Prazosin in the treatment of prostatic obstruction. A placebo-controlled study

Evolving Role of Silodosin for the Treatment of Urological Disorders – A Narrative Review

Use of α-androgenic receptor blockers remains a mainstay therapeutic approach for the treatment of urological diseases. Silodosin is recommended over other α-blockers for the treatment of lower urinary tract symptoms (LUTS) and benign prostate hyperplasia (BPH), due to its high α_1A uroselectivity. Current research data suggest that silodosin is efficacious in the management of various urological diseases. Thus, we herein review the current evidence of silodosin related to its efficacy and tolerability and appraise the available literature that might ultimately aid in management of various urological conditions at routine clinical practice. Literature reveals that silodosin is beneficial in improving nocturia events related to LUTS/BPH. Silodosin exerts effect on relaxing muscles involved in detrusor obstruction, therefore prolonging the need for patients undergoing invasive surgery. Silodosin treatment, either as a monotherapy or combination, significantly improves International Prostate Symptom Score (IPSS) including both storage and voiding symptoms in patients with BPH/LUTS. Patients on other treatment therapies such as phosphodiesterase 5 inhibitors or other α-blockers are well managed with this drug. Steadily, silodosin has proved beneficial in the treatment of other urological disorders such as chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), overactive bladder/acute urinary retention (AUR), premature ejaculation (PE), and prostate cancer post brachytherapy-induced progression. In patients with distal ureteral stones, silodosin treatment is beneficial in decreasing stone expulsion time without affecting stone expulsion rate or analgesic need. Moreover, there were significant improvements in intravaginal ejaculation latency time, quality of life scores, and decrease in PE profile among patients with PE. Silodosin has also demonstrated promising results in increasing the likelihood of successful trial without catheter in patients with AUR and those taking antihypertensive drugs. Reports from Phase II studies have shown promising role of silodosin in the treatment of CP/CPPS as well as facilitating ureteral stone passage. From the robust data in this review, further silodosin treatment strategies in the management of different urological conditions need to be focused on.

Alpha-blockers for the Treatment of Benign Prostatic Hyperplasia

Over the last 2 decades the evolution of alpha-blockers for lower urinary tract symptoms (LUTS)/benign prostatic hyperplasia (BPH) has been to preserve effectiveness, improve tolerability, and eliminate dose titration. Today, alpha-blockers represent the first-line treatment of most men with BPH whereby the primary objective is relief from bothersome LUTS.

Non-Hormonal treatment of BPH/BOO

OBJECTIVES

To review the use of non-hormonal pharmacotherapies in the treatment of lower urinary tract symptoms (LUTS) due to presumed benign prostatic hyperplasia (BPH).

MATERIALS AND METHODS

A search of the PUBMED database was conducted for the terms BPH, LUTS, bladder outlet obstruction, alpha-adrenoceptor blockers, anti-muscarinics, and phosphodiesterase-5-inhibitors.

RESULTS

Medical therapy has long been established as the accepted standard of care in the treatment of male LUTS. The aim of treatment is improvement in symptoms and quality of life whilst minimizing adverse effects. The agents most widely used as 1(st) line therapy are alpha-blockers (AB), as a standalone or in combination with 2 other classes of drug; 5-α reductase inhibitors and anti-muscarinics. AB have rapid efficacy, improving symptoms and flow rate in a matter of days, these effects are then maintained over time. AB do not impact on prostate size and do not prevent acute urinary retention or the need for surgery. Anti-mucarinics, alone or in combination with an AB are safe and efficacious in the treatment of bothersome storage symptoms associated with LUTS/BPH. Phosphodiesterase-5 inhibitors are an emerging treatment option that improve LUTS without improving flow rates.

CONCLUSIONS

AB are the most well-established pharmacotherapy in the management of men with LUTS/BPH. The emergence of different classes of agent offers the opportunity to target underlying pathophysiologies driving symptoms and better individualize treatment.

Advances in the design and discovery of drugs for the treatment of prostatic hyperplasia

INTRODUCTION

Benign prostatic hyperplasia (BPH) is a common medical problem in nearly 80% of geriatric male population severely affecting the quality of life. Several strategies has been suggested in the past for the management of BPH, but only α-blockers and 5α-reductase inhibitors are in clinical use. This review aims to give deep insight into advances in the design and discovery of newer chemical entities as 'druggable' molecule for the management of BPH.

AREAS COVERED

In this review, the authors cover various classes of drugs that have shown their potential for management of BPH. These drugs include α-adrenergic antagonists, 5α-reductase inhibitors, phytochemical agents, phosphodiesterase inhibitor, luteinizing hormone releasing hormone antagonists and muscarinic receptor antagonists. Literature searches were carried out using Google Scholar, SciFinder and PubMed.

EXPERT OPINION

The exact etiology of BPH is unknown; however, several mechanisms may be involved in the progression of the disease. Beside surgery and watchful waiting, medical therapies to treat BPH include α-adrenergic antagonist and 5α-reductase inhibitors. Phytotherapeutic agents are also used in some countries. Various other chemical classes of drugs are proposed for the treatment of the disease, but none of them have reached the clinic. Many classes of drugs are currently undergoing clinical trials such as phosphodiesterase inhibitors, luteinizing hormone releasing hormone antagonists and muscarinic receptor antagonists. The current need is to develop a potent, efficacious and highly selective drug for the treatment of BPH.

α-Blockers for benign prostatic hyperplasia: the new era

PURPOSE OF REVIEW

α1-Adrenoceptor blockers are the most frequently prescribed medical therapy in the treatment of lower urinary tract symptom suggestive of benign prostatic hyperplasia (LUTS/BPH). The purpose of this review is to highlight the evolution of adrenoceptor blockers with emphasis on newly approved drugs.

RECENT FINDINGS

Over the past years new formulations of several α1-adrenoceptor blockers were introduced to the market. Five long-acting α1-blockers are currently approved by the Food and Drug Administration for treatment of symptomatic LUTS/BPH: terazosin, doxazosin, tamsulosin, alfuzosin and silodosin. Silodosin is the only adrenoceptor blocker that exhibits true selectivity for the α1-adrenoceptor subtypes. This unique adrenoceptor selectivity profile likely accounts for the very favorable cardiovascular safety profile.

SUMMARY

Tamsulosin, alfuzosin slow release and silodosin do not require dose titration. Alfuzosin, terazosin, doxazosin and silodosin have all been shown to be effective in relieving LUTS/BPH independent of prostate size. Low incidence of orthostatic hypotension has been reported for silodosin, but abnormal ejaculation is the most commonly reported adverse effect.

The role of nocturia in the quality of life of men with lower urinary tract symptoms

OBJECTIVES

To determine the role of treatment-associated improvement in nocturia in health-related quality of life (HRQL) in patients with lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia, and secondarily to confirm the role of nocturia in HRQL at baseline and to compare the effects of watchful waiting, transurethral microwave treatment (TUMT) and transurethral resection of the prostate (TURP) to those of α1-adrenoceptor antagonists (α-blockers) on nocturia.

PATIENTS AND METHODS

We retrospectively analysed using multiple regression a large single-centre database of patients receiving routine care for treatment-associated alterations of symptoms and HRQL (assessed at baseline, 2611 men) and 6-12 months after initiation of treatment (1258 men).

RESULTS

Among the symptoms assessed using the International Prostate Symptom Score, nocturia (together with urgency and weak stream) had the strongest correlation with HRQL at baseline and after treatment. Watchful waiting, α-blockers, TUMT and TURP reduced nocturia episodes by a mean (sd) of 7 (53)%, 17 (40)%, 32 (47)% and 75 (23)%, respectively. The treatment-associated improvements in nocturia (together with those of weak stream) had the strongest association with those of HRQL.

CONCLUSIONS

We conclude that among all LUTS assessed in the IPSS, nocturia has one of the strongest associations with HRQL, and that treatment-associated improvements in nocturia contribute considerably to overall improvements in HRQL.

Behaviour modification and benign prostatic hyperplasia: replacement for medications

PURPOSE OF REVIEW

Lower urinary tract symptoms due to benign prostatic hyperplasia (BPH) is a highly prevalent chronic disease. The cost impact of treatment is high. The field of behavioural treatments which could be suitable in the majority of uncomplicated patients has rarely been assessed. We summarize the recent knowledge and data from behavioural interventions chiefly the randomized controlled trial (RCT) of a self-management programme for BPH.

RECENT FINDINGS

The self-management RCT has revealed that a rigorously structured behavioural programme can significantly reduce lower urinary tract symptoms severity and decrease objective symptoms like nocturia, urgency and frequency compared with standard care alone. The elements of the programme and their behavioural framework are carefully defined. The basis of the programme's effectiveness is yet unknown, but may involve changes in bladder capacity rather than simple fluid management. The sphere of behavioural interventions for BPH is lacking and requires more research.

SUMMARY

Elements of the self-management programme are already being used in watchful waiting. Improving quality of life of patients with BPH through self-management will help patients and may reduce the financial burden on healthcare systems. The promotion of multidisciplinary team is a key step in implementing self-management strategies. With larger scale trials, the limitations raised and questions posed by the RCT can be further addressed.

Tamsulosin versus terazosin for benign prostatic hyperplasia: a systematic review

The effectiveness and safety of tamsulosin and terazosin for patients with benign prostatic hyperplasia (BPH) was evaluated by literature review. PubMed, Embase, the Cochrane Library, Chinese biomedicine literature database (CBM), reference lists of reports, and reviews were searched for randomized controlled trials (RCTs), or quasi-RCTs of tamsulosin versus terazosin in BPH. Twelve studies involving 2,816 men were included. Outcomes included international prostate symptom score (IPSS), quality of life (QOL), maximum urinary flow rate (Q(max)), average urinary flow rate (Q(ave)), residual volume, prostate volume, and adverse effect (dizziness, severe hypotension, dry mouth). Relative risk was calculated for dichotomous data. Sensitivity analyses assessed the influence of baseline symptom severity. We found that tamsulosin is better than terazosin when assessed by IPSS (weighted mean difference (WMD)=-1.24 95% CI [- 1.98, -0.51], there was no significant difference between the two groups in QOL (WMD=0.04 95% CI [-0.16, 0.24]), Qmax (WMD=-0.38 95% CI [-1.18, 0.41]), Q(ave) (WMD=-0.39 95% CI [- 0.84, 0.06]), residual volume (WMD=-4.32 95% CI [-10.96, 2.33]), and prostate volume (WMD=-0.28 95% CI [- 3.37, 2.81]). Fewer patients receiving tamsulosin experienced dizziness (relative risk (RR) -0.38 95% CI [0.30, 0.48]), severe hypotension (RR=0.16 95% CI [0.04, 0.68]), and dry mouth (RR=0.14 95% CI [0.03, 0.77]), compared with patients receiving terazosin. Many of the high quality RCTs showed beneficial effects of tamsulosin in terms of improving IPSS. However, whether tamsulosin proves more efficacious than terazosin in long term therapy requires confirmation by additional large sample, high quality trials.

Drug treatment of urological symptoms: estimating the magnitude of unmet need in a community-based sample

OBJECTIVE

To examine, in a community-based sample, the use of prescription drugs for lower urinary tract symptoms/benign prostatic hyperplasia (LUTS/BPH), overactive bladder, erectile dysfunction, urinary incontinence, and painful bladder syndrome; and to determine whether the use of recommended medications varied by sociodemographics, symptom severity, access to care, and other factors.

SUBJECTS AND METHODS

In a cross-sectional analysis of data obtained from 5503 men and women residents participating in the Boston Area Community Health Survey of Boston, MA, urological symptoms were ascertained by in-person interviews conducted during 2002-2005, using validated symptom scales. Medication use in the past 4 weeks was captured using a combination of drug-inventory methods and self-report.

RESULTS

Compared to the prevalence of symptoms, the prevalence of use of medications for urological conditions was very low among men and women. The highest prevalence of use was among men with moderate-to-severe LUTS/BPH symptoms, where 9.6% used recommended drugs. Use of medications did not vary consistently by race/ethnicity or socioeconomic status, but was often associated with symptom severity. More frequent and more recent use of medical care was also associated with greater use of urological medications.

CONCLUSIONS

Only a small proportion of community-dwelling men and women with urological symptoms are receiving recommended effective drug treatments for urological conditions. While not all persons are candidates for drug treatment, our results suggest that there is a substantial unmet need in the general population.

Emerging drug therapies for benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is the nonmalignant enlargement of the prostate gland caused by increases in number of both epithelial and stromal cells. Clinically, BPH leads to voiding dysfunction, which is most often referred to as lower urinary tract symptoms (LUTS). Historically, the only treatments for LUTS due to BPH were watchful waiting or surgery (transurethral or open prostatectomy). However, over the last 20 years medical therapy has taken a prominent role in the management of BPH. Current medical treatments for BPH include alpha-adrenergic receptor antagonists, inhibitors of the 5-alpha reductase enzyme and various phytotherapies. These agents are generally effective and safe; however, many patients are unable to tolerate the side effects or are refractory to medical management and require surgery. In light of this, many potential new therapies for the treatment of BPH are under development. Some represent a variation of current treatments, whereas others target novel molecular pathways within the prostate. The aim of this review is to examine current pharmacotherapies as well as to highlight emerging drugs that may improve our treatment of patients with LUTS secondary to BPH.

Management of Benign Prostate Hyperplasia: An Overview of α-Adrenergic Antagonist

Benign prostate hyperplasia (BPH) is common among above 50 years age group, interfere with normal activities of lower urinary tract function and reduce the sense of well being. It can also be progressive, with a lost of urinary retention, bladder infection, bladder calculus and renal failure. Although many men with mild to moderate symptoms to well without therapy, others have gradually increasing symptoms and require medical therapy or surgery. BPH is the non-malignant, uncontrolled growth of cells in the prostate gland. This cell growth usually occurs in the tissue that surrounds the urethra as it passes through the prostate gland to the bladder. As BPH progresses, the gland constricts the urethra and obstructs the urine outflow. The bladder no longer empties completely, creating an environment in which infections, bladder stones, and chronic prostatities may develop. If left untreated, chronic obstruction can lead to the back up of urine into the ureters and compromise kidney function. In hyperplastic prostate tissue, the prostate capsule, and the bladder neck are blocked, by using alpha-adrenergic antagonist drugs; the smooth muscle tone of these structures is decreased. As a result, resistance to urinary flow through the bladder neck and the prostatic urethra decreases and urinary flow increases. A variety of alpha-adrenergic antagonists with distinct properties have been investigated as possible treatments for benign prostate hyperplasia.

alpha1-Adrenoceptor subtype selectivity and lower urinary tract symptoms

Benign prostatic hyperplasia is a common cause of urinary flow obstruction in aging men and may lead to lower urinary tract symptoms (LUTS). Benign prostatic hyperplasia has 2 physiological components: a static component related to increased prostate size and a dynamic component related to increased prostate smooth muscle tone. alpha1-Adrenoceptors (alpha1ARs) maintain prostate smooth muscle tone; hence, alpha1-antagonists (blockers) relax prostate smooth muscle and decrease urethral resistance, ultimately leading to relief of LUTS. This review focuses on alpha1AR subtypes and their location in lower urinary tract tissues involved in LUTS (prostate, bladder, spinal cord); it also summarizes major clinical trials published to date on the efficacy of alpha1AR blockers for LUTS. Benefits and adverse effects of clinically available alpha1AR antagonists are reviewed, followed by recent information on interactions between alpha1AR subtype antagonists and type 5 phosphodiesterase inhibitors used for impotence. alpha1-Adrenoceptor antagonists have become the mainstay of therapy for LUTS; knowledge about specific alpha1AR subtypes should facilitate rational choice of alpha1AR blocker therapy by clinicians.

Pharmacological characterization of isolated human prostate

PURPOSE

Human prostate contains alpha-1 adrenergic, cholinergic and nonadrenergic noncholinergic neuroreceptors. Using agonistic and antagonistic agents at these neuroreceptors we studied the resultant contractile responses in isolated human prostate.

MATERIALS AND METHODS

Human prostate tissue was obtained at prostatectomy for benign prostatic hyperplasia in 37 adult male patients. Tissues were suspended in tissue bath chambers connected to force displacement transducers. Specimens were subjected to agonist induced contractions, the first always being norepinephrine (NE). Specimens were pretreated with antagonist (adrenergic, cholinergic, nonadrenergic noncholinergic or none if control), followed by contraction with a second agonist (NE or other). Contractile tensions were recorded on a polygraph and then statistically analyzed.

RESULTS

The order of highest to lowest agonist induced tensile forces was NE, dopamine, acetylcholine, bethanechol, histamine and serotonin. Excitatory concentration EC(50) values were determined for each agonist tested. Significant differences were found between specific alpha-1 adrenergic receptor blockers (terazosin, prazosin and the experimental drug LY253352). In addition, many other agents antagonized the alpha-1 adrenergic receptor. Inhibitory concentration IC(50) values were obtained and the order of alpha-1 adrenergic antagonistic strengths from strongest to weakest was LY253352, prazosin, terazosin, ketanserin, SCH23390, diphenhydramine, DO710, dopamine, serotonin and histamine.

CONCLUSIONS

Human prostate neuroreceptors were determined to be alpha-1 adrenergic, dopaminergic, muscarinic cholinergic, 2A serotonergic and H1 histaminergic. Dopamine, serotonin, histamine and their antagonists blocked the adrenergic response, indicating possible receptor-receptor interaction. Further study of the pharmacology of human prostate would likely identify new drugs for treating patients with bladder outlet obstruction due to benign prostatic hyperplasia.

Early treatment of benign prostatic hyperplasia: implications for reducing the risk of permanent bladder damage

A significant change has occurred in the management of symptomatic benign prostatic hyperplasia (BPH) since effective pharmacological treatment became available and led to a significant decrease in the number of surgical procedures in many Western countries. The hypothesis of a causative role of benign prostatic enlargement and bladder outflow obstruction (BOO) in lower urinary tract symptoms (LUTS) was based on the association between prostate growth and symptoms of prostatism in elderly men and on the dramatic reduction of LUTS upon relief of obstruction. Careful investigation into the epidemiology of LUTS and BPH failed to confirm such an association and opened new perspectives in the pathophysiology of lower urinary tract dysfunction and symptoms. The observation that LUTS were equally distributed in male and female cohorts, when matched for age, moved attention away from the prostate and towards the urinary bladder and its aging-related disorders. When BPH surgery was developed, the management of the disease was aimed at preventing death from chronic renal failure, but the picture has changed and modern medical treatment is now aimed at improving the patient's quality of life. The increasing size of elderly populations in the Western world and the consequent financial constraints of national healthcare systems have raised the question of when pharmacological treatment of symptomatic BPH should be initiated. Retrospective and prospective analysis of various BPH populations and clinical studies has clearly defined the capacity of pharmacological treatment to reduce the incidence of complications of BPH, such as acute urinary retention and the need for surgery, but the cost/benefit ratio is unclear. Notwithstanding the limitations inherent in the experimental models, there is evidence from various animal models, investigating the pathophysiology of the urinary bladder in the presence of outflow obstruction, to indicate that a cause and effect relationship between BOO and bladder decompensation has been established and to support the hypothesis that permanent bladder damage may occur when the obstruction is not relieved early enough. Preliminary experimental evidence also suggests that alpha(1)-adrenoceptor antagonists may have a role in reducing the damaging effects of BOO on the urinary bladder. At present, there is no evidence to support the need for early pharmacological treatment of symptomatic BPH with no BOO beyond the obvious target of improving the patient's quality of life. The evidence for early treatment of BOO and the need to preserve bladder function is clear. Further experimental and clinical research is required to identify markers of early bladder damage and decompensation which can be used to select patients for early pharmacological treatment of BPH.

Study design of the Medical Therapy of Prostatic Symptoms (MTOPS) trial

Alpha-blockers and 5-alpha-reductase inhibitors are medical therapies that are being used as alternatives to surgical interventions to relieve symptoms of benign prostatic hyperplasia (BPH). Taken as monotherapy, alpha-blockers and 5-alpha-reductase inhibitors have each been shown to provide relief from BPH symptoms. Treatment with finasteride over 4 years has been shown to reduce both BPH symptoms and the likelihood of acute urinary retention and the need for surgery. Direct comparison of the alpha-blocker terazosin with finasteride has been done, but only for a period of 1 year. The Medical Therapy of Prostatic Symptoms (MTOPS) trial is a multicenter, randomized, placebo-controlled, double-masked clinical trial designed to evaluate the long-term efficacy of the alpha-blocker doxazosin and the 5-alpha-reductase inhibitor finasteride, whether taken as a monotherapy or in combination, in preventing or delaying the progression of BPH. We describe in this paper the design of the MTOPS trial, the concept of BPH progression, the definition and methods of determining the primary outcome events and the proposed statistical analysis methods. A unique feature of MTOPS is the inclusion of prostate biopsies on a subgroup of randomized participants. Volunteers among randomized participants are to undergo a biopsy of the prostate at predetermined time points during the trial. Studies that will be conducted using the tissue specimens collected in MTOPS can potentially provide information at the molecular level on the natural history of BPH among medically treated and untreated men with moderate to severe symptoms of BPH.

Current concepts in the pharmacotherapy of benign prostatic hyperplasia

Benign prostatic hyperplasia is a major men's health issue, with approximately 80% of all men developing this condition within their lifetime. A variety of oral treatments is available, including alpha-adrenoceptor antagonists (alpha-blockers), 5alpha reductase inhibitors, aromatase inhibitors and phytotherapy. A large number of alpha-blockers can be administered, but no single agent has demonstrated a clear superiority over the other drugs. 5alpha Reductase inhibitors have demonstrated similar efficacy in larger volume prostates but most evidence suggests that there is no benefit in combining them with alpha-blockers. The use of phytotherapy is not entirely novel but requires further long-term evaluation before it can be endorsed for clinical use in benign prostatic hyperplasia.

Overactive bladder in the male patient: bladder, outlet, or both?

Generations of urologists have presumed that the cause of lower urinary tract symptoms (LUTS) in men is infravesical (prostatic) obstruction. When symptoms such as urinary urgency and frequency can't easily be explained directly by obstruction, secondary effects of obstruction on the bladder are identified as causative factors. Although to some extent this explanation may still be accurate, emerging concepts in the pathophysiology of LUTS in men may be at odds with these traditional explanations. The idea that primary bladder pathology may explain the symptom complex in at least one subset of men with LUTS has both experimental and clinical support. This review discusses the physiologic and clinical observations used to explain the mechanisms underlying LUTS. Specifically, this review focuses on two data sets: one supporting infravesical obstruction as the causative factor for LUTS, and another positing that a primary bladder abnormality is responsible.

Terazosin, doxazosin, and prazosin: current clinical experience

Lower urinary tract symptoms (LUTS) suggestive of benign prostatic obstruction are common in aging men. Nearly 25% of men >40 years of age have LUTS. Medical therapy with alpha-blockade is the most common method of medical therapy for benign prostatic obstruction. Multiple methods of minimally invasive surgical therapies have been introduced in the last decade. These methods include balloon dilatation, temporary and permanent urethral stents, various laser techniques, microwave thermotherapy, transurethral needle ablation, electrovaporization, and high-intensity focused ultrasound. alpha-Receptor blockers to reduce the sympathetic tone of the prostate are considered as first-line therapy to relieve the symptoms of benign prostatic hyperplasia. Selective alpha(1)-receptor blockers relax prostatic smooth muscle, relieve bladder outlet obstruction, and enhance urine flow with fewer side effects. In addition, it was determined that treating patients with alpha-blockers increases prostatic apoptosis. Pharmacokinetic activity, mode of action, clinical efficacy, and side effects of the selective alpha(1)-receptor blockers terazosin, doxazosin, and prazosin are reviewed.

Variability of pressure-flow studies in men with lower urinary tract symptoms

The objective of this study was to assess the short-term test-retest variability of pressure-flow studies (PFS) in men with lower urinary tract symptoms (LUTS). By choosing a short interval between two consecutive PFS, but notably not performing two tests within a single session, both tests represent the same routine testing procedure. Eighty-nine patients with LUTS suggestive of bladder outlet obstruction or detrusor underactivity, who received PFS, were asked to undergo a second urodynamic evaluation within 4 weeks after the initial test. At both visits, specialized physicians performed the PFS. Obstruction was quantified using the Abrams-Griffiths number (AG number). Each patient was classified as obstructed, unobstructed, or equivocally obstructed according to the International Continence Society nomogram. As expected, no systematic difference was observed in AG number between the first and the second visit at the group level. There was, however, considerable variation at the individual level. The average within-patient standard deviation was 14 cm H(2)O. This finding shows that if a patient's AG number is 30 at the first visit, his true AG number can be any value between 30 +/- 1.96 * 14 = 3 to 57, owing to random variability alone. The average within-patient standard deviation did not differ significantly between sub-groups of obstruction and other variables such as patient age, symptom score, prostate volume, or residual volume. The variability appeared to increase slightly with an increased interval between visits. Of all patients, 39% changed at least one category of obstruction at the second visit and 3% changed from definitely obstructed to definitely unobstructed or vice versa. We conclude that PFS cannot stand the test of serving as a gold standard to identify bladder outlet obstruction in patients with LUTS.

Alpha adrenoceptor antagonists in the year 2000: is there anything new?

Selective alpha1-adrenergic blockade is now a well accepted and widely used therapeutic treatment for patients presenting with symptomatic bladder outlet obstruction thought to be associated with benign prostatic hyperplasia. This review summarizes the recent developments in this field relating to the subject of receptor subtype selectivity and the potential relevance of this to clinical usefulness of existing drug therapy. Whilst a number of unanswered questions remain as to the exact mechanisms of both drug action and side-effect profile, nevertheless it is clear that existing clinically available alpha1-antagonists provide a safe, effective and generally well tolerated therapy for patients with lower urinary tract symptoms thought to be associated with benign prostatic obstruction. The implications of the ALLHAT study are discussed.

The clinical role of alpha-blockers in the treatment of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a highly prevalent condition that represents a significant health problem, which is likely to worsen as the population continues to age. alpha-1 adrenoceptor antagonists have been used in the treatment of this condition for well over 20 years and much is now known about their effects on the urinary tract. As these drugs have improved, their use as a first line treatment option in patients with lower urinary tract symptoms (LUTS), secondary to BPH, has continued to increase. This review details some of the background and rationale for the use of these drugs and, using the available information, compares their efficacy and tolerability profiles.

A comparative study of terazosin and tamsulosin for symptomatic benign prostatic hyperplasia in Japanese patients

OBJECTIVE

To compare the efficacy and safety of an incremental-dose regimen of terazosin (1-2 mg daily) and a fixed-dose regimen of tamsulosin (0.2 mg daily), on Japanese patients with symptomatic benign prostatic hyperplasia (BPH).

PATIENTS AND METHODS

This multicentre, single-blind, randomized trial compared terazosin and tamsulosin over 4 weeks, in 61 patients with symptomatic BPH randomly assigned to terazosin (n = 31) or tamsulosin (n = 30). Terazosin 0.5 mg twice daily was administered for 2 weeks, followed by 1 mg twice daily for 2 weeks. Tamsulosin (0.2 mg) was administered once daily for 4 weeks. Symptoms were evaluated using the International Prostate Symptom Score (IPSS), and quality of life (QOL) was assessed subjectively before treatment, and again after 2 and 4 weeks of treatment. Objective measurements taken before and after the treatment period were the maximum (Qmax) and average (Qave) urinary flow rates, and the percentage residual urine volume. Improvement was defined as a 25% decrease from baseline in IPSS, > 1 point increase in QOL score, and > 2.5 mL/s increase in Qmax. Adverse reactions potentially related to the study drugs were recorded throughout the treatment period.

RESULTS

Both terazosin and tamsulosin produced statistically significant improvements in subjective and objective variables. Neither treatment affected systolic or diastolic blood pressure or pulse rate. Adverse reactions were noted in four patients (three in the terazosin group and one in the tamsulosin group). However, there was no statistically significant difference in the incidence of adverse effects between the groups.

CONCLUSIONS

Despite the limitations of small sample size and relatively short treatment periods, terazosin and tamsulosin were equally effective in the treatment of symptomatic BPH in Japanese patients, using relatively lower doses than those used in Western countries.

Effects of doxazosin in men with benign prostatic hyperplasia: urodynamic assessment

OBJECTIVE

In this study, a randomized and placebo controlled trial, we aimed to study the effectiveness and safety of doxazosin based upon urodynamic parameters, especially pressure/flow studies, in men with benign prostatic hyperplasia (BPH).

MATERIALS AND METHODS

A total of 57 men (29 doxazosin, 28 placebo) 48-82 years of age with BPH were enrolled. Yet, 8 of 29 in the doxazosin group and 10 of 28 in the placebo group were excluded due to side effects of doxazosin and intolerability of urodynamic assessment of free uroflow, postvoiding residual urine volume (PVR) and pressure/flow studies.

RESULTS

There were improvements in all urodynamic parameters (Free Qmax: 30.4% and 28%, PVR: 14 ml and 12 ml, invasive Qmax: 29.3% and 26.2%, Pdet at Qmax: -32.7% and -30%, Pdet-max: -29% and -27.7% at end of the 1st and 6th months whereas placebo effects were worsening in all urodynamic parameters.

CONCLUSIONS

We suggest that doxazosin is an important treatment option for patients with BPH, and efficacy of doxazosin should be evaluated with objective, quantitative urodynamic studies not with subjective symptom scores. But additional costs and invasiveness of urodynamic studies restrict their common usefulness.

[Prostatic benign hypertrophy: review of effectiveness, tolerance, and impact on quality of life of prolonged treatment with alfuzosin]

OBJECTIVES

To evaluate the effectiveness of Alfuzosin in terms of long term effect in BHP patients. To analyze the effectiveness according to the observer, the treatment compliance and the tolerance of alfuzosin, and specifically, cardiovascular and sexually adverse events. Also, to define the clinical profile of the BPH patients that spontaneously seek medical treatment in Spain.

DESIGN OF THE STUDY

Observational, descriptive, multicentric and 6-month retrospective study. DATA SOURCES AND COLLECTION: From the patient reports of BPH patients treated with alfuzosin during more than 6 months, data gathered were, along with usually anamnesic data and physical exploration (age, symptoms, blood pressure, e.g.), those related to treatment response, effectiveness, compliance and tolerance of Alfuzosin in the first and second quarter. Data of the 1635 patients initially recruited were considered to define the clinical profile of this population. Effectiveness and tolerance analysis were undertaken with the 911 patients who followed the treatment during the 6-month study.

RESULTS

After 6 months of treatment an improvement of the mean intensity of each of the urinary symptoms were statistically significant (p < 0.005). Also, the mean score of each of the analyzed variables and of the I-PSS global score were reduced significantly (p < 0.005). After 6 months of treatment the effectiveness evaluated by the observer was good or very good for the 88.5% of the patients. Treatment compliance was very good; from the 911 patients finishing the study, 96.4% continued with the initially prescribed treatment. Just 16 patients (3%) developed adverse events; measures undertaken were to modify the dosage or to interrupt the treatment (2 cases). The specific study of cardiovascular adverse events showed a mild reduction in the systolic (142 mmHg versus 137.86 mmHg) and diastolic blood pressure (83.53 mmHg) versus 80.72 mmHg), and the heart rate (76.80 l/m versus 76.04 l/m). The mean score of sexual life showed an improvement in all the items studied, although very slight.

CONCLUSIONS

The usefulness, effectiveness and tolerance of a long term treatment with alfuzosin in HPB patients was confirmed. Alfuzosin is considered a first choice treatment in patients with the clinical profile described.

Subtype selective alpha1-adrenoceptor antagonists for the treatment of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is highly prevalent in the male population beyond the age of 60. Impairment of urinary flow due to prostate enlargement gives rise to symptoms of 'prostatism' that have a detrimental impact on the quality of life. The current trend in the management of symptomatic BPH favours pharmacotherapy as a first line option, while the number of surgical procedures being performed has experienced a steady decline during the last ten years. Among the pharmacological treatments, the use of alpha1-adrenoceptor blockers has demonstrated to be an effective treatment option for BPH. These agents reduce the adrenergic tone to the prostate and increase urinary flow, with a concomitant reduction of lower urinary tract symptoms. The alpha1-blockers currently approved include compounds such as alfuzosin, terazosin and doxazosin, originally developed for the treatment of hypertension, and more recently tamsulosin, an alpha1-subtype selective drug. The blockade of alpha1-adrenoceptors present in vascular smooth muscle is largely responsible for the most prominent side effects of current drugs, which can be severe and require patients dose titration. The limitation imposed by side effects naturally raises the possibility that complete blockade of prostatic alpha1 receptors is not attained at the maximum tolerated dose. The extensive efforts by the pharmaceutical industry towards the development of uroselective alpha1-blockers, is the subject of this review. Advances in the molecular cloning of genes encoding three alpha1-adrenoceptors led to the identification of the alpha1A-subtype as the predominant receptor responsible for the contraction of prostate smooth muscle. In preclinical animal models, selective alpha1A-antagonists have consistently been found to have minimal cardiovascular effects, thus providing a pharmacological rationale for uroselectivity. It has also become apparent, however, that uroselectivity can emerge in a poorly understood manner from the pharmacodynamic properties of compounds without alpha1A-subtype selectivity. Clinical experience with tamsulosin, an alpha1A/alpha1D selective drug, has failed to demonstrate a significant improvement in efficacy beyond that demonstrated for non-subtype selective alpha1-blockers, and gives support to the notion that alpha1A-selective antagonists might achieve greater efficacy for the treatment of BPH. Given the demonstrated uroselectivity of alpha1A-selective antagonists in preclinical models, it is anticipated that third generation alpha1-blockers will exhibit improved urinary flow efficacy and be better tolerated than tamsulosin. The extent to which the improvement in urinary flow will translate to the relief of symptoms of prostatism, however, remains to be demonstrated in randomised placebo-controlled clinical trials of alpha1A-selective antagonists.

Naftopidil, a novel alpha1-adrenoceptor antagonist, displays selective inhibition of canine prostatic pressure and high affinity binding to cloned human alpha1-adrenoceptors

The pharmacological profiles of the alpha1-adrenoceptor antagonists naftopidil, tamsulosin and prazosin were studied in an anesthetized dog model that allowed the simultaneous assessment of their antagonist potency against phenylephrine-mediated increases in prostatic pressure and mean blood pressure. The intravenous administration of each of these compounds dose-dependently inhibited phenylephrine-induced increases in prostatic pressure and mean blood pressure. To further assess the ability of the three compounds to inhibit phenylephrine-induced responses, the doses required to produce a 50% inhibition of the phenylephrine-induced increases in prostatic and mean blood pressure and the selectivity index obtained from the ratio of those two doses were determined for each test compound. Forty minutes after the intravenous administration of naftopidil, the selectivity index was 3.76, and those of tamsulosin and prazosin were 1.23 and 0.61, respectively. These findings demonstrated that naftopidil selectively inhibited the phenylephrine-induced increase in prostatic pressure compared with mean blood pressure in the anesthetized dog model. The selectivity of naftopidil for prostatic pressure was the most potent among the test compounds. In addition, using cloned human alpha1-adrenoceptor subtypes, naftopidil was selective for the alpha1d-adrenoceptor with approximately 3- and 17-fold higher affinity than for the alpha1a- and alpha1b-adrenoceptor subtypes, respectively. The selectivity of naftopidil for prostatic pressure may be attributable to its high binding affinity for alpha1a- and alpha1d-adrenoceptor subtypes.

Alpha-adrenergic blocking drugs in the management of benign prostatic hyperplasia: interactions with antihypertensive therapy

Management of benign prostatic hyperplasia (BPH) is often complicated by concomitant hypertension, a life-threatening condition that must be managed optimally. Many of the alpha blockers used to treat BPH also decrease blood pressure, and terazosin and doxazosin have been shown to have significant cardiovascular side effects, such as asthenia/fatigue, postural hypotension, and dizziness when used to treat BPH patients. Furthermore, these drugs are not first-line therapies for hypertension, and the majority of hypertensive BPH patients will be receiving other antihypertensive agents. Therefore, it is possible that the introduction of these drugs will affect blood pressure control, at least temporarily, with possible adverse effects. In contrast, the selective alpha1A blocker tamsulosin does not appear to have significant cardiovascular side effects and produces minimal blood pressure reductions. Therefore, urologists can choose either to use alpha blockers to treat both hypertension and BPH or to treat BPH using alpha blockers that do not interact with antihypertensive therapy. This review focuses on the alpha blockers currently being used to treat BPH, their effects on the cardiovascular system, and their interaction with antihypertensive drugs.

Prevention of Postherniorrhaphy Urinary Retention with Prazosin

Urinary retention that necessitates catheterization after herniorrhaphy is a well known, but usually ignored, situation. Increased sympathetic activity resulting from surgery may be the contributing factor. Blockade of a receptors in the bladder neck and urethral sphinchter may prevent postoperative urinary retention. In this prospective placebo-controlled study, the efficacy of prazosin in preventing postoperative urinary retention after herniorrhaphy was investigated in 156 patients. Patients were randomized into two groups. Patients in Group I (control) were given placebo orally 12 hours before surgery, just before surgery, and 12 and 24 hours after surgery. In Group II, 1 mg of prazosin was given in the same manner of placebo. Nine of 84 patients (10.8%) in the prazosin group and 18 of 72 patients (25%) in the placebo group developed urinary retention. Catheterization was required in only 3 patients (3.5%) in the prazosin group compared to 10 patients (13.8%) in placebo-treated group (P < 0.05). In conclusion, prophylactic use of prazosin after herniorrhaphy significantly reduced the incidence of urinary retention and catheterization.

Sexual dysfunction in patients with benign prostatic hyperplasia

Two of the most common problems presenting to urologists are benign prostatic hyperplasia and sexual dysfunction, with an increasing number of patients presenting for treatment as a result of the proliferation of less invasive therapies. How such therapies for lower urinary tract symptoms affect sexual function in men is important to both urologists and their patients, and is the focus of this review.

Selective alpha-1a adrenergic receptor antagonists. Effects of pharmacophore regio- and stereochemistry on potency and selectivity

The anti-anxiety agent ipsapirone has been shown to have modest affinity for alpha-1 receptors. We disclose the discovery of potent alpha-1a receptor subtype selective antagonists based on the ipsapirone structure which possess selectivity versus the 5-HT receptors tested. These antagonists were obtained by tethering a saccharin ring to 4-phenyl-3-carboxyethyl piperidines. The design principles which led to this structural motif are discussed. The synthesis of key analogs, their SAR, as well as results of selected in vitro and in vivo studies are described.

Overview of alpha-blocker therapy for benign prostatic hyperplasia

Management of benign prostatic hyperplasia (BPH) is rapidly changing. Established surgical procedures are being replaced by minimally invasive modalities such as electrovaporization and transurethral needle ablation. Improved understanding of pathophysiology and developments in molecular biology has provided drugs for alleviating the symptoms of prostatic enlargement. Currently, medical therapy is the first-line treatment modality in the management of BPH. There are two types of medical treatment available: alpha-adrenoceptor-blockers and 5-alpha-reductase inhibitors. Alpha-blockers relieve the dynamic component of obstruction whereas 5-alpha-reductase inhibitors relieve the mechanical component of obstruction. At present, alpha-blockers are used most frequently. However, they do have significant cardiovascular side effects. More uroselective alpha-blockers have recently become available and may reduce the risk of cardiovascular side effects. This review summarizes relevant literature on the use of alpha-blockers in the treatment of BPH.

Urodynamic effects of various treatment modalities for benign prostatic hyperplasia

PURPOSE

I studied the effects of various treatments for benign prostatic hyperplasia on urethral resistance.

MATERIALS AND METHODS

I reviewed the literature on urodynamic effects of treatments for benign prostatic hyperplasia. Articles that reported pretreatment and posttreatment values of relevant urodynamic parameters were analyzed. Average before and after treatment values of maximum flow rate and detrusor pressure at maximal flow rate for every study were plotted on an Abrams-Griffiths nomogram and classified as obstructed, equivocal or nonobstructed. Average values of maximum flow rate and detrusor pressure at maximal flow rate were calculated for the total number of patients treated by a certain modality.

RESULTS

Based on this analysis, the rank order of urodynamic efficacy was that open prostatectomy is more effective in reducing urethral resistance than is transurethral prostatectomy. These treatments diminish obstruction better than laser treatment or transurethral incision of the prostate, which again are more effective than balloon dilation, alpha-blockers or transurethral microwave thermotherapy. Finally, androgen deprivation performs better than placebo treatment.

CONCLUSIONS

The rank order of urodynamic efficacy as determined in this analysis shows a high level of agreement with reported rank order of symptomatic efficacy of various modalities. After placebo treatment there is no significant change in urethral resistance. This finding indicates that pressure-flow studies are a sensitive way to compare active to placebo treatment and that pressure-flow studies have excellent long-term reproducibility.

Functional property, norepinephrine content and morphometric findings in human hyperplastic prostate

BACKGROUND

Although alpha-adrenergic blockers are widely used as a treatment of benign prostatic hyperplasia (BPH), it is not clear whether contractile property of hyperplastic prostate to alpha-adrenergic agonist depends upon an area of density of smooth muscle within the respective BPH tissue.

METHODS

Functional study and quantitative morphometric analysis were performed on human prostatic specimens obtained by transurethral resection from 22 men with symptomatic BPH. Tissue norepinephrine content was also evaluated.

RESULTS

There was a linear correlation between the area of density of smooth muscle and maximum response to phenylephrine (r = 0.457, P = 0.0362). Although the area of density of smooth muscle showed a positive correlation with norepinephrine content (r = 0.437, P = 0.0471), norepinephrine content was not correlated with maximum phenylephrine response.

CONCLUSIONS

Contractile response to alpha-adrenergic agonist was directly influenced by the area of density of the smooth muscle within an individual prostate.

Clinical Experiment Comparing 3 Pharmacological Treatments of Benign Prostatic Hypertrophy: Terazosin Vs. Finasteride Vs. Terazosin + Finasteride

The tone of the smooth prostate muscle and the presence of hyperplastic tissue represent the dynamic and passive components respectively of the obstructive symptomatology present in benign prostatic hyperplasia (BPH). The contractile properties are mediated primarily by the alpha-1 type adrenergic receptors, which are found in great numbers in the stroma of the gland and in the prostatic capsule. The use of Terazosin, a selective alpha-1 blocker, has proved to be effective in the improvement of BPH symptoms associated with the hypertone of the smooth muscle. The assumption that androgens play an important role in hypertrophy of the prostate has introduced drugs into the treatment which are capable of blocking the synthesis and the action of testosterone and, in particular, dihydrotestosterone (DHT). Finasteride is an inhibitor of 5-alpha-reductase, the enzyme inside the prostatic epithelial cells which converts the testosterone into DHT. A multicentre study has therefore been carried out aimed at assessing, after 9 months treatment, the efficacy and tolerability of three pharmacological treatments: Terazosin, Finasteride and a combination of the two, in 146 patients with symptomatic BPH. Results of the study indicate that the drugs were well tolerated and that the efficacy in resolving the obstructive symptomatology was particularly accentuated and rapid in the groups treated with Terazosin, the action of which, in this respect, has proved to be more significant than that of Finasteride.

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.

Effect of the alpha-1 adrenoceptor blocker on tissue norepinephrine contents in human benign prostatic hyperplasia

To see the effect of the alpha-adrenergic blocking agent on tissue norepinephrine contents of the prostate, norepinephrine (NE) levels were investigated in patients with symptomatic benign prostatic hyperplasia (BPH). Morphometrical analyses were also performed to detect the differences in tissue composition. Nineteen patients were subdivided into two groups. Patients in Group 1 were given tamsulosin hydrochloride (0.2 mg/day) for at least 4 weeks before transurethral resection of the prostate (TURP), while patients in the control group (Group 2) underwent no previous treatment for BPH before TURP. Tissue NE contents were investigated by high performance liquid chromatography on a chip of the prostate obtained by TURP. These two groups were closely similar in age distribution, prostatic size, results of preoperative symptom scoring and relative proportion of smooth muscle component within the evaluated specimen. In the present series, tissue NE contents in these groups were not statistically different (p = 0.64). Chronic and acute administration of the alpha-1 antagonist did not apparently influence the tissue NE level in patients with BPH.