MUSE: clinical experience

The Use of Vasoactive Drugs in the Treatment of Male Erectile Dysfunction: Current Concepts

It is widely accepted that disorders of the male (uro)genital tract, such as erectile dysfunction (ED) and benign diseases of the prostate (lower urinary tract symptomatology or benign prostatic hyperplasia), can be approached therapeutically by influencing the function of both the vascular and non-vascular smooth muscle of the penile erectile tissue or the transition zone/periurethral region of the prostate, respectively. As a result of the discovery of nitric oxide (NO) and cyclic guanosine monophosphate (GMP) as central mediators of penile smooth muscle relaxation, the use of drugs known to increase the local production of NO and/or elevate the intracellular level of the second messenger cyclic GMP have attracted broad attention in the treatment of ED of various etiologies. Specifically, the introduction of vasoactive drugs, including orally active inhibitors of the cyclic GMP-specific phosphodiesterase (PDE) 5, has offered great advantage in the pharmacotherapy of ED and other diseases of the genitourinary tract. These drugs have been proven efficacious with a fast on-set of action and an improved profile of side-effects. This review summarizes current strategies for the treatment of ED utilizing the application of vasoactive drugs via the oral, transurethral, topical, or self-injection route.

Erectile dysfunction: a need for greater awareness

Research has led to effective treatment regimes for erectile dysfunction (ED). Convincing evidence links vascular risk factors (hypertension, diabetes mellitus, hyperlipidaemia and smoking) with ED. This association is not surprising since the corpus cavernosum is a modified vascular tissue. This review presents a brief account of the aetiology, diagnosis and treatment of ED. There is a need to raise awareness of this condition and to make appropriate treatment available to patients.

Prostaglandin E1 for treatment of erectile dysfunction

BACKGROUND

Erectile dysfunction (ED), the inability to achieve or maintain an erection sufficient for satisfactory sexual activity, is one of the most common sexual dysfunctions in men. ED may have a dramatic impact on the quality of life of many men and their partners.

OBJECTIVES

The aim of this systematic review was to evaluate and summarise the effectiveness and safety of PGE1 in the treatment of erectile dysfunction.

SEARCH STRATEGY

We searched the Cochrane MS Group Trials Register (June 2003), the Cochrane Central Register of Controlled Trials (issue 2, 2003), MEDLINE (January 1966 - June 2003), EMBASE (January 1988 - June 2003) and reference lists of articles. We also undertook handsearching and contacting trialists and pharmaceutical companies.

SELECTION CRITERIA

All unconfounded, double blind, randomised controlled trials comparing PGE1 and placebo treatment in participants with ED of different aetiology were considered. Primary outcomes were: (a) patient and partner satisfaction measured by means of a self-assessment; (b) quality of life and (c) safety assessment. Both parallel group and cross-over design trials were considered for inclusion.

DATA COLLECTION AND ANALYSIS

All the reviewers independently selected articles for inclusion, assessed the trials' quality and extracted the data. Study authors were contacted for additional information.

MAIN RESULTS

Four trials involving 1.873 people, heterogeneous with respect to aetiology of ED, were included. Study design was two cross-over and two parallel group trials. Only the latter provided adequate data for meta-analyses. PGE1 was effective during follow-up in the "at least one successful intercourse" outcome (Peto Odds Ratio, OR 7.22, 95% CI. 5.68-9.18) and "number of successful intercourse/number of PGE1 administrations" (Peto Odds Ratio, OR 6.46, 95% CI. 5.95-7.01). One cross-over study reported "at least one successful intercourse" in 63.6% of participants with at least one dose of PGE1 (P < 0.01 for each active dose versus placebo). In the other cross-over study, only one of three treatment groups conducted a self-evaluation (55.5%: "good" or "excellent" response). Adverse effects were most frequent in the treated groups and occurred more often and intensely as doses increased. Penile pain (Peto OR 7.39, 95% CI. 5.40-10.12) and minor urethral trauma (Peto OR 3.79, 95% CI. 1.88-7.65) were predominant.

REVIEWERS' CONCLUSIONS

PGE1 was beneficial for many participants with ED of different aetiology. Adverse effects were proportional to dosage, albeit never serious. The use of PGE1 in ED could have been better interpreted if its effectiveness were compared by aetiology and with different forms of administrations, a longer follow-up were considered and more emphasis given to patient/partner relationships and quality of life.

Sildenafil in erectile dysfunction: a critical review

Sildenafil citrate (Viagra) is a potent orally active cGMP-specific phosphodiesterase type 5 (PDE5) inhibitor that is effective as a peripheral conditioner in the treatment of male erectile dysfunction (ED) of organic, psychogenic or mixed aetiology. Sildenafil is the first effective oral agent in the management of ED that has had a revolutionary impact on management of ED. The present review has been subdivided into five major sections. Based on the most recent peer-reviewed publications, the first section is aimed at critically evaluating PDE5 selectivity as well as the pharmacokinetics and pharmacodynamics of the drug, mainly to assess the best doses for each group of patients (i.e. adult and elderly men). Effectiveness in a broad spectrum ED population is the subject of the second section of the review, principally reporting post-marketing company-independent results. Safety and tolerability are the key concerns of the third section, with a broad consideration of the most commonly reported adverse events. Special attention has been paid to the cardiovascular safety of the drug, chiefly outlining the positive and potentially protective cardiac effects of sildenafil. Moreover, the impact of sildenafil in special patient populations is considered, namely in men complaining of diabetes mellitus, depression, neurological disorders, renal failure and those who have undergone a radical prostatectomy. Sildenafil and the ageing male has been especially underlined. Finally, the review covers a few new potential applications of sildenafil in ED patients with regard to high-dose treatment and combination therapy. The review ends with several considerations regarding the direct and/or indirect impact of sildenafil over quality of life and quality of partnership.