Pharmacology of tamsulosin: saturation-binding isotherms and competition analysis using cloned alpha 1-adrenergic receptor subtypes

α1-Adrenergic Receptors: Insights into Potential Therapeutic Opportunities for COVID-19, Heart Failure, and Alzheimer's Disease

α1-Adrenergic receptors (ARs) are members of the G-Protein Coupled Receptor superfamily and with other related receptors (β and α2), they are involved in regulating the sympathetic nervous system through binding and activation by norepinephrine and epinephrine. Traditionally, α1-AR antagonists were first used as anti-hypertensives, as α1-AR activation increases vasoconstriction, but they are not a first-line use at present. The current usage of α1-AR antagonists increases urinary flow in benign prostatic hyperplasia. α1-AR agonists are used in septic shock, but the increased blood pressure response limits use for other conditions. However, with the advent of genetic-based animal models of the subtypes, drug design of highly selective ligands, scientists have discovered potentially newer uses for both agonists and antagonists of the α1-AR. In this review, we highlight newer treatment potential for α1A-AR agonists (heart failure, ischemia, and Alzheimer's disease) and non-selective α1-AR antagonists (COVID-19/SARS, Parkinson's disease, and posttraumatic stress disorder). While the studies reviewed here are still preclinical in cell lines and rodent disease models or have undergone initial clinical trials, potential therapeutics discussed here should not be used for non-approved conditions.

Polymorphisms in common antihypertensive targets: Pharmacogenomic implications for the treatment of cardiovascular disease

The idea of personalized medicine came to fruition with sequencing the human genome; however, aside from a few cases, the genetic revolution has yet to materialize. Cardiovascular diseases are the leading cause of death globally, and hypertension is a common prelude to nearly all cardiovascular diseases. Thus, hypertension is an ideal candidate disease to apply tenants of personalized medicine to lessen cardiovascular disease. Herein is a survey that visually depicts the polymorphisms in the top eight antihypertensive targets. Although there are numerous genome-wide association studies regarding cardiovascular disease, few studies look at the effects of receptor polymorphisms on drug treatment. With 17,000+ polymorphisms in the combined target proteins examined, it is expected that some of the clinical variability in the treatment of hypertension is due to polymorphisms in the drug targets. Recent advances in techniques and technology, such as high throughput examination of single mutations, structure prediction, computational power for modeling, and CRISPR models of point mutations, allow for a relatively rapid and comprehensive examination of the effects of known and future polymorphisms on drug affinity and effects. As hypertension is easy to measure and has a plethora of clinically viable ligands, hypertension makes an excellent disease to study pharmacogenomics in the lab and the clinic. If the promises of personalized medicine are to materialize, a concerted effort to examine the effects polymorphisms have on drugs is required. A clinician with the knowledge of a patient's genotype can then prescribe drugs that are optimal for treating that specific patient.

Efficacy of Adjuvant Tamsulosin for Improving the Stone-Free Rate after Extracorporeal Shock Wave Lithotripsy in Renal Stones: A Randomized Controlled Trial

INTRODUCTION

Extracorporeal shock wave lithotripsy (ESWL) is an effective treatment for urolithiasis. Tamsulosin is capable of causing dilation and facilitating the migration of stones. The aim of this study is to evaluate the efficacy of adjuvant treatment with tamsulosin for improving the stone-free rate after a single session of ESWL in the treatment of kidney stones.

METHODS

This is a randomized, nonplacebo-controlled study with a sample of 60 adults with a single radiopaque kidney stone of 5-20 mm in diameter. After the ESWL session, the patients were divided into two groups. The control group received standard treatment for analgesia consisting of oral diclofenac (75 mg/12 h) as needed. The tamsulosin group received standard treatment for analgesia plus oral tamsulosin (0.4 mg/day) for eight weeks. In both groups, stone-free status was determined using a CT scan eight weeks after ESWL. The protocol of this study was registered with ClinicalTrials.gov, identifier: NCT04819828.

RESULTS

Only 57 patients completed the study (28 tamsulosin and 29 control). Overall, the average stone diameter was 11.42 ± 4.52 mm. The stone-free rate was 50.88% (29 of 57) overall, 53.57% (15 of 28) for the tamsulosin group, and 48.27% (14 of 29) for the control group (p = 0.680). The estimated relative risk in favor of the tamsulosin group to achieve a stone-free status was 1.11 (95% CI 0.67-1.9). The estimated number needed to treat to achieve a single patient with renal stone-free status after eight weeks of ESWL adjuvant treatment with tamsulosin was 19.

CONCLUSION

Our findings suggest that tamsulosin as adjuvant treatment after a single ESWL session is well tolerated and safe, but it does not increase the stone-free rate in patients with a single radiopaque renal stone of 5-20 mm in diameter. Our results may support the use of tamsulosin with ESWL in the case of patients with a single radiopaque renal stone of 11-20 mm in diameter based on an apparent higher stone-free rate and a low rate of complications.

Comparison of the Efficacy of Male Sexual Activity Versus Alpha-Blockers in the Expulsion of Distal Ureteric Stones: A Systematic Review and Meta-Analysis

Globally, the prevalence of urolithiasis is increasing, with limited effective treatment options. Though debate exists within the literature, the use of medical expulsive therapy (MET) for distal ureteric stones in the form of alpha-blockers is commonplace. Alpha-blockers work via the inhibition of norepinephrine, resulting in a small degree of distal ureteric relaxation. Nitric oxide (NO), the main neurotransmitter involved in penile erection, causes smooth muscle relaxation of the distal ureter. It is hypothesised that these alternative pathways may achieve the same desire clinical effect. To our knowledge, this is the first meta-analysis comparing the efficacy of male sexual activity, in the form of intercourse or masturbation, to alpha-blockers in the expulsion of ureteric stones. We conducted a comprehensive search of electronic databases (PubMed, MEDLINE, EMBASE, SCOPUS, CENTRAL and Google Scholar), identifying studies comparing male sexual activity versus alpha-blockers, in male patients with distal ureteric stones. The Cochrane risk-of-bias tool was used to assess the included studies. For data analysis, a random effects model was used in the event of significant heterogeneity (>75%), with fixed-effects modelling in the event of low-moderate heterogeneity. A search of electronic databases found three randomised control trials (RCTs), enrolling a total of 262 patients. There was no statistically significant difference observed when patients engaged in sexual activity rather than alpha-blocker, when looking at stone expulsion rate at two weeks (P=0.36), expulsion rate at four weeks (P=0.57), or the mean stone expulsion time (P=0.21). Furthermore, there was no significant difference observed when looking at analgesic requirements (P=0.43), or the requirement for additional procedures (P=0.57). Our meta-analysis demonstrated that male sexual activity as an alternative therapy for distal ureteric stones had comparable outcomes to the use of alpha-blocker, proving a viable alternative therapy in those patients wishing to avoid pharmacological management.

Revisiting the Pharmacodynamic Uroselectivity of α 1-Adrenergic Receptor Antagonists

α₁-Adrenoceptor (AR) antagonists are widely used for the relief of urinary retention secondary to benign prostatic hyperplasia (BPH). While the five Food and Drug Administration-approved α ₁-AR antagonists (terazosin, doxazosin, alfuzosin, tamsulosin, and silodosin) share similar efficacy, they differ in tolerability, with reports of ejaculatory dysfunction. The aim of the present work was to revisit their α ₁-AR subtype selectivity as well as of LDT5 (1-(2-methoxyphenyl)-4-[2-(3,4-dimethoxyphenyl) ethyl]piperazine monohydrochloride), a compound previously described as a multitarget antagonist of α _1A-/α _1D-AR and 5-HT_1A receptors, and to estimate their affinity for D₂, D₃, and 5-HT_1A receptors, which are putatively involved in ejaculatory dysfunction. Competition binding assays were performed with native (D₂, 5-HT_1A) or transfected (human α _1A-, α _1B-, α _1Dt-AR, and D₃) receptors for determination of the drug's affinities. Tamsulosin and silodosin have the highest affinities for α _1A-AR, but only silodosin is clearly a selective α _1A-AR antagonist, with K _i ratios of 25.3 and 50.2 for the α _1D- and α _1B-AR, respectively. Tamsulosin, silodosin, and LDT5 (but not terazosin, doxazosin, and alfuzosin) have high affinity for the 5-HT_1A receptor (K _i around 5-10 nM), behaving as antagonists. We conclude that the uroselectivity of tamsulosin is not explained by its too-low selectivity for the α _1A- versus α _1B-AR, and that its affinity for D₂ and D₃ receptors is probably too low for explaining the ejaculatory dysfunction reported for this drug. Present data also support the design of "better-than-LDT5" new multitarget lead compounds with pharmacokinetic selectivity based on poor brain penetration and that could prevent hyperplastic cell proliferation and BPH progression. SIGNIFICANCE STATEMENT: The present work revisits the uroselectivity of the five Food and Drug Administration-approved α₁ adrenoceptor antagonists for the treatment of benign prostatic hyperplasia (BPH). Contrary to what has been claimed by some, our results indicate that the uroselectivity of tamsulosin is probably not fully explained by its too-weak selectivity for the α_1A versus α_1B adrenoceptors. We also show that tamsulosin affinity for D₃ and 5-HT_1A receptors is probably too low for explaining the ejaculatory dysfunction reported for this drug. Based on our lead compound LDT5, present data support the search for a multitarget antagonist of α_1A-α_1D and 5-HT_1A receptors with poor brain penetration as an alternative for BPH treatment.

Adjunction of tamsulosin or mirabegron before semi-rigid ureterolithotripsy improves outcomes: prospective, randomized single-blind study

OBJECTIVE

To evaluate efficiency and safety of adjunct tamsulosin and mirabegron therapy before semi-rigid ureteroscopy for ureteral stones.

MATERIALS AND METHODS

In this prospective, randomized, single-blind and multicentric study, participants were randomized into three groups. Group 1 was the control, participants in Group 2 used tamsulosin, and those in Group 3 used mirabegron. Operations were performed 7 days after drug administration. In all clinics, a 6/7.5-Fr ureteroscope with a laser power source for lithotripsy was used.

RESULTS

After excluding participants whose stones spontaneously passed, who discontinued medication due to adverse events and who were lost to follow-up, 186 participants were included in the final analysis. Mean age, gender, laterality, stone distribution and mean stone surface area were similar between groups. The number of participants requiring balloon dilatation was higher in the control group (23.8%) than in the tamsulosin (8.2%) and mirabegron (6.5%) groups (p = 0.006). Successful access rate was lower in the control group (81%) than in the tamsulosin (96.7%) and mirabegron (95.2%) groups (p = 0.003). Stone-free rate was lower in the control group (77.8%) than in the tamsulosin (90.2%) and mirabegron (95.2%) groups (p = 0.01). Complication rates were similar among groups.

CONCLUSIONS

Tamsulosin or mirabegron use for 1 week before semi-rigid ureteroscope increases stone access and the stone-free rate. Tamsulosin or mirabegron can be used with safety and efficacy before ureteroscopy for ureteral stones.

Efficacy of silodosin on the outcome of semi-rigid ureteroscopy for the management of large distal ureteric stones: blinded randomised trial

Objective

To evaluate the efficacy of silodosin therapy, as a new α-adrenergic receptor (α-AR) blocker, on the success rate of semi-rigid ureteroscopy (URS) for the management of large distal ureteric stones.

Patients and methods

This prospective study recruited 127 adult patients with single distal ureteric stone of ≥1 cm. The patients were randomly allocated to two groups: the first group included 62 patients who received silodosin (8 mg) for 10 days before URS (Silodosin group), whilst the second group included 65 patients who received placebo, in the form of multivitamins, for 10 days before URS (Placebo group). All patients underwent URS and a pneumatic lithoclast was used for stone fragmentation.

Results

The mean (SD) operative time was shorter in the Silodosin group compared with the Placebo group, at 41.61 (4.67) vs 46.85 (4.6) min, respectively. Furthermore, advancing the ureteroscope to access the stone failed in a statistically significant number of patients in the Placebo group compared with the Silodosin group (13 vs two, respectively). The complication rate was significantly higher in the Placebo group compared with the Silodosin group (20% vs 6.4%, P = 0.036). Additionally, the need for postoperative analgesia was significantly lower in the Silodosin group compared with the Placebo group (8.1% vs 26.2%, P = 0.009).

Conclusion

Silodosin therapy prior to URS management of large distal ureteric stones seems to be associated with better advancing of the ureteroscope to access the stone, shorter procedure time, higher stone-free rate, lower incidence of complications, and lesser need for postoperative analgesia.

Medical expulsive therapy for ureteric stones: Analysing the evidence from systematic reviews and meta-analysis of powered double-blinded randomised controlled trials

Objective

To conduct a systematic review and meta-analysis investigating the efficacy and safety of medical expulsive therapy (MET) in low risk of bias (RoB) randomised controlled trials (RCTs).

Methods

A Cochrane style systematic review was conducted on published literature from 1990 to 2016, to include low RoB and a power calculation. A pooled meta-analysis was conducted.

Results

The MET group included 1387 vs 1381 patients in the control group. The analysis reveals α-blockers increased stone expulsion rates (78% vs 74%) (P < 0.001), whilst calcium channel blockers (CCBs) had no effect compared to controls (79% vs 75%) (P = 0.38). In the subgroup analysis, α-blockers had a shorter time to stone expulsion vs the control group (P < 0.001). There were no significant differences in expulsion rates between the treatment groups and control group for stones <5 mm in size (P = 0.48), proximal or mid-ureteric stones (P = 0.63 and P = 0.22, respectively). However, α-blockers increased stone expulsion in stones >5 mm (P = 0.02), as well as distal ureteric stones (P < 0.001). The α-blocker group developed more side-effects (6.6% of patients; P < 0.001). The numbers needed to treat for α-blockers was one in 14, for stones >5 mm one in eight, and for distal stones one in 10.

Conclusion

The primary findings show a small overall benefit for α-blockers as MET for ureteric stones but no benefit with CCBs. α-blockers show a greater benefit for large (>5 mm) ureteric stones and those located in the distal ureter, but no benefit for smaller or more proximal stones. α-blockers are associated with a greater risk of side-effects compared to placebo or CCBs.

Differential effects of the enantiomers of tamsulosin and tolterodine on P-glycoprotein and cytochrome P450 3A4

The pregnane X receptor (PXR) is a transcription factor regulating P-glycoprotein (P-gp; ABCB1)-mediated transport and cytochrome P450 3A4 (CYP3A4)-mediated metabolism of xenobiotics thereby affecting the pharmacokinetics of many drugs and potentially modulating clinical efficacy. Thus, pharmacokinetic drug-drug interactions can arise from PXR activation. Here, we examined whether the selective α1-adrenoreceptor blocker tamsulosin or the antagonist of muscarinic receptors tolterodine affect PXR-mediated regulation of CYP3A4 and of P-gp at the messenger RNA (mRNA) and protein level in an enantiomer-specific way. In addition, the effect of tamsulosin and tolterodine on P-gp activity was evaluated. We used quantitative real-time PCR, gene reporter assay, western blotting, rhodamine efflux assay, and calcein assay for determination of expression, activity, and inhibition of P-glycoprotein. The studied compounds significantly and concentration-dependently increased PXR activity in the ABCB1-driven luciferase-based reporter gene assay. We observed much stronger induction of ABCB1 mRNA by S-tamsulosin as compared to the R or racemic form. R or racemic form of tolterodine and R-tamsulosin concentration-dependently increased P-gp protein expression; the latter also enhanced P-gp efflux function in a rhodamine-based efflux assay. R-tamsulosin and all forms of tolderodine slightly inhibited P-gp. The effect on CYP3A4 expression followed the same pattern but was much weaker. Taken together, tamsulosin and tolterodine are demonstrated to interfere with P-gp and CYP3A4 regulation in an enantiomer-specific way.

Use of drug therapy in the management of symptomatic ureteric stones in hospitalised adults: a multicentre, placebo-controlled, randomised controlled trial and cost-effectiveness analysis of a calcium channel blocker (nifedipine) and an alpha-blocker (tamsulosin) (the SUSPEND trial)

BACKGROUND

Ureteric colic, the term used to describe the pain felt when a stone passes down the ureter from the kidney to the bladder, is a frequent reason for people to seek emergency health care. Treatment with the muscle-relaxant drugs tamsulosin hydrochloride (Petyme, TEVA UK Ltd) and nifedipine (Coracten(®), UCB Pharma Ltd) as medical expulsive therapy (MET) is increasingly being used to improve the likelihood of spontaneous stone passage and lessen the need for interventional procedures. However, there remains considerable uncertainty around the effectiveness of these drugs for routine use.

OBJECTIVES

To determine whether or not treatment with either tamsulosin 400 µg or nifedipine 30 mg for up to 4 weeks increases the rate of spontaneous stone passage for people with ureteric colic compared with placebo, and whether or not it is cost-effective for the UK NHS.

DESIGN

A pragmatic, randomised controlled trial comparing two active drugs, tamsulosin and nifedipine, against placebo. Participants, clinicians and trial staff were blinded to treatment allocation. A cost-utility analysis was performed using data gathered during trial participation.

SETTING

Urology departments in 24 UK NHS hospitals.

PARTICIPANTS

Adults aged between 18 and 65 years admitted as an emergency with a single ureteric stone measuring ≤ 10 mm, localised by computerised tomography, who were able to take trial medications and complete trial procedures.

INTERVENTIONS

Eligible participants were randomised 1 : 1 : 1 to take tamsulosin 400 µg, nifedipine 30 mg or placebo once daily for up to 4 weeks to make the following comparisons: tamsulosin or nifedipine (MET) versus placebo and tamsulosin versus nifedipine.

MAIN OUTCOME MEASURES

The primary effectiveness outcome was the proportion of participants who spontaneously passed their stone. This was defined as the lack of need for active intervention for ureteric stones at up to 4 weeks after randomisation. This was determined from 4- and 12-week case-report forms completed by research staff, and from the 4-week participant self-reported questionnaire. The primary economic outcome was the incremental cost per quality-adjusted life-year (QALY) gained over 12 weeks. We estimated costs from NHS sources and calculated QALYs from participant completion of the European Quality of Life-5 Dimensions health status questionnaire 3-level response (EQ-5D-3L™) at baseline, 4 weeks and 12 weeks.

RESULTS

Primary outcome analysis included 97% of the 1167 participants randomised (378/391 tamsulosin, 379/387 nifedipine and 379/399 placebo participants). The proportion of participants who spontaneously passed their stone did not differ between MET and placebo [odds ratio (OR) 1.04, 95% confidence interval (CI) 0.77 to 1.43; absolute difference 0.8%, 95% CI -4.1% to 5.7%] or between tamsulosin and nifedipine [OR 1.06, 95% CI 0.74 to 1.53; absolute difference 1%, 95% CI -4.6% to 6.6%]. There was no evidence of a difference in QALYs gained or in cost between the trial groups, which means that the use of MET would be very unlikely to be considered cost-effective. These findings were unchanged by extensive sensitivity analyses around predictors of stone passage, including sex, stone size and stone location.

CONCLUSIONS

Tamsulosin and nifedipine did not increase the likelihood of stone passage over 4 weeks for people with ureteric colic, and use of these drugs is very unlikely to be cost-effective for the NHS. Further work is required to investigate the phenomenon of large, high-quality trials showing smaller effect size than meta-analysis of several small, lower-quality studies.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN69423238. European Clinical Trials Database (EudraCT) number 2010-019469-26.

FUNDING

This project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 19, No. 63. See the NIHR Journals Library website for further project information.

Sildenafil citrate as a medical expulsive therapy for distal ureteric stones: A randomised double-blind placebo-controlled study

Objective

To study the effect of sildenafil citrate on spontaneous passage of distal ureteric stones (DUS).

Patients and methods

This was a randomised double-blinded placebo-controlled study of 100 patients with DUS. Inclusion criteria were: male, age 18–65 years, normal renal function, and a single radiopaque unilateral DUS of 5–10 mm. Patients were randomly allocated into two equal groups, one that received placebo and the other that received 50 mg sildenafil citrate once daily. Both investigators and patients were masked to the type of treatment. Patients self-administered the medication until spontaneous passage of the DUS. In patients where there was uncontrolled pain, fever, an increase in serum creatinine of >1.8 mg/dL, progressive hydronephrosis or no further progress after 4 weeks, a decision was taken for further treatment.

Results

In all, 47 and 49 patients were available for analysis in both the placebo and sildenafil citrate groups; respectively. Both groups were comparable for age and stone characteristics. Spontaneous expulsion occurred in 19 of 47 patients (40.4%) in the placebo group and in 33 of 49 (67.3%) in the sildenafil citrate group (P = 0.014). The mean time to stone expulsion was significantly shorter in the sildenafil citrate group (P < 0.001). A multivariable Cox proportional hazards model showed that receiving sildenafil citrate was the only independent factor that had a significant impact on stone passage with a hazard ratio of 2.7 (95% confidence interval 1.5–4.8; P < 0.001).

Conclusion

Sildenafil citrate enhances spontaneous passage of 5–10 mm DUS.

Risks associated with drug treatments for kidney stones

INTRODUCTION

Renal stones are one of the most painful medical conditions patients experience. For many they are also a recurrent problem. Fortunately, there are a number of drug therapies available to treat symptoms as well as prevent future stone formation.

AREAS COVERED

Herein, we review the most common drugs used in the treatment of renal stones, explaining the mechanism of action and potential side effects. Search of the Medline databases and relevant textbooks was conducted to obtain the relevant information. Further details were sourced from drug prescribing manuals. Recent studies of drug effectiveness are included as appropriate.

EXPERT OPINION

Recent controversies include medical expulsive therapy trials and complex role of urinary citrate in stone disease. Future directions in research will involve new medical therapies for stone prevention, for example new drugs for hyperoxaluria.

Analysis of factors affecting spontaneous expulsion of ureteral stones that may predict unfavorable outcomes during watchful waiting periods: What is the influence of diabetes mellitus on the ureter?

Purpose

The aim of our study was to evaluate the association of several factors with spontaneous stone expulsion, including ureteral stone characteristics (size, location, hydronephrosis, perinephric stranding), types of medications prescribed (α-blocker, low-dose steroid), and other possible demographic and health-history factors (gender, age, serum creatinine, underlying diabetes mellitus [DM], and hypertension).

Materials and Methods

A total of 366 patients with ureteral stones were enrolled. All patients underwent watchful waiting without any invasive procedures. Initial diagnoses of ureteral stones were confirmed by computed tomography scans, which were taken at approximately 1-month intervals to check for stone expulsion. Univariate and multivariate analyses were conducted to identify significant factors that contributed to stone expulsion.

Results

Among 366 patients, 335 patients (91.5%) experienced spontaneous stone passage during a mean follow-up period of 2.95±2.62 weeks. The patients were divided into two groups depending on the success of spontaneous stone passage. Univariate analyses revealed that stone location (p=0.003), stone size (p=0.021), and underlying DM (p<0.001) were significant predictors of stone passage. Multivariate analyses confirmed that stone size (p=0.010), stone location (p=0.008), and underlying DM (p=0.003) were independent predictive factors affecting stone passage.

Conclusions

Stone size, location, and underlying DM were confirmed to be significant predictive factors for spontaneous passage of ureteral stones. Urologists should consider active procedures, such as shock wave lithotripsy or ureteroscopy, rather than conservative management in patients presenting with proximally located stones, large ureteral stones, or underlying DM.

Anterior segment morphologic changes related to α-1 adrenergic receptor antagonists use

PURPOSE

To investigate possible changes in anterior segment parameters with the Pentacam in patients taking tamsulosin or doxazosin for benign prostatic hyperplasia.

METHODS

This prospective, cross-sectional study was conducted at Necip Fazil City Hospital, Kahramanmaras, Turkey. Patients included in the study were grouped as follows: 29 patients treated with tamsulosin (group 1), 27 patients treated with doxazosin (group 2), and 40 untreated controls (group 3). Right eyes of each patient were included in the study. All patients underwent examination with the Pentacam under standard dim light conditions and with undilated pupils. Anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA) width, central corneal thickness (CCT), corneal volume (CV), and pupil diameter (PD) were recorded.

RESULTS

Mean duration of treatments was 2.7 ± 1.2 (1-5) and 2.4 ± 0.9 (1-5) years in groups 1 and 2 (p = 0.276). The ACD, ACV, ACA width, and PD were statistically significantly decreased in groups 1 and 2 when compared to group 3 (p&lt;0.05). There were no statistically significant differences among the groups in mean values of CCT and CV.

CONCLUSIONS

In this study, decreased ACD, ACV, ACA width, and PD values were detected in tamsulosin and doxazosin groups when compared to controls. These findings should be considered during anterior segment examinations and surgeries.

Wound dehiscence as a cataract surgery-associated postoperative complication in patients previously treated with alpha-1 blocker tamsulosin--a population-based study in Taiwan

PURPOSE

To compare the cataract surgery-related complications between patients with and without tamsulosin treatment.

DESIGN

A nationwide retrospective case-control study.

METHODS

Patients who had undergone cataract surgery were identified using the International Classification of Disease, Ninth Revision, Clinical Modification from a nationally representative dataset of 1 million people selected from the Taiwan National Health Insurance Research Database in 2000. Patients preoperatively treated with α1-blockers before cataract surgery were the treated group, and age-, sex-, and year of surgery-matched patients not preoperatively treated with α1-blockers were the control group. Patients treated with tamsulosin underwent subgroup analysis. A conditional logistic regression model was used to estimate surgery-related complications and interesting variables. The main outcome measures are cataract surgery-related complications.

RESULTS

A total of 4474 treated patients and 4474 controls were analyzed. The percentage of cataract surgery-related complications was 8.61% in the treated group and 8% in the control group (not significantly different). However, wound dehiscence was 3.81 times higher (95% confidence interval: 1.24-11.67, P = .0194) in the tamsulosin-treated group.

CONCLUSIONS

Patients treated with tamsulosin have a higher risk of wound dehiscence after cataract surgery. Carefully taking a history of tamsulosin use before cataract surgery is advised so that some strategies can be used to prevent complications and additional costs.

Use of drug therapy in the management of symptomatic ureteric stones in hospitalized adults (SUSPEND), a multicentre, placebo-controlled, randomized trial of a calcium-channel blocker (nifedipine) and an α-blocker (tamsulosin): study protocol for a randomized controlled trial

Background

Urinary stone disease is common, with an estimated prevalence among the general population of 2% to 3%. Ureteric stones can cause severe pain and have a significant impact on quality of life, accounting for over 15,000 hospital admissions in England annually. Uncomplicated cases of smaller stones in the lower ureter are traditionally treated expectantly. Those who fail standard care or develop complications undergo active treatment, such as extracorporeal shock wave lithotripsy or ureteroscopy with stone retrieval. Such interventions are expensive, require urological expertise and carry a risk of complications.

Growing understanding of ureteric function and pathophysiology has led to the hypothesis that drugs causing relaxation of ureteric smooth muscle, such as the selective α-blocker tamsulosin and the calcium-channel blocker nifedipine, can enhance the spontaneous passage of ureteric stones. The use of drugs in augmenting stone passage, reducing the morbidity and costs associated with ureteric stone disease, is promising. However, the majority of clinical trials conducted to date have been small, poor to moderate quality and lacking in comprehensive economic evaluation.

This trial aims to determine the clinical and cost-effectiveness of tamsulosin and nifedipine in the management of symptomatic urinary stones.

Methods/design

The SUSPEND (Spontaneous Urinary Stone Passage ENabled by Drugs) trial is a multicentre, double-blind, randomized controlled trial evaluating two medical expulsive therapy strategies (nifedipine or tamsulosin) versus placebo.

Patients aged 18 to 65 with a ureteric stone confirmed by non-contrast computed tomography of the kidney, ureter and bladder will be randomized to receive nifedipine, tamsulosin or placebo (400 participants per arm) for a maximum of 28 days. The primary clinical outcome is spontaneous passage of ureteric stones at 4 weeks (defined as no further intervention required to facilitate stone passage). The primary economic outcome is a reduction in the incremental cost per quality-adjusted life years, determined at 12 weeks. The analysis will be based on all participants as randomized (intention to treat). The trial has 90% power with a type I error rate of 5% to detect a 10% increase in primary outcome between the tamsulosin and nifedipine treatment groups.

Trial registration

ISRCTN69423238; EudraCT number: 2010-019469-26

α1-Adrenergic receptor antagonists and gynecomastia. A case series from the Italian spontaneous reporting system and VigiBase(™)

PURPOSE

The aim of this study was to analyze the cases of gynecomastia associated with α1A-adrenergic receptor antagonists (α1-ARAs) in the Italian spontaneous reporting system database (Rete Nazionale di Farmacovigilanza or RNF) and in the World Health Organization ICSRs database (VigiBase(™)), focusing on tamsulosin use.

METHODS

We analyzed the spontaneous reports of gynecomastia related to the use of α1-ARAs and collected from the RNF and from VigiBase(™) up to December 2012. Cases of gynecomastia have been defined as reports associated with gynecomastia according with Medical Dictionary for Regulatory Activities (MedDRA). Reporting odds ratio (ROR) and Information Component (IC) were calculated as measures of disproportionality in RNF and VigiBase(™), respectively.

RESULTS

Up to December 2012, about 186,000 reports were recorded in the RNF. Among these, 902 reports of adverse drug reaction (ADR) have been associated with the use of at least one α1-ARAs. Of these, in 15 cases, gynecomastia was a listed ADR: in 10, the suspected drug was tamsulosin (in eight, it was the sole suspect); in two, doxazosin and alfuzosin, respectively; and in one, terazosin. ROR for tamsulosin was 5.3 (95% CI 1.8, 15.7). In VigiBase(™), 84 reports of gynecomastia indicated tamsulosin as suspected drug. Tamsulosin-associated gynecomastia showed the highest IC value within this class of drugs (IC 95% 2.43).

CONCLUSION

In this study, we highlight a possible association between gynecomastia and tamsulosin use. To our knowledge, this association has not been described before and could represent a potential signal.

Effect of tamsulosin on stone expulsion in proximal ureteral calculi: an open-label randomized controlled trial

AIM

Medical expulsive therapy (MET) using alpha-blockers is effective for distal ureteral calculi (UC). We aimed to evaluate the efficacy of tamsulosin for proximal UC expulsion.

MATERIALS AND METHODS

An open-label randomized controlled trial was conducted with 108 patients who agreed to conservative management for single, radiopaque, proximal UC ≤ 6 mm and were randomized into group A (n = 54, conservative managements only) or B (n = 54, 0.2 mg tamsulosin once a day). The primary end-point was stone passage rates (SPR) in the intention-to-treat population in 4 treatment weeks. The secondary end-points were estimated in per-protocol population and were time to stone passage, post-trial Euro-quality-of-life (EuroQOL) score, oral analgesic requirements, and willingness to undergo conservative treatment again.

RESULTS

The two groups were well balanced in terms of baseline patient and stone characteristics. Seventy nine patients (73.2%; 35 of group A and 44 of group B) completed the study protocol. The overall SPR was 60.2% (65/108). Group B had a higher SPR (74.1%; 40/54) than group A (46.3%; 25/54; p = 0.003) and a significantly shorter time to stone passage (mean days, A: 19.6 vs. B: 14.3, p = 0.005). The groups did not differ in post-trial EuroQOL score or oral analgesic requirements, whereas 74.3% (26/35) of group A and 90.9% (40/44) of group B were willing to undergo conservative treatment again (p = 0.048). Univariate logistic regression analysis showed that stone size (OR = 1.447, p = 0.045) and tamsulosin treatment (OR = 3.314, p = 0.004) significantly predicted stone expulsion. On multivariate analysis, only tamsulosin was statistically significant (OR=3.198, p = 0.021).

CONCLUSIONS

Tamsulosin was associated with significantly higher stone expulsion rate and shorter expulsion time in proximal UC ≤ 6 mm compared with conservative managements only. Our results indicate that similar to patients with distal UC, MET using tamsulosin is a reasonable treatment option for patients with proximal UC.

The effect of tamsulosin on pain and clearance according to ureteral stone location after shock wave lithotripsy

Background

Medical expulsion therapy has shown encouraging results in facilitating spontaneous clearance of ureteral stones after extracorporeal shock wave lithotripsy. However, no other study has yet determined the benefit of medical expulsion therapy for stones in different ureteral locations.

Objective

The aim of the study was to evaluate tamsulosin as adjunctive therapy to extracorporeal shock wave lithotripsy (SWL) in terms of pain clearance of stones in the upper, middle, and lower ureter.

Methods

Between June 2008 and July 2011, patients with a solitary ureteral stone that was ≥6 mm up to 15 mm and located in the upper, middle, or lower ureter undergoing SWL were evaluated. The patients were randomly allocated to a conservative treatment (group 1) and a tamsulosin treatment group (group 2). Administration of the drug was started immediately after SWL and was continued for a maximum of 28 days. Patients were evaluated for stone clearance, time to stone clearance, and number of SWL sessions. The pain intensity was evaluated by visual analog scale.

Results

There were 64 patients in the control group and 59 in the tamsulosin group. The average stone sizes were 10.70 (3.20) mm and 11.40 (3.01) mm (P = 0.24). Group 1 and group 2 received 2507 (984) and 2759 (775) shock waves (P = 0.86), 1.53 (0.8) and 1.49 (0.75) sessions (P = 0.85), respectively. Mean visual analog scale scores and times to clearance were 3.81 (2.74) and 2.73 (2.28) (P = 0.00) and 12.59 (8.63) days and 8.34 (7.60) days (P = 0.00), respectively, for all stones in groups 1 and 2. Only the clearance time of upper ureteral stones between groups showed statistical significance (13.54 [8.32] days vs 7.10 [6.40] days; P = 0.00).

Conclusions

Tamsulosin may help in the treatment of all ureteral stones after SWL, particularly stones in the upper ureter, with a shorter time to clearance and less need for analgesic drugs.

Comparing the efficacy of mydriatic cocktail-soaked sponge and conventional pupil dilation in patients using tamsulosin - a randomized controlled trial

BACKGROUND

A strong association exists between the use of tamsulosin and the occurance of intraoperative floppy iris syndrome. Several methods were advocated to overcome the progressive intraopertive miosis.Our purpose was to investigate the effect of a mydriatic-cocktail soaked cellulose sponge on perioperative pupil diameter in tamsulosin-treated patients undergoing elective cataract surgery.

METHODS

Patients using tamsulosin were dilated either with mydriatic-cocktail soaked sponge (group 1) or with conventional eyedrop regimen (group 2). Control patients not taking any α1 adrenergic receptor inhibtors were also dilated with mydriatic sponge (group 3).In all groups oxybuprocain 0.4%, cocain 4%, tropicamide 1%, phenylephrine 10%, diclophenac 0.1% along with chloramphenicol 0.5% were used preoperatively.Pupil diameter (mm) was measured preoperatively, after nucleus delivery, and before IOL implantation. Adverse effects associated with the use of sponge, minor and major intraoperative complications, the use of iris retractors and operation time were recorded.Differences in general between groups were analyzed with a one way analysis of variance (ANOVA); differences between groups in proportions were assessed by Fisher's exact test.

RESULTS

Mean pupil diameter (mm) was preopertively: 7.52 ± 1.21, 7.30 ± 1.55 and 7.99 ± 0.96 (ANOVA: p = 0.079); after nucleus delivery: 6 ± 1.20, 6.29 ± 1.12 and 6.52 ± 0.81 (ANOVA: p = 0.123); before IOL implantation: 5.46 ± 1.06, 5.83 ± 1.09 and 6.17 ± 0.89 (ANOVA: p = 0.0291).No adverse effect related to sponge use was detected. Frequency of minor complications, and iris hook use was similar in the two tamsulosin treated group. Operation time did not differ significantly in the three groups.

CONCLUSION

We have found that using a mydriatic cocktail-soaked wick - an alternative way to achieve intraoperative mydriasis for cataract surgery - was as effective and safe as the conventional repeated eyedrops regiment for tamsulosin treated patients.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN37834752.

5-HT1A receptor pharmacophores to screen for off-target activity of α1-adrenoceptor antagonists

The α1-adrenoceptors (α1-ARs), in particular the α1A-AR subtype, are current therapeutic targets of choice for the treatment of urogenital conditions, such as benign prostatic hyperplasia (BPH). Due to the similarity between the transmembrane domains of the α1-AR subtypes, and the serotonin receptor subtype 1A (5-HT1A-R), currently used α1-AR subtype-selective drugs to treat BPH display considerable off-target affinity for the 5-HT1A-R, leading to side effects. We describe the construction and validation of pharmacophores for 5-HT1A-R agonists and antagonists. Through the structural diversity of the training sets used in their development, these pharmacophores define the properties of a compound needed to bind to 5-HT1A receptors. Using these and previously published pharmacophores in virtual screening and profiling, we have identified unique chemical compounds (hits) that fit the requirements to bind to our target, the α1A-AR, selectively over the off-target, the 5-HT1A-R. Selected hits have been obtained and their affinities for α1A-AR, α1B-AR and 5-HT1A-R determined in radioligand binding assays, using membrane preparations which contain human receptors expressed individually. Three of the tested hits demonstrate statistically significant selectivity for α1A-AR over 5-HT1A-R. All seven tested hits bind to α1A-AR, with two compounds displaying K i values below 1 μM, and a further two K i values of around 10 μM. The insights and knowledge gained through the development of the new 5-HT1A-R pharmacophores will greatly aid in the design and synthesis of derivatives of our lead compound, and allow the generation of more efficacious and selective ligands.

Efficacy of alfuzosin after shock wave lithotripsy for the treatment of ureteral calculi

PURPOSE

We evaluated the efficacy of alfuzosin for the treatment of ureteral calculi less than 10 mm in diameter after extracorporeal shock wave lithotripsy (ESWL).

MATERIALS AND METHODS

A randomized, single-blind clinical trial was performed prospectively by one physician between June 2010 and August 2011. A total of 84 patients with ureteral calculi 5 to 10 mm in diameter were divided into two groups. Alfuzosin 10 mg (once daily) and loxoprofen sodium 68.1 mg (as needed) were prescribed to group 1 (n=41), and loxoprofen sodium 68.1 mg (as needed) only was prescribed to group 2 (n=44). The drug administration began immediately after ESWL and continued until stone expulsion was confirmed up to a maximum of 42 days after the procedure.

RESULTS

Thirty-nine of 41 (95.1%) patients in group 1 and 40 of 43 (93.0%) patients in group 2 ultimately passed stones (p=0.96). The number of ESWL sessions was 1.34±0.65 and 1.41±0.85 in groups 1 and 2, respectively (p=0.33). The patients who required analgesics after ESWL were 8 (19.5%) in group 1 and 13 (30.2%) in group 2 (p=0.31). Visual analogue scale pain severity scores were 5.33±1.22 and 6.43±1.36 in groups 1 and 2, respectively (p=0.056). The time to stone expulsion in groups 1 and 2 was 9.5±4.8 days and 14.7±9.8 days, respectively (p=0.005). No significant adverse effects occurred.

CONCLUSIONS

The use of alfuzosin in combination with ESWL seems to facilitate stone passage and to reduce the time of stone expulsion but does not affect the stone-free rate.

Cataract surgery in patients taking alpha-1 antagonists: know the risks, avoid the complications

BACKGROUND

The growing use of alpha-1 receptor antagonists in the treatment of benign prostatic hyperplasia (BPH) has created a new problem in ophthalmic surgery, the so-called intraoperative floppy iris syndrome (IFIS). This consists of a billowing iris, insufficient pupillary dilation with progressive intraoperative miosis, and protrusion of iris tissue through the tunnel and side port incision that are made for access to the anterior chamber during surgery. IFIS presents particular difficulties in cataract surgery which is carried out through the pupil with manipulations in the immediate vicinity of the iris. The complications range from poor visibility of the operative field to iris damage with the surgical instruments and to rupture of the posterior capsule, with loss of lens material into the vitreous body.

METHODS

Selective literature review.

RESULTS

Alpha-blockers have a direct effect on the alpha-receptors of the iris but also induce ultrastructural changes in the iridial stroma, leading to IFIS. The most important factor in avoiding complications of IFIS seems to be the ophthalmic surgeon's knowledge that the patient is taking an alpha-1 receptor antagonist.

CONCLUSION

A thorough medical history and an optimized information flow among all physicians treating the patient-the urologist, the family physician, and the ophthalmic surgeon-are essential for safe cataract surgery.

Outcomes and quality of life issues in the pharmacological management of benign prostatic hyperplasia (BPH)

BACKGROUND

Benign prostatic hyperplasia (BPH) is a common disease of the aging male population. BPH treatment includes a variety of pharmacological and surgical interventions. The goal of this paper is to review the natural history of BPH, outcomes of pharmacological management, effects on quality of life (QoL), future pharmacotherapies, and associated patient-focused perspectives.

MATERIALS AND METHODS

Medline searches for the keywords benign prostatic hyperplasia, BPH, alpha blockers, 5 alpha-reductase, and quality of life were performed. Relevant literature was reviewed and analyzed.

RESULTS

Alpha blockers, 5 alpha-reductase inhibitors, and phytotherapy are the three categories of pharmaceutical interventions currently available for BPH. Various clinical trials have shown that alpha blockers and 5 alpha-reductase inhibitors are safe, efficacious, and improve QoL in patients with BPH. The evidence for phytotherapeutics is not as convincing. The current armamentarium of pharmaceutical interventions are encompassed in these three classes of medications. New pharmacotherapies based on novel mechanisms are on the horizon.

CONCLUSION

There are a variety of safe and efficacious medical therapies available for the management of BPH and it is important for the practicing physician to have an understanding of these pharmacotherapies and their potential impact on the patient. There is not enough evidence to make a recommendation regarding phytotherapy use. New classes of drugs for BPH will likely find their way into routine use.

Ureteral motility

The pyeloureteral function is to transport urine from the kidneys into the ureter toward the urinary bladder for storage until micturition. A set of mechanisms collaborates to achieve this purpose: the basic process regulating ureteral peristalsis is myogenic, initiated by active pacemaker cells located in the renal pelvis. Great emphasis has been given to hydrodynamic factors, such as urine flow rate in determining the size and pattern of urine boluses which, in turn, affect the mechanical aspects of peristaltic rhythm, rate, amplitude, and baseline pressure. Neurogenic contribution is thought to be limited to play a modulatory role in ureteral peristalsis. The myogenic theory of ureteral peristalsis can be traced back to Engelmann (1) who was able to localize the peristaltic pressure wave's origin in the renal pelvis and suggested that the ureteral contraction impulse passes from one ureteral cell to another, the whole ureter working as a functional syncitium. Recent studies of ureteral biomechanics, smooth muscle cell electrophysiology, membrane ionic currents, cytoskeletal components and pharmacophysiology much improved our understanding of the mechanism of how the urine bolus is propelled, how this process is disturbed in pathological states, and what could be done to improve it.

Medical therapy of stone disease: from prevention to promotion of passage options

Medical therapy has been used for many years in the prevention of urinary stones. Medications directed at correcting urinary metabolic abnormalities responsible for promoting stone formation include thiazide diuretics, citrate salts, and allopurinol. All have proven to be efficacious. In addition, intake of citrate-rich juices, such as lemonade, may help to reduce urinary stone formation. More recently, there has been increasing interest in and use of medical therapy to aide in the passage of ureteral stones. Medical expulsive therapy (MET) has been shown to be cost effective compared with observation followed by treatment. Alpha-adrenergic receptor blockers are most commonly prescribed to promote passage of ureteral stones. They are able to facilitate stone passage, reduce time to passage, and decrease pain. Calcium-channel blockers also increase stone-passage rates. Steroids are useful adjuncts in MET.

Prospective randomized trial comparing efficacy of alfuzosin and tamsulosin in management of lower ureteral stones

OBJECTIVES

To study the efficacy of alfuzosin compared with tamsulosin in the management of lower ureteral stones.

METHODS

A total of 102 patients with stones <1 cm size and located in the lower ureter were enrolled in the present study and randomized into 3 equal groups. Group 1 patients (n = 34) received 0.4 mg tamsulosin daily, group 2 patients (n = 34) received 10 mg alfuzosin daily, and group 3 patients (n = 34) received placebo (control group). The patients were given 75 mg diclofenac injection intramuscularly on demand and were followed up for 4 weeks.

RESULTS

The average stone size for groups 1, 2, and 3 was comparable (6.17, 6.70, and 6.35 mm, respectively). Stone expulsion was observed in 28 of 34 patients (82.3%) in group 1, 24 of 34 patients (70.5%) in group 2, and 12 of 34 patients (35.2%) in group 3. The average expulsion time for groups 1, 2, and 3 was 12.3, 14.5, and 24.5 days, respectively. The results of both study groups (groups 1 and 2) were superior to those in the placebo group (P = .003 and P = .001, respectively), but the study failed to show any statistically significant differences between tamsulosin and alfuzosin (P = .25). Alfuzosin was associated with fewer side effects than tamsulosin, especially in terms of retrograde ejaculation.

CONCLUSIONS

Medical treatment of lower ureteral calculi with tamsulosin and alfuzosin resulted in a significantly increased stone expulsion rate, decreased expulsion time, and a reduced need for analgesic therapy.

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.

Alpha1-adrenoceptor subtypes and lower urinary tract symptoms

Benign prostatic hyperplasia (BPH) is a common cause of urinary outflow obstruction in aging men leading to lower urinary tract symptoms (LUTS). alpha(1)-Adrenoceptors (alpha(1)ARs) antagonists (blockers) have become a mainstay of LUTS treatment because they relax prostate smooth muscle and decrease urethral resistance, as well as relieving bladder LUTS symptoms. A review of key recent clinical trials suggests new insights into the role of specific alpha(1)AR subtypes in the treatment of LUTS.

Physiology and pharmacology of the human ureter: basis for current and future treatments

INTRODUCTION

This article sets out to be a review regarding agents that affect contraction and relaxation of the ureter in order to establish a basis for current and future treatments for upper urinary tract obstruction.

MATERIAL AND METHODS

A complete review of the English literature using MEDLINE was performed between 1960 and 2007 on ureter physiology and pharmacology with special emphasis on signal transduction mechanisms involved in the contractile regulation of the human ureter.

RESULTS

Activation of muscarinic and adrenergic receptors increases the amplitude of ureteral contractions. The sympathetic nerves modulate the contractions by alpha-adrenoceptors and relaxation by beta-adrenoceptors. The purinergic system is important in sensory/motor functions and ATP is an important non-adrenergic non-cholinergic (NANC) agent causing contraction. Nitric oxide (NO) is a major inhibitory NANC neurotransmitter causing relaxation. Serotonin causes contraction. Prostaglandin-F(2)alpha contracts whereas prostaglandin-E(1)/E(2) relaxes the ureter. Phosphodiesterases (PDE) and the Rho-kinase pathway have recently been identified in the human ureter. PDE-IV inhibitors, K(+) channel openers, calcium antagonists, alpha(1)-adrenoceptor antagonists and NO donors seem to be promising drugs in relieving obstruction and facilitating stone passage.

CONCLUSIONS

Further understanding of the ureteral function and pharmacology may lead to the discovery of promising new drugs that could be useful in relieving ureteral colic, facilitating spontaneous stone passage, preparing the ureter for ureteroscopy as well as acting adjunctive to extracorporeal shock-wave lithotripsy.

Improvement in Bladder Storage Function by Tamsulosin Depends on Suppression of C-Fiber Urethral Afferent Activity in Rats

PURPOSE

Alpha(1)-blockers improve voiding symptoms by decreasing prostatic and urethral smooth muscle tone. However, to our knowledge the mechanism underlying improvements in storage symptoms is not known. Topical application of prostaglandin E(2) to the rat lower urinary tract stimulates the micturition reflex. Using an animal model we investigated whether the alpha(1)-blocker tamsulosin (Astellas Pharma, Tokyo, Japan) acts on C-fiber afferent activity and, if so, the location of this effect.

MATERIALS AND METHODS

To induce desensitization of C-fiber afferent activity resiniferatoxin (0.3 mg/kg) was subcutaneously injected in female Sprague-Dawley rats 2 days before experiments. Simultaneous recordings of urethral pressure and rhythmic bladder pressure were made with the rats under urethane anesthesia. Prostaglandin E(2) (0.4 mg/ml) was continuously administered intravesically or intraurethrally to rats pretreated with resiniferatoxin (resiniferatoxin rats) or rats without pretreatment (nonresiniferatoxin rats). We investigated the effects on the micturition reflex of intravenous (2.2 x 10(-1) to 2.2 x 10(3) nM/kg) or intrathecal (0.001 to 0.1 nmol) administration of tamsulosin.

RESULTS

The bladder contraction interval was markedly decreased after intravesical or intraurethral administration of prostaglandin E(2) in nonresiniferatoxin rats but it was unchanged in resiniferatoxin rats. This effect was antagonized by the EP1 receptor antagonist ONO-8711 (6-[(2S,3S)-3-(4-chloro-2-methylphenylsulfonylaminomethyl)-bicyclo[2.2.2]octan-2-yl]-5Z-hexenoic acid). Intravenous administration of tamsulosin significantly increased the bladder contraction interval in nonresiniferatoxin rats receiving intraurethral prostaglandin E(2) but it had no effect on nonresiniferatoxin rats receiving intravesical prostaglandin E(2). Intrathecal administration of tamsulosin produced a slight and insignificant increase in the bladder contraction interval in nonresiniferatoxin rats receiving intraurethral prostaglandin E(2).

CONCLUSIONS

These results suggest that prostaglandin E(2) enhances the micturition reflex through C-fiber afferents and tamsulosin had an inhibitory effect on the C-fiber urethral afferent nerves, thereby improving bladder storage function.

Medical treatment of benign prostatic hyperplasia

Pharmaceutical preparations are commonly used for benign prostate hyperplasia. This article reviews the current understanding of the natural history of the condition and the literature regarding medical treatment.

α1-Adrenergic Receptor Antagonists and the Iris: New Mechanistic Insights into Floppy Iris Syndrome

Understanding the role of adrenergic receptors in iris biology has gained widespread interest due to the recently described intraoperative floppy iris syndrome sometimes encountered during cataract surgery. alpha(1)AR-mediated iris dilator smooth muscle contraction occurs via alpha(1a)ARs whereas alpha(1b)ARs mediate iris arteriolar contraction. Because alpha(1)AR antagonists are first-line therapy for benign prostatic hyperplasia and lower urinary tract symptoms, more elderly patients requiring cataract surgery now receive these drugs. After reviewing intraoperative floppy iris syndrome, strengths/weaknesses of supporting data, and reviewing iris biology, a case is made that rather than being drug specific (alpha(1)AR antagonists), intraoperative floppy iris syndrome may represent the "tip of the iceberg." Relaxed iris dilator muscle resistant to adrenergic agonists should be expected with clinical drugs shown to relax the iris dilator (e.g., antagonists at alpha(1)AR, endothelin-A, angiotensin receptors, nitric oxide donors such as nitrates), and/or diseases associated with endothelial dysregulation (e.g., congestive heart failure, diabetes, hypertension). Rather than a rare, unexpected, unpredictable syndrome due to one drug, a careful medical history should elucidate intraoperative floppy iris syndrome predisposition. Just as anticoagulants are discontinued prior to elective surgery, conservative management of elderly patients suggests discontinuation of drugs that relax iris dilator muscle, in consultation with the patient's primary physician, should be considered prior to cataract surgery.

Discontinuation of Tamsulosin Treatment in Men with Lower Urinary Tract Symptoms: A Pilot Study

OBJECTIVES

Since little investigation has been undertaken to determine if alpha1-blockers should be given continuously to sustain their efficacy, we conducted a pilot study to determine symptom change following discontinuation of tamsulosin after an initial improvement in symptoms in men with lower urinary tract symptoms (LUTS).

PATIENTS AND METHODS

Thirty-three of 78 patients with mild-to-moderate prostate hyperplasia, who had symptom improvement according to the International Prostate Symptom Score (IPSS) to <10 or the quality of life (QOL) index to < or =3 after initial treatment with tamsulosin, were enrolled in this study. Subjective parameters (IPSS and QOL index) and objective parameters (maximum and mean urinary flow rates) were evaluated at baseline and after initial treatment, and 4, 8, 12 and 24 weeks after discontinuing tamsulosin.

RESULTS

The rates of successful discontinuation of tamsulosin were high throughout the follow-up period, i.e., 80.6% at 4 weeks, 80.6% at 8 weeks, 80.0% at 12 weeks, and 68.9% at 24 weeks. Temporary worsening in both subjective and objective parameters was observed only at 4 weeks; however, these parameters recovered to almost post-treatment levels at 24 weeks.

CONCLUSION

The present study suggests that continuous treatment is not always needed to maintain urinary symptom relief in a specific subset of patients who felt symptom improvement after initial treatment with tamsulosin.

Safety and efficacy of tamsulosin in the treatment of painful ejaculation: a randomized, double-blind, placebo-controlled study

We evaluate the efficacy and safety of tamsulosin a selective alpha(1A)-receptor antagonist in patients with painful ejaculation (PE) as a sole entity. A total of 118 men with PE were included in the study. Patients were randomly assigned to receive 0.4 mg oral daily tamsulosin (group 1, n=59) or placebo (group 2, n=59), during a 6-week period for each agent. Pretreatment evaluation included history and physical examination, International Index of Erectile Function (IIEF) and a visual analog scale (VAS) for pain. The efficacy of two treatments was assessed every 2 weeks during treatment, and at the end of the study using responses to IIEF, VAS evaluation, mean intercourse satisfaction domain, mean weekly coitus episodes and adverse drug effects. In all, 104 patients (88%) completed the whole treatment schedule. Pain resolved in 16 and 13% of the patients treated with tamsulosin and placebo, respectively (P=0.1). Baseline mean intercourse satisfaction domain values of IIEF 10 and 11 reached to 12 and 10 at 6-week treatment in groups 1 and 2, respectively (P=0.08). The VAS after tamsulosin and placebo decreased from 5.7 and 5.8 to 5.1 and 5.5, respectively (P=0.1). The mean weekly intercourse episodes increased from pretreatment values of 1.8 and 1.6 to 1.9 and 1.7, for tamsulosin and placebo, respectively (P=0.08). Mean number of adverse events was 11 for tamsulosin and 5 for placebo (P<0.05). Tamsulosin is no better than placebo in improvement of PE as a sole entity.

Tamsulosin treatment increases clinical success rate of single extracorporeal shock wave lithotripsy of renal stones

OBJECTIVES

To design a randomized, no-treatment, controlled, prospective study to determine whether the administration of tamsulosin, as adjunctive medical therapy, increases the efficacy of one extracorporeal shock wave lithotripsy (ESWL) session to treat renal stones and decreases the use of analgesic drugs after the procedure.

METHODS

A total of 130 patients underwent a single ESWL session to treat solitary radiopaque renal stones 4 to 20 mm in diameter. After treatment, all patients were randomly assigned to receive our standard medical therapy alone (controls) or in association with 0.4 mg tamsulosin daily for a maximum of 12 weeks. All 130 patients were followed up for 3 months or until an alternative treatment was given.

RESULTS

Of the 130 patients, 78.5% of those receiving tamsulosin and 60% of controls had achieved clinical success at 3 months (P = 0.037). When we stratified patients according to stone size, for those with a stone size larger than 10 mm, the success rate was significantly greater in the tamsulosin group (P = 0.028). Renoureteral colic occurred in 76.9% of patients treated with standard therapy but in only 26.1% of those receiving tamsulosin (P < 0.001). The mean cumulative diclofenac dose was 375 mg per patient in the tamsulosin group and 675 mg per patient in the control group (P < 0.001).

CONCLUSIONS

The results of our study have demonstrated that tamsulosin therapy, as an adjunctive medical therapy after ESWL, is more effective than lithotripsy alone for the treatment of patients with large renal stones and is equally safe. In addition, our results also indicated that adjunctive treatment with tamsulosin could decrease the use of analgesic drugs after ESWL.

Treatment of benign prostatic hyperplasia in hypertensive men

As the proportion of the US population over the age of 65 continues to rise, it is likely that the number of individuals with concomitant benign prostatic hyperplasia and hypertension will also increase. To reduce morbidity and mortality, it is important to treat patients with hypertension optimally. Evidence from outcome trials suggests that alpha1 blockers should not be used as first-line antihypertensive therapy. Although some clinicians previously recommended alpha1 blocker monotherapy for patients with both hypertension and benign prostatic hyperplasia, the most recent American Urologic Association and Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure guidelines recommend independent treatment with the most appropriate pharmacologic agents for each condition. When treating patients with benign prostatic hyperplasia, clinicians should be aware of the potential impacts that alpha1 blockers may have on blood pressure and potential adverse events in patients who are normotensive as well as in patients with treated hypertension.

Alpha1 adrenoceptor subtypes in human urinary bladder: sex and regional comparison

A detailed study of the presence of alpha1 AR binding sites and alpha1 AR subtype mRNA expression in human urinary bladder areas involved in the micturition (i.e. detrusor, trigone and neck) is reported here, investigating whether or not there are differences between sexes. Results obtained indicated that alpha1 AR proteins were detectable in each bladder area. In both sexes, the detrusor and the neck expressed similar levels of alpha1 ARs: respectively, detrusor: 14.6 +/- 1.2 in men and 13.1 +/- 1.1 fmol/mg prot in women; neck: 16.9 +/- 3.2 in men and 17.5 +/- 4.1 fmol/mg prot in women. In the trigone, significantly higher alpha1ARs were found in women compared to men (20.6 +/- 1.1 vs 11.7 +/- 0.7 fmol/mg prot). Subtype analysis indicated that in women, each area was endowed with mRNA encoding for each alpha1 AR subtype. The men detrusor expressed alpha1a and alpha1d ARs, while in the trigone and the neck, each subtype was present. Since the detrusor muscle hypertrophy is a marker of bladder obstructive outlet, the selective alpha1 AR subtype targeting arouses much interest, as evidence indicates that there are differences in signalling pathways among the subtypes. Furthermore, the significance of the alpha1 ARs coexpression is still unknown; interestingly, recent papers demonstrate that alpha1 AR subtypes could dimerize. Thus, in the human urinary bladder it may be suggested a potential level of alpha1 AR complexity that could have an impact on drug development.

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.

Evaluation of tamsulosin and alfuzosin activity in the rat vas deferens: relevance to ejaculation delays

The effect of two alpha-adrenergic receptor antagonists widely employed in the therapy of benign prostatic hyperplasia, tamsulosin [(-)-(R)-5-[2-[[2-(0-ethoxyphenoxy) ethyl]amino]propyl]-2-methoxybenzenesulfonamide] and alfuzosin [(+/-)-N-[3-[(4-amino-6,7-dimethoxy-2-quinazolinyl) methylamino]propyl] tetrahydro-2-furancarboxamide], was investigated in the rat vas deferens. Because several clinical studies have shown that tamsulosin causes ejaculatory disorders, this study also evaluated the possible mechanisms implicated in these disorders by comparing the effect of tamsulosin with that of alfuzosin. Tamsulosin competitively antagonized the contractions induced by noradrenaline in vitro in the epididymal portion of the vas deferens with a potency pA(2) value of 9.2 +/- 0.8. In the prostatic portion, tamsulosin increased the amplitude of intermittent spikes induced by exogenous noradrenaline (100-1000 microM). In both portions of the vas deferens, alfuzosin behaved as an alpha-adrenergic antagonist blocking the contractions induced by exogenous noradrenaline without altering spikes. The administration of tamsulosin (3 microg/kg i.v.) significantly reduced the contractions evoked by electrical pulses in the epididymal portion, whereas it increased those produced in the prostatic portion. Intravenous tamsulosin antagonized the contraction produced by exogenous noradrenaline, whereas alfuzosin administration (10 microg/kg i.v.) did not change the electrically induced contractions in both portions of the rat vas deferens and did not antagonize the contractions produced by exogenous noradrenaline. The fact that tamsulosin unusually enhances noradrenaline-induced intermittent spike contractions and nerve stimulation-induced twitches in the prostatic portions might be linked to its greater propensity to cause sexual dysfunctions.