Comparison of the antagonistic activity of tamsulosin and doxazosin at vascular alpha 1-adrenoceptors in humans

Effects of percutaneous angioplasty on kidney function and blood pressure in patients with atherosclerotic renal artery stenosis

Background

Previous randomized controlled trials of revascularization for atherosclerotic renal artery stenosis (ARAS) were not successful. We investigated the effects of percutaneous transluminal angioplasty with stent insertion (PTA/S) on kidney function and blood pressure (BP) control in patients with ARAS.

Methods

From 2000 to 2017, 47 subjects who underwent PTA/S for ARAS were identified. A high-risk group was defined, composed of patients having one or more of the following clinical presentations: pulmonary edema, refractory hypertension, and rapid deterioration of kidney function. Subjects who met the criteria of 'kidney function improvement' or 'hypertension improvement' after PTA/S were classified as responders.

Results

Twenty-one (44.7%) subjects were classified into the high-risk group. Two subjects (8.0%) in the low-risk group (n = 25) and 5 subjects (27.8%) in the high-risk group (n = 18) showed improvement in kidney function after PTA/S (P = 0.110). In patients with rapid decline of kidney function, estimated glomerular filtration rate improved from 28 (interquartile range [IQR], 10-45) mL/min/1.73 m² to 41 (IQR, 16-67) mL/min/1.73 m² at 4 months after PTA/S, although the difference was not significant (P = 0.084). Regarding BP control, 9 (36.0%) and 14 (77.8%) subjects showed improvement after PTA/S in the low- (n = 25) and high-risk (n = 18) groups, respectively (P = 0.007). In patients with refractory hypertension, the systolic BP dropped from 157 (IQR, 150-164) mmHg to 140 (IQR, 131-148) mmHg at 4 months after PTA/S (P = 0.005). Twenty-five subjects were defined as responders and comprised a significant proportion of the high-risk group (P = 0.004).

Conclusion

PTA/S might improve BP control and kidney function in patients with ARAS presenting with high-risk clinical features. The optimal application of PTA/S should be based on individual assessment of the clinical significance of renal artery stenosis.

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.

Tamsulosin: a review of its pharmacology and therapeutic efficacy in the management of lower urinary tract symptoms

Tamsulosin is a subtype-selective alpha(1A)- and alpha(1D )-adrenoceptor antagonist. alpha(1)-Receptors predominate in the prostate gland, prostatic capsule, prostatic urethra and bladder, and the relaxation of prostate and bladder smooth muscles is associated with improved maximal urine flow (Q(max)) and alleviation of lower urinary tract symptoms (LUTS) in patients with benign prostatic hyperplasia (BPH). Tamsulosin 0.4 mg once daily in a modified-release formulation increased Q(max) and improved symptom scores relative to baseline to a greater extent than placebo in 12- and 13-week double-blind, randomised, multicentre, clinical trials in patients with LUTS, with statistical significance between treatments for Q(max) values in two of three published US and European studies. Tamsulosin is effective in patients with mild to severe LUTS associated with BPH, in patients with diabetes mellitus and in the elderly, and does not interfere with concomitant antihypertensive therapy. Pooled data based on patients receiving tamsulosin 0.4 or 0. 8mg once daily indicate maintenance of efficacy for up to 6 years. Tamsulosin 0.4 mg once daily was of similar efficacy to alfuzosin 2.5 mg three times daily, with less tendency to cause hypotensive effects, in a double-blind, randomised 12-week trial. Benefit of the drug has also been shown in patients with acute urinary retention or chronic abacterial prostatitis, those receiving high energy transurethral microwave thermotherapy, and in patients with prostate cancer with radiation-induced urethritis. Dizziness and abnormal ejaculation are stated to be the most common adverse events, with asthenia, postural hypotension and palpitations being seen less frequently (1 to 2% incidence), in patients receiving tamsulosin 0.4 mg once daily. Tamsulosin has not been associated with clinically significant changes in blood pressure in clinical trials.

CONCLUSION

The alpha(1A)- and alpha(1D)-adrenoceptor antagonist tamsulosin, given at a dosage of 0.4 mg once daily in a modified-release formulation, is effective and well tolerated in the treatment of LUTS associated with BPH. Although the drug has been directly compared to date with one other agent only, data show overall that tamsulosin clearly offers advantages over other alpha(1)-adrenoceptor antagonists in terms of the need for a single daily dose only, and its low potential for hypotensive effects or interference with concomitant antihypertensive therapy. Dosage titration at the start of treatment is not necessary. Tamsulosin has a rapid onset of action and is effective in patients with moderate or severe symptoms. The drug is therefore a valuable therapeutic option, with both demonstrated and potential advantages over older nonselective agents, in the management of patients with LUTS associated with BPH.

Tamsulosin: an update of its role in the management of lower urinary tract symptoms

Tamsulosin is a selective alpha1A- and alpha1D-adrenoceptor antagonist. These alpha1-receptors are predominant in the prostate, prostatic capsule, prostatic urethra and bladder. The relaxation of prostate and bladder smooth muscles may result in improvement in maximum urine flow (Qmax) and reduction of lower urinary tract symptoms (LUTS). Tamsulosin 0.4 and 0.8 mg/day in a modified-release formulation was significantly more effective than placebo in large (n >250) double-blind, randomised, multicentre, 12- to 13- week clinical trials in patients with LUTS. A greater increase in Qmax from baseline was seen in patients receiving tamsulosin 0.4 or 0.8 mg/day (1.4 to 1.79 ml/sec from a baseline of 9.46 to 10.7 ml/sec) than in placebo recipients (0.4 to 0.93 ml/sec from a baseline of 9.75 to 10.4 ml/sec); the between-group difference was significant in two of three studies. Tamsulosin 0.4 or 0.8 mg/day improved total Boyarsky symptom scores from baseline by a significantly greater extent (by 3.0 to 5.2 points from a baseline of 9.5 to 11.1 points) than placebo (1.9 to 3.2 points from a baseline of 9.3 to 11.0 points). In noncomparative extension studies, the improvement in efficacy parameters with tamsulosin treatment was maintained for up to 4 years. Tamsulosin is effective in patients with mild to severe LUTS, patients with diabetes mellitus or those aged > or = 65 years and does not interfere with the antihypertensive action of nifedipine, enalapril or atenolol. Tamsulosin 0.4 mg/day for 12 weeks and tamsulosin 0.2 mg/day for 4 weeks were as effective as alfuzosin 2.5mg three times daily and terazosin 2 mg/day, respectively, in improving Qmax and symptom scores in randomised comparative trials. With the exception of a numberically greater incidence of abnormal ejaculation, dizziness and rhinitis, the incidence of adverse events with tamsulosin 0.4 mg/day was similar to that seen with placebo in randomised, double-blind studies. The overall incidence of symptoms indicative of orthostasis was 1.4% with tamsulosin 0.4 or 0.8 mg/day treatment. Tamsulosin had less effect on blood pressure than alfuzosin or terazosin.

CONCLUSION

Tamsulosin, an alpha1-adrenoceptor antagonist, has a well established place in the treatment of LUTS and has a tolerability profile similar to that of placebo (apart from a higher incidence of abnormal ejaculation, dizziness and rhinitis). Comparative data have shown tamsulosin to be as effective as other alpha1-adrenoceptor antagonists at increasing Qmax and improving symptom scores. However, tamsulosin is unlikely to produce orthostatic hypotensive adverse effects or interfere with concomitant antihypertensive drug therapy. Therefore, tamsulosin is a useful therapeutic option in the management of patients with moderate to severe LUTS.

Yohimbine: a clinical review

Although yohimbine (YOH) has been available for the treatment of male erectile dysfunction (ED) for longer than Viagra, there is a perception that little is known about the clinical performance of the drug. This review attempts, by comprehensive analysis of the literature, to cover the clinical, pharmacological, and therapeutic profiles of YOH, relevant to its potential utility in the management of patients with ED. Relatively few well-designed studies have been completed. From these, however, it can be concluded that YOH as monotherapy possesses only modest efficacy in ED patients. In acute and chronic (long-term) studies, YOH has been found to be relatively free of side effects over the dose range predicted to be effective in ED. At much higher doses, the most frequently observed effects, consistent with the primary pharmacological action of the drug, are elevation of blood pressure, a slight anxiogenic action, and increased frequency of urination. These side effects are all easily reversible on termination of YOH therapy. There is increasing evidence that the erectogenic action of YOH can be augmented by concomitant administration of agents that augment the release and/or action of nitric oxide in the corpus cavernosum. YOH has yet to be studied in female sexual dysfunction. Overall, the benefit risk profile of YOH would indicate that it has potential, more probably as part of a combination strategy, e.g., with a drug that enhances the nitric oxide pathway, in the treatment of ED.

Differential vascular alpha1-adrenoceptor antagonism by tamsulosin and terazosin

AIMS

In patients with lower urinary tract symptoms suggestive of benign prostatic obstruction the alpha1-adrenoceptor antagonist terazosin lowers blood pressure whereas only very small if any alterations were reported with the alpha1-adrenoceptor antagonist tamsulosin. Therefore, we have compared the vascular alpha1-adrenoceptor antagonism of tamsulosin and terazosin directly.

METHODS

Ten healthy subjects were investigated in a randomized, single-blind, three-way cross-over design and received a single dose of 0.4 mg tamsulosin, 5 mg terazosin or placebo on 3 study days at least 1 week apart. Before and 1, 3, 5, 7, 10 and 23.5 h after drug intake, alterations of diastolic blood pressure and other haemodynamic parameters in response to a graded infusion of the alpha1-adrenoceptor agonist phenylephrine were determined non-invasively.

RESULTS

At most time points tamsulosin inhibited phenylephrine-induced diastolic blood pressure elevations significantly less than terazosin (5 h time point: median difference in inhibition 35%, 95% CI: 18.7-50.3%). On the other hand, phenylephrine-induced changes of cardiac output, heart rate and stroke volume were similar during both active treatments.

CONCLUSIONS

In doses equi-effective for treatment of lower urinary tract symptoms tamsulosin causes less inhibition of vasoconstriction than terazosin.