Doxazosin in physiologically and pharmacologically normotensive men with benign prostatic hyperplasia

Role of α1-blockers in the current management of hypertension

There is emerging evidence that α1-blockers can be safely used in the treatment of hypertension. These drugs can be used in almost all hypertensive patients for blood pressure control. However, there are several special indications. Benign prostatic hyperplasia is a compelling indication of α1-blockers, because of the dual treatment effect on both high blood pressure and lower urinary tract symptoms. Many patients with resistant hypertension would require α1-blockers as add-on therapy. Primary aldosteronism screen is a rapidly increasing clinical demand in the management of hypertension, where α1-blockers are useful for blood pressure control in the preparation for the measurement of plasma aldosterone and renin. Nonetheless, α1-blockers have to be used under several considerations. Among the currently available agents, only long-acting α1-blockers, such as doxazosin gastrointestinal therapeutic system 4-8 mg daily and terazosin 2-4 mg daily, should be chosen. Orthostatic hypotension is a concern with the use of α1-blockers especially in the elderly, and requires careful initial bedtime dosing and avoiding overdosing. Fluid retention is potentially also a concern, which may be overcome by combining an α1-blocker with a diuretic.

Clinical Efficacy and Safety of Naftopidil Treatment for Patients with Benign Prostatic Hyperplasia and Hypertension: A Prospective, Open-Label Study

PURPOSE

To investigate the efficacy and safety of naftopidil for benign prostatic hyperplasia (BPH) patients, mainly focusing on changes in blood pressure (BP).

MATERIALS AND METHODS

Of a total of 118 patients, 90 normotensive (NT) and 28 hypertensive (HT) patients were randomly assigned to be treated with naftopidil 50 mg or 75 mg for 12 weeks, once-daily. Safety and efficacy were assessed by analyzing changes from baseline in systolic/diastolic BP and total International Prostate Symptom Score (IPSS) at 4 and 12 weeks. Adverse events (AEs), obstructive/irritative subscores, quality of life (QoL) score, maximum urinary flow rate (Qmax), and benefit, satisfaction with treatment, and willingness to continue treatment (BSW) questionnaire were also analyzed.

RESULTS

Naftopidil treatment decreased mean systolic BP by 18.7 mm Hg for the HT 50 mg group (p<0.001) and by 18.3 mm Hg for the HT 75 mg group (p<0.001) and mean diastolic BP by 17.5 mm Hg for the HT 50 mg group (p<0.001) and by 14.7 mm Hg for the HT 75 mg group (p=0.022). In the NT groups (both naftopidil 50 mg and 75 mg), naftopidil elicited no significant changes in BP from baseline values. After 12 weeks, naftopidil 50 and 75 mg groups showed significant improvements in IPSS scores (total, obstructive/irritative subscores, QoL score) and Qmax from baseline. AEs were reported in 7.8% (50 mg group) and 2.9% (75 mg group) of patients. In both the 50 mg and 75 mg groups, >86% of all patients agreed to continue their current medications.

CONCLUSION

Our results suggest that naftopidil treatment in BPH patients with hypertension allows for optimal management of BP within the normal range.

Commentary: Doxazosin for alcoholism

Recent preclinical and clinical evidence using prazosin indicates that α(1) -blockade may represent a new approach to treat alcohol dependence (AD). While most of the alcohol research on α(1) -blockade has been conducted testing prazosin, O'Neil and colleagues recently performed a set of preclinical experiments testing another α(1) -blocker, doxazosin, which has a longer half-life that may enhance clinical utility. Doxazosin and prazosin share the same chemical structure, in which the central element is a piperazine ring. O'Neil and colleagues' main results are that doxazosin significantly reduced alcohol intake without affecting locomotor activity. As such, O'Neil and colleagues provide the first preclinical evidence of the possible role of doxazosin in AD. Additional translational research is needed to further test this hypothesis.

Efficacy and safety of tamsulosin hydrochloride compared to doxazosin in the treatment of Indonesian patients with lower urinary tract symptoms due to benign prostatic hyperplasia

AIM

The objective of the study was to compare the efficacy and safety of tamsulosin hydrochloride and doxazosin in patients with lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH).

METHODS

The safety and efficacy of tamsulosin (0.2 mg) and doxazosin (2 mg) was determined after once daily administration for 6 weeks in an open-label, randomized, multicenter study of 101 men with BPH. The International Prostatic Symptom Score (IPSS), maximal urinary flow rates (Qmax), average urinary flow rates (Qave) and residual urine were determined at baseline and again at 6 weeks as efficacy parameters. The primary parameters used for safety evaluation were vital signs (blood pressure and heart rate) and adverse events. The number of patients with a clinically significant response to treatment with tamsulosin or doxazosin was determined and defined as those with >20% improvement from the baseline Qmax or >20% decrease in total IPSS.

RESULTS

The total IPSS decreased significantly in both the tamsulosin and doxazosin groups compared to baseline. There was a significant difference in the decrease in total IPSS between two groups. Qmax, Qave and residual urine significantly improved only in the tamsulosin group. There were no significant differences in systolic blood pressure, diastolic blood pressure or heart rate profile in the tamsulosin group; however, doxazosin resulted in a significant difference in systolic and diastolic blood pressure. Tamsulosin was well tolerated; only three patients (6%) in the tamsulosin group reported an adverse event (dizziness) while 11 patients (22%) in the doxazosin group reported an adverse event (dizziness), one of whom withdrew from the study.

CONCLUSIONS

Tamsulosin was shown to be more effective than doxazosin in the treatment of LUTS due to BPH.

Long-term follow-up study to evaluate the efficacy and safety of the doxazosin gastrointestinal therapeutic system in patients with benign prostatic hyperplasia with or without concomitant hypertension

OBJECTIVE

To assess the long-term efficacy and safety of extended-release doxazosin gastrointestinal therapeutic system (GITS) under routine clinical care conditions over 12 months in Korean men with benign prostatic hyperplasia (BPH) with and without coexisting hypertension.

PATIENTS AND METHODS

In this open-label, multicentre, uncontrolled, flexible-dose study, 475 men (> or =40 years old) with clinical evidence of BPH were enrolled from 40 centres. Patients were evaluated at baseline and at 1, 2, 6 and 12 months of treatment. The primary efficacy variable was the Clinicians Global Assessment of Change (CGAC; improved, no change, or worse). Secondary efficacy variables were International Prostate Symptom Score (IPSS), quality of life (QoL), maximum urinary flow rate (Q(max)), and postvoid residual (PVR) urine volume. Adverse events (AEs) and blood pressure (BP) were also recorded.

RESULTS

In all, 186 patients completed the study; based on the CGAC, most patients (155, 83.8%) improved and 31 (16.2%) had no change in symptoms. The mean (sd) change in the IPSS and QoL from baseline were -9.0 (6.8) and -1.6 (1.4), respectively (both P < 0.05). The Q(max) and PVR urine volume were significantly better than at baseline, with means of 10.5 (4.3) vs 13.7 (6.3), and 39.1 (37.0) vs 23.2 (33.7); P < 0.05). The decrease in systolic BP (SBP) and diastolic BP (DBP) from baseline in 52 hypertensive patients was significantly greater than in 134 normotensive patients, at (SBP/DBP) -9.5 (18.4)/-13.4 (10.9) vs -3.3 (12.5)/-1.4 (9.5); P < 0.05). A total of 47 AEs were reported in 41 of 475 patients (8.6%); the most common were dizziness (2.7%), erectile dysfunction (1.1%), dry mouth (1.1%), prostatic disorder (0.6%), and postural hypotension (0.4%).

CONCLUSIONS

After 12 months, treatment with doxazosin GITS resulted in an improvement in > 83% of patients based on the CGAC, with significant improvements in IPSS, QoL, Q(max,) and PVR urine volume. Doxazosin GITS was effective and well tolerated as long-term therapy for Korean patients with BPH.

After ALLHAT: doxazosin for the treatment of benign prostatic hyperplasia

Doxazosin mesylate is an alpha1-adrenoceptor antagonist that was used to treat hypertension until a major study (ALLHAT; Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial) showed that it increased the risk of progressing to heart failure. Doxazosin is now being used to treat benign prostatic hyperplasia (BPH). Noradrenaline acts on alpha1-adrenoceptors to contract the smooth muscle in the prostate and bladder, and by opposing these actions, doxazosin is beneficial in BPH. Doxazosin also increases apoptosis in the prostate. Although the standard preparation is suitable for once-daily dosing in BPH, it has to be titrated through three steps to its final dose. The controlled-release gastrointestinal therapeutic system (GITS) formulation of doxazosin is more convenient to use as it only has to be titrated through one step. In the treatment of BPH, standard doxazosin reduced both obstructive and irritative symptoms and increased peak urinary flow rate. The main side effects with doxazosin are those commonly associated with lowering blood pressure, although doxazosin lowers blood pressure to a lesser extent in normotensives than hypertensives. There is some evidence that in addition to being easier to use, doxazosin GITS may cause less adverse effects than the standard preparations. The benefits of doxazosin and the 5alpha-reductase inhibitor, finasteride, may be additive in BPH especially in men with large prostates. Further trials are necessary in order to determine whether doxazosin GITS is superior to other alpha1-adrenoceptor antagonists in BPH.

Clinical ease of using doxazosin in BPH patients with and without hypertension

Clinical studies have demonstrated that doxazosin therapy reduced blood pressure (BP) in patients with benign prostatic hyperplasia (BPH) who were hypertensive at baseline but not in patients who were physiologically or pharmacologically normotensive at baseline. In patients with BPH and uncontrolled hypertension, despite treatment with other antihypertensive drugs, the addition of doxazosin resulted in improved control with significant reductions in BP. The new formulation, doxazosin gastrointestinal therapeutic system (GITS), is initiated at a therapeutic dose, simplifying dose titration. Based on its efficacy and pharmacokinetic and tolerability profiles, doxazosin GITS is an effective and well-tolerated treatment for normotensive and hypertensive patients with BPH.

Doxazosin for benign prostatic hyperplasia: An open-label, baseline-controlled study in Korean general practice

BACKGROUND

Few studies have reported the treatment of benign prostatic hyperplasia (BPH) in Asian patients. We assessed the safety and efficacy of doxazosin, a selective alpha1-adrenoceptor antagonist, in the treatment of Korean patients with symptomatic BPH.

METHODS

Two hundred and ninety-five men, aged 48 years or older with clinical BPH, were enrolled in a 12-week, open-label, baseline-controlled, dose-titration, multicenter study. A 2-week, single-blind, placebo run-in was followed by 10 weeks of doxazosin treatment, initially administered at 1 mg/day, with upward titrations (2, 4, or 8 mg/day) at 2-week intervals. The international prostate symptom score (IPSS) was used to assess efficacy after 4, 6, and 10 weeks of active treatment.

RESULTS

The intent-to-treat (ITT) population comprised 249 patients (mean age 63.6 years). Doxazosin significantly reduced the mean total IPSS by 48%; similarly, the obstructive and irritative subscores were reduced from baseline by 51% and 39%, respectively (P < 0.001 for all scores: Wilcoxon rank sum test). In a subset analysis of 170 normotensive and 78 hypertensive patients, significant reductions in mean systolic and diastolic blood pressures relative to baseline were observed only in the hypertensive subset (P < 0.01). Similar results in mean IPSS were observed in older (> or =65 years, n = 100) and younger (45-64 years, n = 140) patients, as well as between normotensive and hypertensive patients. Thirty-nine patients reported adverse events: The most frequent were dizziness, dyspepsia, asthenia, somnolence, and dry mouth.

CONCLUSIONS

The efficacy and safety of doxazosin treatment for BPH were confirmed in this Asian population. Significant improvements in total IPSS, as well as obstructive and irritative subscores, were observed.

Comparative efficacy of two alpha-adrenoreceptor antagonists, doxazosin and alfuzosin, in patients with lower urinary tract symptoms from benign prostatic enlargement

OBJECTIVES

To compare doxazosin and alfuzosin in patients with moderate to severe lower urinary tract symptoms (LUTS) suggestive of bladder outlet obstruction.

PATIENTS AND METHODS

In all, 210 men with LUTS were randomized to receive doxazosin 1-8 mg once daily or alfuzosin 5-10 mg divided in two or three daily doses in a 14-week, multicentre, double-blind, baseline-controlled, dose-titration study. The International Prostate Symptom Score (IPSS) and maximum urinary flow rate were used to assess the efficacy of the treatment.

RESULTS

At study completion, the mean dose of doxazosin was 6.1 mg/day and alfuzosin 8.8 mg/day. The least squares mean (se) change from baseline in total IPSS was -9.23 (0.6) for doxazosin and -7.45 (0.6) (both P < 0.001) for alfuzosin. The respective mean change from baseline in irritative symptoms was -3.5 (0.2) and -2.8 (0.3) (both P < 0.001). The differences between the treatment groups were statistically significant in favour of doxazosin (total IPSS, P = 0.036; irritative symptoms, P = 0.049). The improvement between groups was also significantly different for postvoid residual urine volume, at -29.19 (8.6) and + 9.59 (8.9) mL for doxazosin and alfuzosin, respectively (P = 0.002). Improvements in mean and maximum urinary flow rates were similar for both treatments, at + 1.5 and + 1.2, and + 2.8 and + 2.5 mL/s, respectively. Doxazosin and alfuzosin were both well tolerated, with most all-cause adverse events reported as mild or moderate.

CONCLUSIONS

The mean doses of doxazosin and alfuzosin used in this study were not equipotent. Doxazosin 6.1 mg/day produced significantly greater improvements than alfuzosin 8.8 mg/day in total and irritative urinary symptom scores and postvoid residual urine volume in men with moderate to severe LUTS. Changes in maximum and mean flow rates were comparable. Doxazosin and alfuzosin were both well tolerated.

Doxazosin added to single-drug therapy in hypertensive patients with benign prostatic hypertrophy

The purpose of this study was to evaluate the efficacy and safety of the addition of doxazosin in the treatment of hypertensive patients who are being treated on another antihypertensive drug. The open-labeled, noncomparative, multicenter study was carried out in 2363 male hypertensive outpatients > 40 years of age, under reasonable control with single antihypertensive drug treatment (diastolic blood pressure < 95 mm Hg), and diagnosed with benign prostatic hypertrophy. Doxazosin was started at a dose of 1 mg/day, which was increased at 2-week intervals to 2 mg/day and 4 mg/day. The study lasted 14 weeks. Blood pressure and heart rate were measured at each of the visits. At baseline and after 14 weeks of treatment, prostatism symptoms were quantified with the International Prostate Symptom Score and quality of life was determined with the American Urology Association Committee Guidelines. Adverse effects were recorded. At the fourth visit, when the patients were taking 4 mg of doxazosin, the blood pressure reduction was 10.7 +/- 3/7.1 +/- 7.1 mm Hg. The decrease in diastolic blood pressure was significantly more marked in patients treated with beta blockers than in patients on calcium antagonists or angiotensin-converting enzyme inhibitors. For systolic blood pressure, decreases were larger in patients treated with diuretics than with calcium antagonists or angiotensin-converting enzyme inhibitors. Prostatism symptoms decreased from 15 +/- 5.8 points to 7.9 +/- 4.3 points (p is less than 0.001) and quality of life improved. Tolerability was good, with only a 4.4% cumulative incidence of adverse effects related to doxazosin. The patients who experienced adverse effects were older and their final blood pressures were lower. The results of this open-label study suggest that the addition of doxazosin to another antihypertensive drug in hypertensive patients with benign prostatic hypertrophy is well tolerated and leads to a reduction in prostatic symptoms. The additional beneficial effects on blood pressure suggest that the use of doxazosin may provide a rational approach to this category of patients.(c)2001 Le Jacq Communications, Inc.

Does the time of administration (morning or evening) affect the tolerability or efficacy of tamsulosin?

OBJECTIVE

To determine whether the time of dosing (morning or evening) affects the tolerability or efficacy of tamsulosin in the treatment of lower urinary tract symptoms.

PATIENTS AND METHODS

Data were analysed from an open-label, observational study in which patients were treated with 0.4 mg tamsulosin once daily for 12 weeks. Treatment effects were determined using the Benign Prostatic Hyperplasia Impact Index, the quality-of-life question of the International Prostate Symptom Score, a similarly phrased question about sexual satisfaction, the maximum urinary flow rate, the postvoid residual urine volume, and the overall efficacy and tolerability. The results were analysed statistically for differences between dosing times, using analysis of covariance for the quantitative variables and logistic regression for the qualitative variables.

RESULTS

While no specific recommendation about the dosing time was given in the trial, the retrospective analysis showed that 4420 and 2087 patients received tamsulosin in the morning and evening, respectively. Both groups had similar values for all variables before treatment. The efficacy and tolerability of tamsulosin treatment was also similar in both groups; there were small advantages for morning dosing, which were statistically significant because there were many patients.

CONCLUSION

In contrast to other alpha-blockers, night-time dosing is not necessary to improve the tolerability or efficacy of tamsulosin.

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.

Doxazosin for benign prostatic hyperplasia in primary care

The incidence of benign prostatic hyperplasia (BPH) is increasing, and an estimated one quarter of men older than 60 years have both BPH and hypertension. Medical management of BPH is now an effective alternative to surgery, and primary care physicians are treating more patients for this condition. Alpha-adrenergic blockers reduce the tone of prostatic smooth muscle, and doxazosin, a selective alpha-1 adrenergic blocker, is effective and well tolerated in the treatment of BPH. Doxazosin can be given in a convenient once-daily dose, and its efficacy is maintained in the long term. Patients with BPH who are already being treated for hypertension with doxazosin need no alteration in their dosage regimen, and doxazosin can be used as a single agent to treat both conditions. Selective alpha-adrenergic blockers are likely to be used increasingly by primary care physicians in the treatment of BPH.

Trends in alpha-blocker treatment of patients with benign prostatic hyperplasia and hypertension: dosing regimens and cost comparisons

Dosing regimen is an important determinant of both drug cost and patient compliance. This retrospective analysis evaluated dosing regimens and drug acquisition costs for 101 patients identified from medical records in a large metropolitan hospital as having hypertension and/or benign prostatic hyperplasia and receiving alpha-blocker therapy with either doxazosin or terazosin. Although once-daily administration is generally recommended for both drugs, 25 (38%) of 66 patients receiving terazosin were treated twice daily compared with 6 (17%) of 35 patients treated twice daily with doxazosin. This difference was statistically significant. The average (mean +/- SD) daily treatment cost per patient for all individuals receiving terazosin during the period of the record review was $1.68 +/- 0.60. For patients treated with doxazosin, the average was $0.96 +/- 0.65-a highly statistically significant result. If all 66 patients receiving terazosin had been converted to doxazosin at the beginning of the study, annual savings would have been $17,345.00. These results demonstrate the importance of reviewing actual dosing regimens. The fact that doxazosin could be administered to a significantly higher percentage of patients once daily rather than twice daily substantially decreased its cost relative to terazosin. A once-daily treatment regimen may also enhance patient compliance, thereby improving the chances of therapeutic success.

Prostatic alpha 1-adrenoceptors and uroselectivity

BACKGROUND

alpha 1-adrenoceptor antagonists (blockers) are now commonly used in the treatment of the symptoms of lower urinary tract obstruction. Originally phenoxybenzamine, a non-selective antagonist at both alpha 1- and alpha 2-adrenoceptors, was used by Marco Caine. In an attempt to minimize side effects, selective alpha 1-antagonists, e.g. prazosin, were subsequently developed. More recently, agents such as alfuzosin, doxazosin, terazosin, and tamsulosin have been introduced and claims of "uroselectivity" and "prostate" selectivity have emerged.

METHODS

This review attempts to put these claims into perspective and represents a comprehensive analysis of all pre-clinical and clinical data including several papers from the Japanese literature. An attempt is made to define what is meant by selectivity at various levels including the test tube, in the laboratory animal and, most importantly, in the clinical context of the whole patient.

CONCLUSIONS

The conclusions are interpreted within the context of the subdivision of the alpha 1-adrenoceptor into alpha 1A, alpha 1B, and alpha 1D subtypes.