Pharmacological evidence of distinct alpha 1-adrenoceptor subtypes mediating the contraction of human prostatic urethra and peripheral artery

The Subtype Selectivity in Search of Potent Hypotensive Agents among 5,5-Dimethylhydantoin Derived α1-Adrenoceptors Antagonists

In order to find new hypotensive drugs possessing higher activity and better selectivity, a new series of fifteen 5,5-dimethylhydantoin derivatives (1-15) was designed. Three-step syntheses, consisting of N-alkylations using standard procedures as well as microwaves, were carried out. Crystal structures were determined for compounds 7-9. All of the synthesized 5,5-dimethylhydantoins were tested for their affinity to α1-adrenergic receptors (α1-AR) using both in vitro and in silico methods. Most of them displayed higher affinity (Ki < 127.9 nM) to α1-adrenoceptor than urapidil in radioligand binding assay. Docking to two subtypes of adrenergic receptors, α1A and α1B, was conducted. Selected compounds were tested for their activity towards two α1-AR subtypes. All of them showed intrinsic antagonistic activity. Moreover, for two compounds (1 and 5), which possess o-methoxyphenylpiperazine fragments, strong activity (IC50 < 100 nM) was observed. Some representatives (3 and 5), which contain alkyl linker, proved selectivity towards α1A-AR, while two compounds with 2-hydroxypropyl linker (11 and 13) to α1B-AR. Finally, hypotensive activity was examined in rats. The most active compound (5) proved not only a lower effective dose than urapidil but also a stronger effect than prazosin.

Comparative efficacy and safety profile of 4 vs 8 mg of silodosin once daily usage in patients with benign prostatic hyperplasia-related lower urinary tract symptoms divided into subgroups according to International Prostate Symptom Score severity

Background

The purpose of this study was to compare once daily (QD) usage of 4 and 8 mg of silodosin in patients divided as those with moderate and with severe lower urinary tract symptoms (LUTSs) according to International Prostate Symptom Score (IPSS) categories in terms of effectiveness and adverse events.

Methods

A total of 234 patients aged ≥ 40 years were evaluated prospectively. All participants were divided firstly into two groups according to their IPSS severity as moderate and severe. They were further allocated to receive 4 mg of silodosin and 8 mg of silodosin QD. Demographic features and laboratory tests were recorded. The patients were questioned with International Index of Erectile Function-5 and IPSS along with quality of life index. Uroflowmetric measurements were applied to the patients. All tests and measurements were repeated at the 3rd month, and changes from pretreatment to posttreatment were analyzed by SPSS 21.0 Program. The statistical significance level was set at p < 0.05.

Results

Both treatments provided benefit in patients with both moderate and severe LUTSs. While results did not differ among 4 mg and 8 mg of silodosin in patients with moderate LUTSs, 8 mg of silodosin was significantly better than 4mg in those with severe LUTSs in terms of improvement of the total IPSS, IPSS voiding subtotal score, and quality of life score (p = 0.015, 0.030, <0.001, respectively). Both treatments did not affect erectile functions. Adverse events were seen more frequently in patients receiving 8 mg of silodosin than those treated with 4 mg of silodosin (p = 0.024).

Conclusion

Our study revealed that 4 mg of silodosin QD was as effective as 8 mg of silodosin QD in patients with moderate LUTSs but not with severe LUTSs. It can be inferred from this study that prescription of 4 and 8 mg of silodosin may be chosen to treat the patients with moderate and severe LUTSs due to benign prostatic heperplasia, respectively.

Identification of 3,4-dihydro-2H-thiochromene 1,1-dioxide derivatives with a phenoxyethylamine group as highly potent and selective α1D adrenoceptor antagonists

A series of phenoxyethylamine derivatives was designed and synthesized to discover potent and selective human α_1D adrenoceptor (α_1D adrenergic receptor; α_1D-AR) antagonists. Compound 7 was taken from our internal compound collection as an attractive starting point and exhibited moderate binding affinity for α_1D-AR and high selectivity against α_1A- and α_1B-ARs. We focused on modifying the 2-methylsulfonylbenzyl group of 7 to discover novel compounds structurally distinct from other reported α₁-AR antagonists containing the phenoxyethylamine motif. Study of structure activity relationship guided by a targeted ligand-lipophilicity efficiency score led to the discovery of a novel scaffold of 3,4-dihydro-2H-thiochromene 1,1-dioxide for selective α_1D-AR antagonists. Further optimization studies resulted in the identification of (4S)-N⁴-[2-(2,5-difluorophenoxy)ethyl]-N⁶-methyl-3,4-dihydro-2H-thiochromene-4,6-diamine 1,1-dioxide, (S)-41, as a novel, highly potent and selective α_1D-AR antagonist. Herein, we provide details of the structure activity relationship of the phenoxyethylamine analog for the potency and selectivity.

Emerging and investigational drugs for premature ejaculation

Over the past 20−30 years, the premature ejaculation (PE) treatment paradigm, previously limited to behavioural psychotherapy, has expanded to include drug treatment. Pharmacotherapy for PE predominantly targets the multiple neurotransmitters and receptors involved in the control of ejaculation which include serotonin, dopamine, oxytocin, norepinephrine, gamma amino-butyric acid (GABA) and nitric oxide (NO). The objective of this article is to review emerging PE interventions contemporary data on the treatment of PE was reviewed and critiqued using the principles of evidence-based medicine. Multiple well-controlled evidence-based studies have demonstrated the efficacy and safety of selective serotonin reuptake inhibitors (SSRIs) in delaying ejaculation, confirming their role as first-line agents for the medical treatment of lifelong and acquired PE. Daily dosing of SSRIs is likely to be associated with superior fold increases in IELT compared to on-demand SSRIs. On-demand SSRIs are less effective but may fulfill the treatment goals of many patients. Integrated pharmacotherapy and CBT may achieve superior treatment outcomes in some patients. PDE-5 inhibitors alone or in combination with SSRIs should be limited to men with acquired PE secondary to co-morbid ED. New on-demand rapid acting SSRIs, oxytocin receptor antagonists, or single agents that target multiple receptors may form the foundation of more effective future on-demand medication. Current evidence confirms the efficacy and safety of dapoxetine, off-label SSRI drugs, tramadol and topical anaesthetics drugs. Treatment with α1-adrenoceptor antagonists cannot be recommended until the results of large well-designed RCTs are published in major international peer-reviewed medical journals. As our understanding of the neurochemical control of ejaculation improves, new therapeutic targets and candidate molecules will be identified which may increase our pharmacotherapeutic armamentarium.

Drug interactions between antiretrovirals and drugs used to treat benign prostatic hyperplasia/lower urinary tract symptoms

INTRODUCTION

Significant advances in antiretroviral (ARV) therapy have transformed HIV into a chronic manageable disease. Co-morbidities associated with aging, such as benign prostatic hyperplasia (BPH), are becoming increasingly prevalent in the HIV-infected population. The pharmacological treatment of BPH involves medications mainly metabolized by CYP 450 enzymes, while many ARVs have inducing or inhibiting effects on the CYP 450 system. Consequently, there is potential for significant pharmacokinetic (PK) interactions between these two classes of medications.

AREAS COVERED

This article reviews the pharmacology and metabolism of selected BPH drug therapies and ARVs, in addition to highlighting potential interactions between these two drug categories. The authors also present PK evidence of interactions from available clinical trials, product monographs and international conference abstracts. Potentially significant drug interactions are summarized and strategies for management are discussed.

EXPERT OPINION

Drugs most likely to interact with BPH medications include protease inhibitors, the non-nucleoside reverse transcriptase inhibitors efavirenz, nevirapine, etravirine, and the cobicistat-boosted integrase inhibitor elvitegravir. Clinically significant PK interactions with BPH medications and dolutegravir, raltegravir, rilpivirine, or the investigational agent doravirine do not appear to exist. Clinicians working with HIV-infected individuals need to recognize the potential for interactions involving BPH and ARV treatments to ensure effective and safe drug therapy use.

Current and Emerging Treatments for Premature Ejaculation

INTRODUCTION

Over the past 20-30 years, the premature ejaculation (PE) treatment paradigm, previously limited to behavioral psychotherapy, has expanded to include drug treatment. Pharmacotherapy for PE predominantly targets the multiple neurotransmitters and receptors involved in the control of ejaculation, which include serotonin, dopamine, oxytocin, norepinephrine, gamma amino-butyric acid (GABA) and nitric oxide (NO).

AIM

The objective of this article is to review current and emerging PE interventions.

METHODS

Contemporary data on the treatment of PE were reviewed and critiqued using the principles of evidence-based medicine.

MAIN OUTCOME MEASURE

Integrated pharmacotherapy and cognitive behavioral therapy (CBT) may achieve superior treatment outcomes in some patients. Phosphodiesterase type 5 inhibitors alone or in combination with selective serotonin reuptake inhibitors (SSRIs) should be limited to men with acquired PE secondary to comorbid erectile dysfunction (ED). New on-demand rapid-acting SSRIs, oxytocin receptor antagonists, or single agents that target multiple receptors may form the foundation of more effective future on-demand medication.

RESULTS

Multiple well-controlled evidence-based studies have demonstrated the efficacy and safety of SSRIs in delaying ejaculation, confirming their role as first-line agents for the medical treatment of lifelong and acquired PE. Daily dosing of SSRIs is likely to be associated with superior fold increases in intravaginal ejaculation latency time compared with on-demand SSRIs. On-demand SSRIs are less effective but may fulfill the treatment goals of many patients.

CONCLUSIONS

Current evidence suggests that psychosexual CBT has a limited role in the contemporary management of PE and confirms the efficacy and safety of dapoxetine, off-label SSRI drugs, and topical anesthetics drugs. Treatment with tramadol, α1-adrenoceptor antagonists cannot be recommended until the results of large, well-designed randomized controlled trials are published in major international peer-reviewed medical journals. As our understanding of the neurochemical control of ejaculation improves, new therapeutic targets and candidate molecules will be identified, which may increase our pharmacotherepeutic armamentarium. McMahon CG. Current and emerging treatments for premature ejaculation. Sex Med Rev 2015;3:183-202.

Safety and efficacy of 8-mg once-daily vs 4-mg twice-daily silodosin in patients with lower urinary tract symptoms suggestive of benign prostatic hyperplasia (SILVER Study): a 12-week, double-blind, randomized, parallel, multicenter study

OBJECTIVE

To show the noninferiority of silodosin 8-mg once-daily (QD) to 4-mg twice-daily (BID) in efficacy and safety in patients with lower urinary tract symptoms or benign prostatic hyperplasia in the Korean population.

METHODS

A prospective, multicenter, double-blind, randomized, comparative study was conducted. A total of 532 male patients aged ≥50 years with lower urinary tract symptoms or benign prostatic hyperplasia were included. All patients received silodosin QD or BID for 12 weeks. The primary end point was the change from baseline in total International Prostate Symptom Score (IPSS) at 12 weeks. Adverse drug reactions, vital signs, and laboratory tests were recorded.

RESULTS

A total of 424 patients were randomized to the silodosin QD or BID groups. These groups were not significantly different in baseline characteristics. The mean total IPSS change in QD group was not inferior to that in BID group (-6.70 and -6.94, respectively; 95% confidence interval, -0.88 to 1.36). The QD and BID groups did not significantly differ in the following: percentages of patients with ≥25% (63.41% and 67.82%, respectively; P = .349) or ≥4-point improvement in total IPSS (65.85% and 69.31%, respectively; P = .457), maximum urinary flow rate improvement ≥30% (47.32% and 40.59%, respectively; P = .172), changes in IPSS voiding subscore (-4.42 ± 4.93 and -4.65 ± 4.77; P = .641), IPSS storage subscore (-2.05 ± 3.07 and -2.52 ± 2.97; P = .117), quality of life (-1.19 ± 1.49 and -1.40 ± 1.42; P = .136), maximum urinary flow rate (3.55 ± 5.93 and 3.74 ± 6.79 mL/s; P = .768), International Continence Society male questionnaire score, Patient Goal Achievement Score, or Treatment Satisfaction Question. The 2 groups had similar frequencies of adverse drug reactions.

CONCLUSION

QD administration of silodosin was not inferior to BID in efficacy. The 2 groups had similar adverse drug reaction profiles.

Global QSAR modeling of logP values of phenethylamines acting as adrenergic alpha-1 receptor agonists

Global QSAR models predict biological response of molecular structures which are generic in particular class. A global QSAR dataset admits structural features derived from larger chemical space, intricate to model but more applicable in medicinal chemistry. The present work is global in either sense of structural diversity in QSAR dataset or large number of descriptor input. Forty phenethylamine structure derivatives were selected from a large pool (904) of similar phenethylamines available in Pubchem database. LogP values of selected candidates were collected from physical properties database (PHYSPROP) determined in identical set of conditions. Attempts to model logP value have produced significant QSAR models. MLR aided linear one-variable and two-variable QSAR models with their respective R(2) (0.866, 0.937), R(2)A (0.862, 0.932), F-stat (181.936, 199.812) and Standard Error (0.365, 0.255) are statistically fit and found predictive after internal validation and external validation. The descriptors chosen after improvisation and optimization reveal mechanistic part of work in terms of Verhaar model of Fish base-line toxicity from MLOGP, i.e. (BLTF96) and 3D-MoRSE -signal 15 /unweighted molecular descriptor calculated by summing atom weights viewed by a different angular scattering function (Mor15u) are crucial in regulation of logP values of phenethylamines.

Silodosin is effective for treatment of LUTS in men with BPH: a systematic review

The aim of this study was to systematically review the evidence on the efficacy and safety of silodosin treatments on lower urinary tract symptoms (LUTS) in men with benign prostatic hyperplasia (BPH) from randomized controlled trials. We searched PubMed (1966-December 2011), Embase (1974-December 2011) and the Cochrane Library Database (2011, Issue 12). The assessed outcome measures were the change from baseline for the International Prostate Symptom Score (IPSS), quality of life (QoL) score, peak urine maximum flow rate (Q(max)), QoL related to urinary symptoms and adverse effects. Two authors independently assessed the study quality and extracted data. All data were analysed using RevMan 5.1. The meta-analysis included four randomized controlled trials with a total of 2504 patients. The study durations were each 12 weeks. At the follow-up end points, the pooled results showed that the change from baseline for the silodosin group was significantly higher than the placebo group for the IPSS, QoL score and Q(max)(mean difference (MD)=-2.78, P<0.00001; MD=-0.42, P=0.004; MD=1.17, P<0.00001,respectively) and patients felt more satisfied with QoL related to urinary symptoms in the silodosin group than the placebo group. Ejaculation disorder was the most commonly reported adverse effect. The pooled results also showed that the silodosin group was superior to the 0.2 mg tamsulosin group with respect to the IPSS and QoL score (IPSS: MD=-1.14, P=0.02; QoL score: MD=-0.26, P=0.02) and inferior to the 0.2 mg tamsulosin group with respect to Q(max) (MD=-0.85, P=0.01). In contrast, there was no significant difference in the incidence of ejaculation disorder and dizziness between the silodosin and 0.2 mg tamsulosin groups. The current meta-analysis suggested that silodosin is an effective therapy for LUTS in men with BPH and is not inferior to 0.2 mg tamsulosin.

Comparison of the effects of four α1-adrenoceptor antagonists on ejaculatory function in rats

OBJECTIVE

To compare the effects of four α(1)-adrenoceptor (AR) subtype-selective antagonists on ejaculatory function in rats to investigate whether the differences in their modes of action-based on their selectivities for the α(1A)-AR subtype-would be related to the prevalence of ejaculation disorder (EjD).

METHODS

The effects of α(1)-AR antagonists on noradrenaline-induced contractions were studied in rat isolated seminal vesicles, vas deferens, bladder trigone, and prostate. Male rats were given α(1)-AR antagonists orally and, 1 hour after the drug administration they were cohoused in pairs for 1 hour with untreated female rats certified to be in estrus. The number of copulatory plugs (NP) present after mating was measured as a marker of EjD. Drug effects on ejaculatory function (ie, on NP) were compared with those on the prostatic urethra (ie, phenylephrine-induced increase in intraurethral pressure [IUP]).

RESULTS

All α(1)-AR antagonists concentration-dependently inhibited noradrenaline-induced contraction in all 4 tissues, and there were no differences in the rank order of potencies (tamsulosin > silodosin > alfuzosin > naftopidil) among the tissues. All α(1)-AR antagonists dose-dependently decreased NP and inhibited the phenylephrine-induced increase in IUP. There was little difference in the dose ratio ID(50) value (dose required to produce 50% inhibition) for NP/ID(50) value for IUP response among the four drugs. Drug potencies associated NP and IUP correlated closely with affinities for the human α(1A)-AR.

CONCLUSION

α(1)-AR antagonists cause EjD as a class effect that depends on affinity for α(1A)-AR. Differences in α(1A)-AR selectivity would be unlikely to be related to the incidence of EjD.

Effect of extended-term estrogen on voiding in a postpartum ovariectomized rat model

INTRODUCTION

We tested the hypothesis that extended-term (5-week) estrogen therapy would negatively impact voiding function in a postpartum, ovariectomized rat model.

METHODS

Immediately after delivery, 30 primiparous Sprague-Dawley rats underwent intravaginal balloon dilation, followed by ovariectomy 1 week later. Cystometry at postpartum week 2 determined normal or abnormal voiding patterns. After randomization, one-half the normal and abnormal voiding rats received 5 weeks of estrogen therapy, while the remainder received placebo. Estrogen effect was determined by repeat cystometry and immunohistochemical analysis of the urethra and vagina.

RESULTS

Abnormal voiding increased from 60.0% to 73.3% in the estrogen- treated group and declined from 60% to 33% for the placebo group. Rats were then divided into 4 groups for comparison: normal voiding versus placebo (group 1), abnormal voiding versus placebo (group 2), normal voiding versus estrogen (group 3) and abnormal voiding versus estrogen (group 4). Bladder capacity, leak point pressure and maximum voiding pressure were most depressed in group 4. Estrogen treatment was associated with a significant downregulation of alpha(1A) and alpha(1D)-adrenoceptors in the urethral submucosa but an upregulation of nNOS in the urethral smooth muscle.

CONCLUSION

Extended-term estrogen therapy in a rat model of simulated birth trauma and ovariectomy resulted in a higher rate of incontinence. Immunohistochemical examination demonstrated significant downregulation of urethral alpha(1A)- and alpha(1D)-adrenoceptors and upregulation of neuronal nitric oxide synthase (nNOS) in the urethra of estrogen-treated groups. These studies question the use of hormone replacement therapy in the treatment of postmenopausal incontinence.

α(1)-Adrenoceptors in the urinary tract

α(1)-Adrenoceptors have been identified and characterized extensively by functional, radioligand-binding, and molecular biological techniques. Molecular clones have been isolated for three α(1)-subtypes (α(1a), α(1b), and α(1d)), and these subtypes are also functionally characterized. α(1)-Adrenoceptors are present in the prostate, urethra, bladder (urothelium, smooth muscle, and afferent nerves), ureter, vas deferens, peripheral ganglia, nerve terminals, vascular tissues, and central nervous system (CNS), and they could all potentially influence overall urinary function and contribute to both the therapeutic and adverse effects of α(1)-adrenoceptor antagonists in patients with benign prostatic hyperplasia (BPH) and lower urinary tract symptoms (LUTS). This review aimed to discuss the relevant physiological and pharmacological roles and molecular biology of α(1)-adrenoceptor subtypes in the prostate, urethra, bladder, ureter, and CNS.

Conversion to Silodosin in Men on Conventional α1 -Blockers for Symptomatic Benign Prostatic Hyperplasia

OBJECTIVES

α1 -blockers have commonly been used as first-line medical therapy for symptomatic benign prostatic hyperplasia (BPH). Recently, a highly selective α1A -adrenoceptor antagonist, silodosin, was developed in Japan. We examined the efficacy and safety of conversion from conventional α1 -blockers to silodosin in men with BPH.

METHODS

Conversion to silodosin was proposed to consecutive patients on conventional α1 -blockers for symptomatic BPH for at least 6 months. The effects of conversion were examined by the International Prostate Symptom Score, quality of life index, overactive bladder symptom score, peak flow rate, residual urine volume, and adverse events at 12 weeks. The efficacy of silodosin was also evaluated by patients' impression.

RESULTS

Eighty-one men underwent conversion, for the most part because of dissatisfaction with the efficacy of their current treatment in improving nocturia or weak stream. The International Prostate Symptom Score total score significantly improved from 12.7 ± 5.9 at baseline to 10.6 ± 5.4 at 4 weeks (P < 0.001) and 10.9 ± 5.8 at 12 weeks (P < 0.01). The progress was mostly due to improvement in voiding symptoms, although reduction of storage symptoms was also significant. The quality of life index also significantly decreased with conversion to silodosin. Efficacy as judged by patients' impression was 76% (37/49) at 12 weeks of treatment. None of the overactive bladder symptom score, peak flow rate, and residual urine volume exhibited significant change. No serious adverse events were observed during the study period.

CONCLUSION

Conversion to silodosin may be beneficial in men who are dissatisfied with conventional α1 -blockers for BPH, and be particularly useful in improving voiding symptoms.

Effect of silodosin on specific urinary symptoms associated with benign prostatic hyperplasia: analysis of international prostate symptom scores in 2 phase III clinical studies

PURPOSE

Pooled results from 2 randomized, placebo-controlled, US phase III studies (NCT00224107, NCT00224120) showed that silodosin, a uroselective α-blocker, significantly improved International Prostate Symptom Scores (IPSS) in men with symptomatic benign prostatic hyperplasia (BPH). This analysis evaluated the effect of silodosin on each symptom assessed by IPSS questionnaire.

MATERIALS AND METHODS

Study participants (N = 923) were men aged ≥50 years with IPSS ≥13 and Qmax 4-15 mL/s. They received silodosin 8 mg or placebo once daily for 12 weeks. Patient responses to 7 IPSS questions were collected at weeks 0 (baseline), 0.5, 1, 2, 4, and 12 and scored on a 6-point scale. Efficacy of silodosin versus placebo was assessed by analysis of covariance.

RESULTS

For each symptom, the 2 treatment groups had similar mean baseline scores. Decrease in score from baseline (mean ± standard deviation) to last observation was significantly greater with silodosin than with placebo for all symptoms (P < 0.005); symptom improvement with silodosin (versus placebo) was greatest for weak stream (silodosin, -1.1 ± 1.4 versus placebo, -0.5 ± 1.2; P < 0.0001) and smallest for nocturia (silodosin, -0.6 ± 1.1 versus placebo, -0.4 ± 1.2; P = 0.0037). Compared with placebo, silodosin significantly improved nocturia within 1 week (silodosin, -0.5 ± 1.07 versus placebo, -0.3 ± 1.05; P = 0.009) and all other symptoms within 3 to 4 days (P < 0.01).

CONCLUSIONS

Silodosin significantly improved all BPH-associated symptoms assessed by IPSS questionnaire within the first week of treatment. All improvements were maintained over the 12-week study period.

Pathophysiology of benign prostatic hyperplasia: insights from medical therapy for the disease

The medical treatment of benign prostatic hyperplasia (BPH) has its roots in the early 1970s. During this era, the first clinical trials investigating alpha-blockade and androgen deprivation therapy were reported for men with clinical BPH. The observation that clinical BPH was improved following administration of both alpha-blockers and androgen deprivation therapy supported the evolving paradigm that clinical BPH resulted from dynamic and static pathways. During the past several decades, the evolution of alpha-blockers for the treatment of BPH has been impacted by innovations targeted to simplify the administration and improve tolerability while maintaining their effectiveness.

A meta-analysis of the vascular-related safety profile and efficacy of alpha-adrenergic blockers for symptoms related to benign prostatic hyperplasia

OBJECTIVES

To evaluate the safety profile and efficacy of alpha1-adrenergic receptor blockers (A1Bs) currently prescribed for benign prostatic hyperplasia (BPH).

DATA SOURCES

A systematic literature search of MEDLINE, the Cochrane Database and the Food and Drug Administration Web site through December 2006 identified double-blinded, prospective, placebo-controlled trials, evaluating agents commercially available by prescription for the symptomatic treatment of BPH.

REVIEW METHODS

Data were reviewed by two investigators with the use of a standardised data abstraction form. Studies were evaluated for methodological quality using the Jadad scale. Studies with a score of < 3 were considered of weaker methodology.

RESULTS

Of 2389 potential citations, 25 were usable for evaluation of safety data, 26 for efficacy. A1B use was associated with a statistically significant increase in the odds of developing a vascular-related event [odds ratio (OR) 2.54; 95% confidence interval (CI): 2.00-3.24; p < 0.0001]. The odds of developing a vascular-related adverse event were: alfuzosin, OR 1.66, 95% CI: 1.17-2.36; terazosin, OR 3.71, 95% CI: 2.48-5.53; doxazosin, OR 3.32, 95% CI: 2.10-5.23 and tamsulosin, OR 1.42, 95% CI: 0.99-2.05. A1Bs increased Q(max) by 1.32 ml/min (95% CI: 1.07-1.57) compared with placebo. Difference from placebo in American Urological Association symptom index/International Prostate Symptom Score was -1.92 points (95% CI: -2.71 to -1.14).

CONCLUSIONS

Alfuzosin, terazosin and doxazosin showed a statistically significant increased risk of developing vascular-related events compared with placebo. Tamsulosin showed a numerical increase that was not statistically significant. All agents significantly improved Q(max) and symptom signs compared with placebo.

Effects of estrogen, raloxifene and levormeloxifene on alpha1A-adrenergic receptor expression

PURPOSE

We investigated the effect of estrogen, raloxifene and levormeloxifene on alpha1A-adrenergic receptor expression.

MATERIALS AND METHODS

Postpartum rats underwent intravaginal balloon injury and ovariectomy, and were then treated with estrogen or placebo for 8 weeks. The urethras were examined for alpha1A-adrenergic receptor expression by Western blot analysis and immunohistochemistry. Urethral smooth muscle cells were isolated from untreated female rats and examined for the expression of estrogen receptors alpha and beta by immunofluorescence microscopy. Urethral smooth muscle cells were treated with estrogen, raloxifene or levormeloxifene for 24 hours and examined for alpha1A-adrenergic receptor expression by real-time polymerase chain reaction. The effects of these drugs on alpha1A-adrenergic receptor expression were further examined by promoter assays.

RESULTS

Estrogen treatment resulted in decreased alpha1A-adrenergic receptor expression in the urethras. Urethral smooth muscle cells expressed estrogen receptors alpha and beta, the former predominantly in the cytoplasm and the latter in the nucleus. Estrogen significantly down-regulated alpha1A-adrenergic receptor mRNA expression, while raloxifene and levormeloxifene had no significant effect. Estrogen also significantly down-regulated alpha1A-adrenergic receptor promoter in the presence of estrogen receptor alpha or beta. Raloxifene and levormeloxifene up-regulated alpha1A-adrenergic receptor promoter in the presence of estrogen receptor alpha but not beta.

CONCLUSIONS

Estrogen down-regulated alpha1A-adrenergic receptor expression in the urethral smooth muscle of female rats, while raloxifene and levormeloxifene had no significant effect. These findings represent a possible molecular mechanism through which estrogen, raloxifene and levormeloxifene differentially affect urinary continence.

Benign prostatic hyperplasia and lower urinary tract symptoms in African Americans and Latinos: treatment in the context of common comorbidities

Benign prostatic hyperplasia (BPH), with accompanying lower urinary tract symptoms (LUTS), is a common age-related condition associated with a variety of cardiovascular, metabolic, and sexual comorbidities. While there is debate, in the United States race and ethnicity, particularly among Latinos and African American men, may confer an elevated risk for BPH and LUTS. Hypertension and deficits in sexual health are more common among African American men, while both Latino and African American men experience more metabolic-related disorders, including diabetes mellitus, insulin resistance, and end-stage renal disease. Although socioeconomic factors may play a significant role in these disparities, pathological and genetic variations between patients of different races and ethnicities are additional factors in the development of BPH. The proliferation of available treatments for BPH demands greater discernment in treatment selection, and comorbidities represent a central criterion upon which choice of appropriate BPH therapy should be based. This article reviews common comorbidities in minority populations, describes challenges to BPH management, and discusses medical, surgical, and phytotherapeutic treatment options.

Comorbid LUTS and erectile dysfunction: optimizing their management

BACKGROUND AND SCOPE

Lower urinary tract symptoms (LUTS) related to benign prostatic hyperplasia (BPH), and sexual dysfunction such as erectile dysfunction (ED), are highly prevalent in men over the age of 50. LUTS and ED have a negative impact on sexual function and when comorbid, result in reduced quality of life. The goal of this article is to discuss the relationship between ED and LUTS, describe the diagnostic workup of these disorders, explore the current treatment options, and examine how treatments may affect this population. Medline (1980-2006), Cochrane reviews, and the American Urological Association 2006 General Meeting abstracts were searched for relevant clinical trials and reviews with the terms: benign prostatic hyperplasia, lower urinary tract symptoms, erectile dysfunction, sexual dysfunction, alpha-adrenergic receptor antagonists, alpha-blockers, 5alpha-reductase inhibitors, phosphodiesterase type-5 inhibitors, transurethral resection of the prostate, transurethral microwave thermotherapy, transurethral needle ablation, adverse events, alfuzosin, doxazosin, tamsulosin, terazosin, dutasteride, finasteride, sildenafil, tadalafil, vardenafil. However, because of the volume of literature, this article is not a systematic review.

FINDINGS

Although age is an independent risk factor for both LUTS and ED, studies report that LUTS is also an independent risk factor for ED. Treatments for LUTS include pharmacologic, minimally invasive, and surgical therapies. Among pharmacologic options, alpha1-adrenergic receptor (alpha1-AR) antagonists provide effective treatment with a low risk of sexual side-effects; some of these drugs have been reported to improve sexual function. The treatment of LUTS may improve ED. Phosphodiesterase type 5 inhibitors (PDE-5s) are considered first-line therapy for ED. Comorbid LUTS and ED are treated with an alpha1-AR antagonist and a PDE-5; however, this combination must be used with caution because of vasodilatory adverse events associated with both classes of drugs.

CONCLUSIONS

Optimal management includes screening to identify patients with comorbid LUTS and ED, and the use of treatments that minimize both vasodilatory and sexual side-effects.

The role of alpha-blockers in the management of lower urinary tract symptoms in prostate cancer patients treated with radiation therapy

OBJECTIVE

Radiation therapy (RT) is commonly used for the treatment of prostate cancer, either via brachytherapy or external beam, and is often accompanied by dose-related obstructive and irritative lower urinary tract symptoms (LUTS). This review will analyze the current state of knowledge of LUTS secondary to RT for prostate cancer and review treatment options for this complication.

METHODS

A review of the literature.

RESULTS

Radiation-induced effects in the lower urinary tract that result in LUTS include injury to peripheral neurons, interstitial fibrosis of the bladder, and loss of muscle fibers in the muscularis propria. LUTS are associated with a diminished quality of life and impaired sexual function. Numerous nonrandomized studies and one randomized study support the proposition that the occurrence of LUTS secondary to RT is effectively mitigated by alpha1-adrenoreceptor blockade.

CONCLUSIONS

Basic and clinical science studies as well as clinical guidelines relevant for LUTS secondary to RT suggest that the routine use of alpha1-adrenoreceptor antagonists should be considered in patients treated with RT, either prophylactically or at the earliest sign of LUTS.

Alpha1A/L-adrenoceptors mediate contraction of the circular smooth muscle of the pig urethra

Sympathetically mediated urethral tone is essential for the maintenance of continence and involves the activation of postjunctional alpha(1)-adrenoceptors. This study characterizes the alpha(1)-adrenoceptor subtypes responsible for mediating contraction of the urethral circular smooth muscle of the pig. The potency order of a number of agonists and the affinities of several receptor selective antagonists were determined on pig-isolated circular smooth muscle strips in the presence of cocaine (1 microm) and corticosterone (10 microm) to inhibit amine uptake and propranolol (1 microm) to antagonize beta-adrenoceptors. The potency order for agonists was N-[5-(4,5-dihydro-1H-imidazol-2yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulphonamide (A61603) > noradrenaline = phenylephrine = M6434 > methoxamine with pEC(50) values of 7.3, 5.8, 5.7, 5.6 and 5.0 respectively. 4 The alpha(1D)-adrenoceptor-selective antagonist 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4,5]decane-7,9-dione (BMY7378) caused rightward shifts of the concentration-response curves to noradrenaline, yielding a low affinity estimate (6.6) for the urethral receptor. The alpha(1A)-adrenoceptor-selective antagonists, RS100329 and 5-methylurapidil, gave relatively high affinity estimates (9.6 and 8.8 respectively) for this receptor. All three antagonists produced Schild plots with slopes close to unity but did reduce maximum responses at higher concentrations. Prazosin antagonized responses of the urethra to noradrenaline, yielding a mean affinity estimate of 9.0. Although the Schild plot for prazosin again had a slope of unity, this drug also reduced maximum responses to noradrenaline at all concentrations examined (10-100 nm). N-[2-(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-alpha,alpha-dimethyl-1H-indole-3-ethanamide (RS17053), which discriminates between responses mediated via alpha(1A) (high affinity) and alpha(1L)-adrenoceptors (low affinity) at concentrations up to 3 microm, failed to antagonize responses of the urethra. 5 These results suggest that contraction of urethral circular smooth muscle in the pig is mediated via a single population of adrenoceptors with the pharmacological characteristics of the alpha(1A/L)-adrenoceptor, most probably the alpha(1L)-adrenoceptor.

Silodosin, a new alpha1A-adrenoceptor-selective antagonist for treating benign prostatic hyperplasia: results of a phase III randomized, placebo-controlled, double-blind study in Japanese men

OBJECTIVE

To verify the efficacy and safety of the new alpha1A-adrenoceptor-selective antagonist silodosin compared with tamsulosin and placebo in patients with lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH).

PATIENTS AND METHODS

This randomized, double-blind, placebo-controlled study was conducted at 88 centres in Japan. Men aged > or = 50 years with an International Prostate Symptom Score (IPSS) of > or = 8, a quality-of-life (QoL) score of > or = 3, a maximum urinary flow rate (Qmax) of < 15 mL/s, a prostate volume of > or = 20 mL and a postvoid residual urine volume of < 100 mL were eligible for enrolment. Patients were randomized to receive silodosin 4 mg twice daily, tamsulosin 0.2 mg once daily, or placebo, for 12 weeks. The primary endpoint was the change in IPSS from baseline. Safety was assessed by adverse events, physical examination, vital signs and laboratory tests.

RESULTS

In all, 457 patients were randomized (silodosin 176, tamsulosin 192 and placebo 89). The change in the total IPSS from baseline in the silodosin, tamsulosin and placebo groups was -8.3, -6.8 and -5.3, respectively. There was a significant decrease in the IPSS vs placebo in the silodosin group from 1 week. In the early-stage comparison, silodosin showed a significant decrease in IPSS vs tamsulosin at 2 weeks. The change in QoL from baseline was -1.7, -1.4 and -1.1 in the silodosin, tamsulosin and placebo groups, respectively; silodosin showed a significant improvement in the QoL score vs placebo. In the subgroup of patients with severe symptoms (IPSS > or = 20) silodosin also gave a significantly better improvement than placebo (-12.4 vs -8.7). The incidence rates of adverse events and drug-related adverse events were, respectively, 88.6%, 82.3% and 71.6% and 69.7%, 47.4% and 36.4%, respectively. The most common adverse event in the silodosin group was abnormal ejaculation, which occurred more often in the silodosin than in the tamsulosin group (22.3% vs 1.6%). However, only five men (2.9%) discontinued treatment for abnormal ejaculation.

CONCLUSION

Silodosin was generally effective in the absence of obtrusive side-effects. This study suggests that silodosin is clinically useful for treating LUTS associated with BPH.

Alpha-adrenoceptors are a common denominator in the pathophysiology of erectile function and BPH/LUTS - implications for clinical practice

A literature search of PubMed documented publications and abstracts from proceedings of scientific meetings was made to review the available data on benign prostatic hyperplasia/lower urinary tract symptoms (BPH/LUTS) and erectile dysfunction (ED) with a special focus on the role of alpha-adrenoceptors as critical mediators of pathophysiology. The reader is introduced to clinical results on the therapeutic potential of alpha-blockers alone and in combination with phosphodiesterase type 5 (PDE-5) inhibitors in the treatment of ED associated with LUTS/BPH. Epidemiological studies clearly show that an association exists between ED and LUTS/BPH. The severity of LUTS is correlated with the risk for ED. A significant number of LUTS/BPH patients are nonresponsive to the common ED treatment with PDE-5 inhibitors. As smooth muscle contractility is regulated by adrenoceptors in the corpus cavernosum, prostate and detrusor, the alpha-adrenoceptor system may be considered a common pathophysiological mediator in the development of ED and LUTS/BPH. Blockade of alpha-adrenoceptors for the treatment of BPH/LUTS may have the potential of improving sexual function. Conversely, PDE-5 inhibitors may exhibit positive effects in LUTS patients. Pilot studies on combination regimens of alpha-adrenoceptor antagonists and PDE-5 inhibitors have yielded encouraging results in LUTS patients with persistent ED. On the basis of pharmacological and clinical evidence, it is established that the alpha-adrenoceptor system plays an important role in the pathophysiology of ED and LUTS secondary to BPH. Larger trials on the combination of alpha-adrenoceptor antagonists with PDE-5 inhibitors are necessary to develop an integrated treatment approach for BPH/LUTS patients with comorbid ED.

Uroselectivity in male dogs of silodosin (KMD-3213), a novel drug for the obstructive component of benign prostatic hyperplasia

AIMS

Our main aim was to compare the prostatic selectivity of silodosin with that of other alpha(1)-adrenoceptor (AR) antagonists.

METHODS

We examined uroselectivities in two sets of experiments namely, in vitro and in vivo functional studies using male dogs. In the in vitro study, after evaluating the inhibitory effects of silodosin on noradrenaline (NA)-induced contractions in the isolated prostate and isolated carotid artery using the Magnus method, we calculated prostatic selectivity. In the in vivo study, we examined the effects of drugs on the hypogastric nerve stimulation (HNS)-induced increase in intraurethral pressure (IUP) and on blood pressure. The uroselectivity of silodosin was compared with those of tamsulosin and naftopidil.

RESULTS

In vitro, all drugs antagonized NA-induced contraction in both prostate and carotid artery. The prostatic selectivity of silodosin (79.4) was much higher than those of tamsulosin (1.78), naftopidil (0.55), BMY 7378 (0.115), and prazosin (0.01). In vivo, intravenously (i.v.) administered silodosin dose-dependently inhibited the HNS-induced increase in IUP with much less hypotensive effect than either tamsulosin or naftopidil, the uroselectivity (ED(15)/ID(50)) of silodosin (237) being significantly higher than those of tamsulosin (1.21) and naftopidil (2.65).

CONCLUSIONS

Our results clearly demonstrate that silodosin is a potent and highly selective alpha(1A)-AR antagonist. A selective alpha(1A)-AR antagonist such as silodosin may have good potential as a less-hypotensive drug for the treatment of urinary dysfunction in benign prostatic hyperplasia patients.

α1-Adrenoceptor Subtype Selectivity and Organ Specificity of Silodosin (KMD-3213)

The selectivity of silodosin (KMD-3213), an antagonist of alpha(1)-adrenoceptor (AR), to the subtypes (alpha(1A)-, alpha(1B)- and alpha(1D)-ARs) was examined by a receptor-binding study and a functional pharmacological study, and we compared its subtype-selectivity with those of other alpha(1)-AR antagonists. In the receptor-binding study, a replacement experiment using [(3)H]-prazosin was conducted using the membrane fraction of mouse-derived LM (tk-) cells in which each of three human alpha(1)-AR subtypes was expressed. In the functional pharmacological study, the following isolated tissues were used as representative organs with high distribution densities of alpha(1)-AR subtypes (alpha(1A)-AR: rabbit prostate, urethra and bladder trigone; alpha(1B)-AR: rat spleen; alpha(1D)-AR: rat thoracic aorta). Using the Magnus method, we studied the inhibitory effect of silodosin on noradrenaline-induced contraction, and compared it with those of tamsulosin hydrochloride, naftopidil and prazosin hydrochloride. Silodosin showed higher selectivity for the alpha(1A)-AR subtype than tamsulosin hydrochloride, naftopidil or prazosin hydrochloride (affinity was highest for tamsulosin hydrochloride, followed by silodosin, prazosin hydrochloride and naftopidil in that order). Silodosin strongly antagonized noradrenaline-induced contractions in rabbit lower urinary tract tissues (including prostate, urethra and bladder trigone, with pA(2) or pKb values of 9.60, 8.71 and 9.35, respectively). On the other hand, the pA(2) values for antagonism of noradrenaline-induced contractions in rat isolated spleen and rat isolated thoracic aorta were 7.15 and 7.88, respectively. Selectivity for lower urinary tract was higher for silodosin than for the other alpha(1)-AR antagonists. Our data suggest that silodosin has a high selectivity for the alpha(1A)-AR subtype and for the lower urinary tract.

Effect of Silodosin on Intraurethral Pressure Increase Induced by Hypogastric Nerve Stimulation in Dogs with Benign Prostatic Hyperplasia

We compared the urethral and cardiovascular effects of silodosin (selective alpha(1A)-adrenoceptor antagonist), a novel medication for benign prostatic hyperplasia (BPH), with those of tamsulosin (selective alpha(1A)/alpha(1D)-adrenoceptor antagonist) and naftopidil (selective alpha(1D)-adrenoceptor antagonist). We evaluated the effects of these three drugs on the increase in intraurethral pressure (IUP) induced by electrical stimulation of the hypogastric nerve in anesthetized dogs with spontaneous BPH. All three drugs dose-dependently reduced both the increase in IUP and the mean blood pressure (MBP). The rank order of potencies was tamsulosin>silodosin>naftopidil for the reductions in both IUP and MBP. However, the uroselectivity (ED(15) value for hypotensive effect/ID(50) value for reduction in IUP) of silodosin (uroselectivity, 19.8) was about 21 and 4 times higher than that of tamsulosin (0.939) and naftopidil (4.94), respectively. These data suggest that silodosin might be one of the most useful medications for dysuria in BPH patients.

Lower urinary tract symptoms/benign prostatic hyperplasia: fast control of the patient's quality of life

Fast control of bothersome symptoms and improvement in the patient's quality of life (QOL) are important treatment goals in lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia. Although voiding symptoms are most common, storage symptoms are most bothersome, interfere the most with daily life activities, and have a major effect on QOL. alpha(1)-Adrenoceptor antagonists, such as tamsulosin, improve the most bothersome storage symptoms to roughly the same extent as transurethral resection of the prostate (TURP), whereas the effect on voiding symptoms is slightly less. This may be because tamsulosin relieves storage symptoms as quickly and to the same extent as voiding symptoms, whereas TURP improves storage symptoms to a lesser extent and/or more slowly than voiding symptoms. In addition, alpha(1)-adrenoceptor antagonists have a more rapid onset of action and seem to be slightly more effective in improving LUTS, its bothersomeness, and QOL than 5alpha-reductase inhibitors, such as finasteride. It also seems that alpha(1)-adrenoceptor antagonists have a more rapid onset of action than the plant extract Serenoa repens. Because the alpha(1A)/alpha(1D)-adrenoceptor antagonist tamsulosin has a low risk for symptomatic orthostatic hypotension, it can be initiated at its full therapeutic dose immediately at the start of therapy. This enables faster relief of bothersome LUTS than non-subtype-selective alpha(1)-adrenoceptor antagonists that require dose titration to their full therapeutic dose. In the long term, adding finasteride to an alpha(1)-adrenoceptor antagonist may be beneficial in high-risk patients, but adding S repens does not seem to provide any additional benefit (up to 1 year). In conclusion, monotherapy with an alpha(1A)/alpha(1D)-adrenoceptor antagonist, such as tamsulosin, provides very effective and rapid relief of bothersome LUTS and so enables a rapid improvement of the patient's QOL.

Lower urinary tract symptoms/benign prostatic hyperplasia: minimizing morbidity caused by treatment

The beneficial effects of treatment for lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH), or LUTS/BPH, have to be balanced against the morbidity associated with treatment. Invasive surgery, such as transurethral resection of the prostate, has been associated with irreversible complications (eg, impotence and retrograde ejaculation). Alpha(1)-adrenoceptor antagonists provide effective and fast relief of LUTS/BPH. In contrast to finasteride, they are not associated with sexual dysfunction (eg, decreased libido or impotence). Alpha(1)-adrenoceptor antagonists induce adverse events associated with interference with blood pressure regulation. The alpha(1A)/alpha(1D)-adrenoceptor antagonist tamsulosin has the lowest potential to interfere with blood pressure regulation and induce related adverse events. In addition, tamsulosin seems to be as well tolerated as phytotherapy, except for a higher incidence of abnormal ejaculation. Abnormal ejaculation occurs in 4% to 11% of patients receiving a alpha(1)-adrenoceptor antagonist, which is, however, well tolerated; <1% of patients discontinue because of this adverse event. In placebo-controlled trials, abnormal ejaculation has been predominantly reported for tamsulosin, but in most direct comparative studies, the incidence was comparable to that of other alpha(1)-adrenoceptor antagonists. Men with LUTS/BPH have an increased risk of impaired sexual function. However, alpha(1)-adrenoceptor antagonists, such as tamsulosin, may slightly improve sexual dysfunction together with LUTS problems. Combination therapy of an alpha(1)-adrenoceptor antagonist and finasteride has a similar adverse-event profile as each monotherapy, except for an increased risk of abnormal ejaculation. The discontinuation rate because of adverse events does not seem to be higher than with monotherapy. Medical therapies, and particularly alpha(1)-adrenoceptor antagonists such as tamsulosin, can be considered a first-line treatment option for LUTS/BPH because they provide effective relief of bothersome LUTS with excellent tolerability.

Synthesis, pharmacology and pharmacokinetics of 3-(4-aryl-piperazin-1-ylalkyl)-uracils as uroselective alpha1A-antagonists

Predominance in the urethra and prostate of the alpha(1A)-adrenoceptor subtype, which is believed to be the receptor mediating noradrenaline induced smooth muscle contraction in these tissues, led to the preparation of alpha(1A)-selective antagonists to be tested as uroselective compounds for the treatment of benign prostatic hyperplasia. Thus, a number of selective alpha(1A)-adrenoceptor antagonists were synthesized and assayed in vitro for potency and selectivity. Dog pharmacokinetic parameters of 12 (RO700004) and its metabolite 40 (RO1104253) were established. The relative selectivity of intravenously administered 12, 40 and standard prazosin to inhibit hypogastric nerve stimulation-induced increases in intraurethral prostatic pressure versus phenylephrine-induced increases in diastolic blood pressure in anesthetized dogs was 76, 71 and 0.6, respectively.

Effects of KMD-3213, a uroselective alpha 1A-adrenoceptor antagonist, on the tilt-induced blood pressure response in normotensive rats

KMD-3213 ((-)-1-(3-hydroxypropyl)-5-((2R)-2-[[2-([2-[(2,2,2-trifluoroethyl)oxy]phenyl]oxy)ethyl]amino]propyl)-2,3-dihydro-1H-indole-7-carboxamide), an alpha(1A)-adrenoceptor antagonist with potency similar to that of tamsulosin, is under development for the treatment of bladder outlet obstruction in patients with benign prostatic hypertrophy. In the present study, we investigated the effects of KMD-3213 on the tilt-induced blood pressure response in anesthetized normotensive rats. Male normotensive Sprague-Dawley rats were placed in the supine position on a board under cocktail anesthetization (alpha-chloralose, urethane and sodium pentobarbital). The arterial blood pressure was measured from the carotid artery. The animals were given consistent 45 degrees head-up tilt from the horizontal position, following the transient decrease in the blood pressure, and then recovery of the blood pressure to the normal level. Significant orthostatic hypotension was seen with intravenous administration of both prazosin and tamsulosin at doses over 3 micro g/kg, and these drugs completely blocked the tilt-induced blood pressure responses at 30 micro g/kg. On the other hand, these responses were still retained when KMD-3213 was administered intravenously at a dose up to 75 micro g/kg of KMD-3213. Moreover, KMD-3213 showed the highest uroselectivity of the test drugs. These results indicate that KMD-3213 is not likely to induce orthostatic hypotension and would be a useful compound for the treatment of urinary outlet obstruction in patients with benign prostatic hyperplasia.

Selective and sustained occupancy of prostatic alpha1-adrenoceptors by oral administration of KMD-3213 and its plasma concentration in rats

This study examined the ex-vivo occupancy by KMD-3213 of alpha1-adrenoceptors in the prostate and other tissues of rats in terms of tissue selectivity and duration of occupancy in relation to plasma concentration. Oral administration of KMD-3213 (0.2-20.2 micromol kg(-1), 0.5 h) dose-dependently decreased [3H]prazosin binding sites (Bmax) in the prostate (42-74%) and submaxillary gland (54-88%) compared with the control value. In contrast, there was only a slight change in the Bmax values in the spleen and cerebral cortex of KMD-3213-treated rats. The alpha1-adrenoceptor occupancy in the prostate and submaxillary gland was increased, with plasma free concentration of KMD-3213 at 0.5 h after oral administration of KMD-3213 (0.6-20.2 micromol kg(-1)). The receptor occupancy in these tissues was much greater than that in the spleen, heart or cerebral cortex. After oral administration of KMD-3213 (6.1 micromol kg(-1)), the alpha1-adrenoceptor occupancy in the prostate and submaxillary gland occurred rapidly, in parallel with the rise in the plasma concentration of the drug, and it lasted for at least 24 h, despite a remarkable decrease in the plasma concentration. It is concluded that KMD-3213 may produce fairly selective and sustained occupancy of alpha1-adrenoceptors in the prostate, a target organ for treatment of bladder outlet obstruction in patients with benign prostatic hyperplasia.

Alfuzosin: a review of the therapeutic use of the prolonged-release formulation given once daily in the management of benign prostatic hyperplasia

Alfuzosin, a quinazoline derivative, is a selective and competitive alpha(1)-adrenoceptor antagonist. It distributes preferentially in the prostate, compared with plasma, and decreases the sympathetically controlled tone of prostatic smooth muscle. As a result lower urinary tract symptoms suggestive of benign prostatic hyperplasia (BPH) are improved. The once-daily formulation of alfuzosin contains inactive barrier layers which have been added to the planar surfaces of compressed tablets. Drug release is sustained over 20 hours with a near constant dissolution rate between 2 and 12 hours. Mean values for area under the plasma concentration-time curve over 24 hours (AUC(24)) were similar after administration of prolonged-release alfuzosin 10mg once daily and immediate-release alfuzosin 2.5mg three times daily. Likewise, similar AUC(24) values were reported when prolonged-release alfuzosin 10mg once daily and sustained-release alfuzosin 5mg twice daily were compared. These data suggest that these alfuzosin regimens provide similar average systemic exposure. Data from short- (3 months) and long-term (up to 12 months) clinical trials show that the prolonged-release formulation of alfuzosin controls the symptoms associated with BPH as effectively as immediate-release alfuzosin 2.5mg three times daily and clinical improvement is maintained for up to 1 year. Improvements in International Prostate Symptom Score, maximum urinary flow rate and quality-of-life index were improved to a similar extent in patients treated with immediate- or prolonged-release alfuzosin and improvements were statistically significant compared with placebo. Prolonged-release alfuzosin 10mg is well tolerated and the overall incidence of adverse events is similar to that seen with placebo. The once-daily formulation of alfuzosin 10mg caused fewer vasodilatory adverse events than immediate-release alfuzosin 2.5mg three times daily and caused only slight decreases in systolic and diastolic blood pressure which were not clinically significant and did not differ significantly from those with placebo. No dosage titration is required. The incidence of ejaculatory disorders was <1%.

CONCLUSION

Prolonged-release alfuzosin 10mg once daily controls symptoms associated with BPH throughout a 24-hour dosage interval as effectively as immediate-release alfuzosin 2.5mg three times daily but with fewer vasodilatory adverse events. A nonblind extension study showed that clinical benefits were maintained for up to 1 year and the once-daily 10mg formulation continued to be well tolerated, particularly in terms of cardiovascular effects and sexual function. Thus, for the medical management of men with BPH, prolonged-release alfuzosin 10mg is an effective, well tolerated and convenient treatment option.

The use of alpha-adrenoceptor antagonists in lower urinary tract disease

alpha-adrenoceptor antagonists have traditionally been used in the treatment of hypertension but in recent years they have become increasingly common in the treatment of benign prostatic enlargement (BPE), where they reduce the 'dynamic' component of bladder outlet obstruction and appear to have additional actions to reduce irritative symptoms of the disease. Prazosin (Hypovase), Alza), doxazosin (Cardura), Pfizer), indoramin (Doralese), Wyeth-Ayerst Pharmaceuticals Inc.) and terazosin (Hytrin), Abbott Laboratories) are currently available in the UK for BPE but these agents have cardiovascular actions in a significant number of patients, inducing effects which must be considered adverse unless the patient also requires treatment for mild-to-moderate hypertension. The uroselective alpha-adrenoceptor antagonists tamsulosin (Flomax), Yamanouchi Pharmaceutical Co. Ltd.) and alfuzosin (Xatral), Sanofi-Synthelabo) have recently been introduced. These agents exert their selectivity via different mechanisms; selective tissue distribution for alfuzosin and alpha-adrenoceptor subtype selectivity for tamsulosin. The incidence of cardiovascular side effects for both drugs is similar to placebo. Several lines of evidence suggest that the alpha-adrenoceptor antagonists may relieve lower urinary tract (LUT) symptoms by other mechanisms additional to those which account for the reduction in bladder outlet obstruction. If correct, these agents may be of use in the treatment of other bladder conditions.