Doxazosin as add-on therapy was well tolerated. In conclusion, doxazosin as add-on therapy improves BP control in hypertensive patients not at goal BP and improves lower urinary tract symptoms in patients with concomitant BPH.

Doxazosin as combination therapy for patients with stage 1 and stage 2 hypertension

The purpose of this paper is to review the role of doxazosin, a long-acting alpha(1)-blocker, as a component of combination therapy for patients with stage 1 and stage 2 hypertension and for patients with concomitant hypertension and hyperlipidemia or glucose intolerance. Recent studies that evaluated doxazosin as combination therapy in the treatment of patients with inadequately controlled hypertension and patients with concomitant hypertension and other disorders were reviewed. Data extraction was based on the tolerability and efficacy data of doxazosin in patients with hypertension. Compared with placebo, doxazosin combination therapy leads to significant improvements in sitting and standing blood pressure. Doxazosin is well tolerated, with only minor adverse effects (e.g., headache, dizziness) as the most commonly reported treatment-related complications. The studies described demonstrate that doxazosin is effective as combination therapy for patients with stage 1 and stage 2 hypertension. The positive effects of doxazosin on serum lipids make combination therapy with doxazosin an attractive treatment option for patients who have concomitant hyperlipidemia or glucose intolerance.

The addition of doxazosin to the therapeutic regimen of hypertensive patients inadequately controlled with other antihypertensive medications: a randomized, placebo-controlled study

This randomized, double-blind, placebo-controlled study evaluated the use of doxazosin as an add-on therapy for inadequately controlled hypertension. Patients with a sitting diastolic blood pressure (BP) of 95 to 115 mm Hg received either doxazosin (n = 38) or placebo (n = 32) in addition to one or two baseline antihypertensive medications. After an upward titration period, patients were maintained on a fixed dosage of doxazosin (1 to 16 mg/day) or matching placebo for 4 weeks. Doxazosin add-on therapy led to improvements, compared with placebo, in sitting systolic BP (adjusted mean change = -20.9 v -8.5 mm Hg, P = .001), sitting diastolic BP (-13.0 v -8.1 mm Hg, P = .026), and standing systolic BP (-22.0 v -11.5 mm Hg, P = .011). Baseline antihypertensive therapy was gradually tapered or discontinued in patients who achieved a target reduction in BP (sitting diastolic BP of < 90 mm Hg in addition to a minimum improvement of 10 mm Hg in sitting diastolic BP over baseline) with add-on therapy (55% [n = 21] with doxazosin, 31% [n = 10] with placebo). Twelve patients in the doxazosin group maintained the target reduction in BP after complete withdrawal of their baseline antihypertensive therapy, compared with none in the placebo group. A small but statistically significant positive effect on the lipid profile was seen in the doxazosin group during add-on therapy. Doxazosin treatment was well tolerated, with an adverse event profile similar to that of placebo. These findings demonstrate that doxazosin add-on therapy is an effective, well-tolerated treatment strategy for patients with inadequately controlled hypertension.

A multicenter, community-based study of doxazosin in the treatment of concomitant hypertension and symptomatic benign prostatic hyperplasia: the Hypertension and BPH Intervention Trial (HABIT)

As men age, the incidence of both benign prostatic hyperplasia (BPH) and hypertension increases. Concomitant occurrence of these conditions also increases with age, and the 2 are frequently encountered together in primary care practice. In addition, many patients with hypertension require >1 antihypertensive agent to adequately control blood pressure. In a multicenter, community-based, 8-week, uncontrolled, open-label study, we evaluated doxazosin, a selective alpha1-adrenergic-receptor antagonist, in 491 patients with concomitant symptomatic BPH (American Urological Association [AUA] symptom score > or =12) and hypertension, some previously untreated and some with inadequately controlled hypertension (systolic blood pressure 120-179 mm Hg or diastolic blood pressure [DBP] 80-109 mm Hg) despite taking 1 or 2 antihypertensive agents. Patients were allocated to 1 of 4 groups at baseline according to their diastolic blood pressure (control was considered DBP <90 mm Hg) and whether they had received antihypertensive medication before the study. Thus the 4 groups were treated/well-controlled, treated/poorly controlled, untreated/hypertensive, and untreated/normotensive. In all patient groups, doxazosin therapy significantly improved AUA total symptom and bothersomeness scores and BPH-specific indices of health status and interference with activities (P<0.001). Significant improvements in BPH symptoms were observed with doxazosin, regardless of whether initial symptoms were moderate or severe (P<0.001). Clinically important blood pressure lowering occurred only in the patient groups in which blood pressure had been elevated at baseline. Patients whose blood pressure was poorly controlled at baseline, either without or with treatment (predominantly with angiotensin-converting enzyme inhibitors or calcium channel blockers), achieved adequate blood pressure control (reduction to <140/90 mm Hg) with the addition of doxazosin. Similar improvements in blood pressure and BPH symptoms were seen in both older (> or =65 years) and younger (45 to 64 years) patients, and doxazosin was well tolerated by both groups. The most frequent treatment-related adverse event was dizziness (13.0% of patients); however, patients classified the dizziness as mild in approximately 75% of reports, and severe dizziness was reported by only 2 patients (0.4%). Doxazosin is an effective antihypertensive agent when used in combination with agents from other antihypertensive classes in patients with poorly controlled hypertension and BPH, and is also successful as monotherapy for controlling both BPH and hypertension in patients with mild to moderate hypertension.

Effects of doxazosin in the gastrointestinal therapeutic system formulation versus doxazosin standard and placebo in mild-to-moderate hypertension. Doxazosin Investigators' Study Group

The alpha 1-blocker doxazosin is a well-established therapy for hypertension and benign prostatic hyperplasia; however, in its standard form, a multiple-step titration regimen is usually required. The new gastrointestinal therapeutic system (GITS) formulation of doxazosin greatly minimizes the need for titration by changing drug-delivery rate and the pharmaco-kinetic profile. To demonstrate this in hypertensive patients, we assessed the effects of doxazosin GITS 4 or 8 mg once daily versus doxazosin standard 1-8 mg once daily, and placebo, in an integrated analysis of two multicenter, double-blind, randomized, parallel-group trials. Each trial included a 2-week washout period and 12 weeks of therapy. One study compared doxazosin GITS, doxazosin standard, and placebo in 392 patients with mild hypertension [blood pressure (BP) 95-105/ < or = 180 mm Hg]; the other study compared doxazosin GITS with doxazosin standard in 315 patients with mild-to-moderate hypertension (BP 95-115/ < or = 220 mm Hg). The primary outcome measure was the proportion of responders (sitting diastolic BP < 90 mm Hg or 10-mm Hg decrease from baseline 24 h after the dose) at the final visit for the per-protocol population. Mean baseline BP and heart rate were well matched in each group. Approximately 64% of patients with doxazosin GITS (198 of 309 patients) and 68% with doxazosin standard (207 of 304 patients) achieved goal BP response at the final visit versus 36% with placebo (25 of 70 patients; p < 0.05). The majority with doxazosin GITS (60%) remained at the initial 4-mg starting dose. Doxazosin GITS was as effective as doxazosin standard, and both were more effective than placebo in controlling BP in mild-to-moderate hypertension. Doxazosin GITS was well tolerated, and fewer patients with the GITS formulation discontinued therapy because of side effects compared with doxazosin standard or placebo. Syncope was not reported with doxazosin GITS. Whereas the efficacy of doxazosin GITS at 4 or 8 mg is equivalent to that of the standard regimen in this combined analysis, the GITS formulation appears to eliminate the need for titration in most patients.

Alpha 1-blockers in hypertension

Hypertension is a heterogeneous disease and this is reflected in the marked variability in response to monotherapy. Co-administering antihypertensive therapies has several theoretical benefits, namely enhanced efficacy, improved tolerability, increased compliance and, in some cases, potentially beneficial changes in biochemical variables associated with increased cardiovascular risk, such as improvements in lipid profiles. alpha 1-Blockers, such as doxazosin, have several favourable properties which should be advantageous when used with other agents. Their mechanism of action is complementary to that of each of the other four main groups of antihypertensive drugs and, in each case, enhanced efficacy has been observed when alpha 1-blockade has been added to monotherapy with other drug classes. Synergistic effects have been seen when an alpha 1-blocker is administered together with either a calcium channel blocker or angiotensin-converting enzyme inhibitor. While alpha 1-blockers induce regression of left ventricular hypertrophy, the possibility of enhanced effects during multiple therapy has not been explored. alpha 1-Blockers exert positive effects on lipids (limited data suggest that they are able to reverse the deleterious lipid effects of diuretics and beta-blockers) and exert neutral or positive effects on glucose homeostasis. Further studies are needed to determine whether alpha 1-blockers can alleviate the adverse effects of beta-blockers or diuretics on glucose homeostasis. alpha 1-Blockers, when given concomitantly with other antihypertensive drugs, are well tolerated, conferring advantages with respect to patient compliance. The current data favour the use of alpha 1-blockers as an additional component of antihypertensive therapy, but further studies are needed to address the metabolic and end-organ effects of such treatment regimens.

Tamsulosin treatment of 19,365 patients with lower urinary tract symptoms: does co-morbidity alter tolerability?

PURPOSE

We compare the tolerability and blood pressure effects of 0.4 mg. tamsulosin once daily in patients with lower urinary symptoms suggestive of benign prostatic obstruction with or without concomitant disease and/or antihypertensive medication.

MATERIALS AND METHODS

Data from 2 open label, observational studies (study 1, 9,507 patients treated for 4 weeks and study 2, 9,858 patients treated for 12 weeks) were analyzed for global tolerability and effects on blood pressure stratifying for co-morbidity (none, diabetes, hypertension, other cardiovascular disease) and co-medication (diuretics, beta-blockers, calcium channel blockers, angiotensin converting enzyme inhibitors).

RESULTS

Overall 90 and 95% of patients in studies 1 and 2, respectively, reported good or very good tolerability. While global tolerability was slightly reduced in patients with concomitant disease or some forms of medication (p < 0.05), it was rated as good or very good by more than 90 and 95% of patients even in those groups. In control patients, that is those with neither co-morbidity nor co-medication, the tamsulosin induced blood pressure reductions were similar to those previously reported for placebo treatment but were statistically significant (p < 0.05). Mean additional blood pressure reductions in patients with concomitant disease or medication were not more than 2 mm. Hg.

CONCLUSIONS

Tamsulosin is well tolerated and has marginal effects on blood pressure in the majority of patients. It largely maintains its good global tolerability and minimal blood pressure effects in patients with cardiovascular co-morbidity or diabetes, or those on co-medication with antihypertensive agents.

Alpha 1-blocker combination therapy for hypertension

Combination therapy is a cost-effective and rational approach to treatment of severe hypertension and of mild to moderate hypertension that is refractory to monotherapy. The method has several advantages, most notably improved tolerability and enhanced antihypertensive efficacy. Long-term prospective studies are needed to confirm that such agents as calcium channel blockers, ACE inhibitors, and alpha 1 blockers reduce end-organ damage more effectively than do older antihypertensive drugs. However, scientific evidence strongly suggests that reducing risk factors for end-organ damage reduces heart, brain, kidney, and large-artery injury. Alpha 1 blockers appear to be a particularly suitable choice for use in combination regimens. The only class of agents that should be avoided in combination with alpha 1 blockers is central alpha agonists; all other agents act in an additive or synergistic fashion. Unlike diuretics and beta blockers, alpha 1 blockers do not adversely affect serum lipid, glucose, or insulin levels. In fact, alpha 1 blockers may improve these measurements and also counteract the adverse effects of other antihypertensive agents on them. Alpha1-blocker therapy may bring about regression of LVH, and it does not have deleterious effects on disorders that often coexist with hypertension (e.g., gout, chronic obstructive lung disease, peripheral ischemia).

Tamsulosin treatment of 19,365 patients with lower urinary tract symptoms: does co-morbidity alter tolerability?

PURPOSE

We compare the tolerability and blood pressure effects of 0.4 mg. tamsulosin once daily in patients with lower urinary symptoms suggestive of benign prostatic obstruction with or without concomitant disease and/or antihypertensive medication.

MATERIALS AND METHODS

Data from 2 open label, observational studies (study 1, 9,507 patients treated for 4 weeks and study 2, 9,858 patients treated for 12 weeks) were analyzed for global tolerability and effects on blood pressure stratifying for co-morbidity (none, diabetes, hypertension, other cardiovascular disease) and co-medication (diuretics, beta-blockers, calcium channel blockers, angiotensin converting enzyme inhibitors).

RESULTS

Overall 90 and 95% of patients in studies 1 and 2, respectively, reported good or very good tolerability. While global tolerability was slightly reduced in patients with concomitant disease or some forms of medication (p < 0.05), it was rated as good or very good by more than 90 and 95% of patients even in those groups. In control patients, that is those with neither co-morbidity nor co-medication, the tamsulosin induced blood pressure reductions were similar to those previously reported for placebo treatment but were statistically significant (p < 0.05). Mean additional blood pressure reductions in patients with concomitant disease or medication were not more than 2 mm. Hg.

CONCLUSIONS

Tamsulosin is well tolerated and has marginal effects on blood pressure in the majority of patients. It largely maintains its good global tolerability and minimal blood pressure effects in patients with cardiovascular co-morbidity or diabetes, or those on co-medication with antihypertensive agents.

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)

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.

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.

Issues, goals, and guidelines in selecting first-line drug therapy for hypertension

Modern antihypertensive therapy is enriched by an explosion in drug development that makes available increasingly specific agents whose effects have advanced our understanding of pressor mechanisms. This and other research into hypertensive mechanisms has defined the clinical, pharmacological, and endocrinologic heterogeneity of human hypertension. The sum of these developments is a greatly enhanced ability to identify curable and definable causes of hypertension and to pathophysiologically stratify the remaining cases of essential hypertension. Modern treatment can be much more specific than before. When long-term drug therapy is indicated, the regimen is more likely to achieve a primary goal for each patient, that is, the fewest possible drugs in the smallest amount and in lowest frequency. Two clinically quantifiable mechanisms for long-term arteriolar vasoconstriction can be identified within the spectrum of human hypertension. The first, renin-mediated vasoconstriction, is directly related to the plasma renin level. The second, sodium-volume-related vasoconstriction, is marked by a reciprocally subnormal renin level and involves abnormal sodium retention and calcium transport. A baseline renin-sodium profile can identify the pressure of one of these two forms of vasoconstriction and therefore is the key for the diagnosis of the two curable disorders that fully express one of the two pressor mechanisms--renovascular hypertension and primary aldosteronism. Renovascular hypertension, more common than once thought, is often cured by angioplasty. It is important to diagnose these curable forms before beginning long-term drug therapy. The renin-sodium profile, used in conjunction with serum potassium and creatinine measurements, is valuable not only in screening patients for curable forms, but also for stratifying the remainder according to the pathophysiological vasoconstrictor mechanism that underlies the hypertension. Converting enzyme inhibitors or beta-blockers are, by themselves, often effective in correcting the hypertension of high- or medium-renin patients, whereas calcium antagonists, diuretic agents, or alpha-blockers alone are most effective against the low-renin form of vasoconstriction. In the large midzone of renin values, if monotherapy fails, a rational basis for combined antirenin-antisodium volume therapies can be developed.