NOCTURNAL PENILE TUMESCENCE ACTIVITY UNCHANGED AFTER LONG-TERM INTRACAVERNOUS INJECTION THERAPY

Pharmacology and perspectives in erectile dysfunction in man

Penile erection is a perfect example of microcirculation modulated by psychological factors and hormonal status. It is the result of a complex neurovascular process that involves the integrative synchronized action of vascular endothelium; smooth muscle; and psychological, neuronal, and hormonal systems. Therefore, the fine coordination of these events is essential to maintain penile flaccidity or allow erection; an alteration of these events leads to erectile dysfunction (ED). ED is defined as the consistent or recurrent inability of a man to attain and/or maintain a penile erection sufficient for sexual activity. A great boost to this research field was given by commercialization of phosphodiesterase-5 (PDE5) inhibitors. Indeed, following the discovery of sildenafil, research on the mechanisms underlying penile erection has had an enormous boost, and many preclinical and clinical papers have been published in the last 10 years. This review is structured to provide an overview of the mediators and peripheral mechanism(s) involved in penile function in men, the drugs used in therapy, and the future prospective in the management of ED. Indeed, 30% of patients affected by ED are classified as "nonresponders," and there is still an unmet need for therapeutic alternatives. A flowchart suggesting the guidelines for ED evaluation and the ED pharmacological treatment is also provided.

Investigations in erectile dysfunction

PURPOSE OF REVIEW

This is an update of recent developments in the investigation of erectile dysfunction in the period since March 2002.

RECENT FINDINGS

Three developments in the field of medical sexology redirected the approach towards the investigation of erectile dysfunction. First, the emergence of oral pharmacological therapy; second, the notion that sexual relationship issues have an important impact on the successful outcome of pharmacological therapy; and finally, the concept that erectile dysfunction is often a sequel or even a sentinel of cardiovascular disease. Consequently, the current evaluation of men with erectile dysfunction may be divided into two steps: a basic diagnostic evaluation for the majority of men, and specific diagnostic procedures for a small minority. The basic evaluation is aimed at the identification of the underlying pathological condition and erectile dysfunction-associated risk factors. Such screening may diagnose reversible causes of erectile dysfunction and also unmask medical and psychological conditions that manifest with erectile dysfunction. The basic evaluation consists of a comprehensive medical, sexual and psychosocial history and a physical examination. Patients who have failed first-line treatment or complicated cases qualify for specific diagnostic procedures, traditionally performed by urologists.

SUMMARY

Current research into the investigation of erectile dysfunction emphasizes the notion that erectile dysfunction is often a result of an interplay between medical and psychosexual conditions. Recognition of the underlying conditions and an estimation of their relative contribution to the patient's and his partner's sexual problem are key issues in the current evaluation of the man with erectile dysfunction.

Pharmacological management of erectile dysfunction

Erectile dysfunction (ED) is a common medical condition that affects the sexual life of millions of men worldwide. Many drugs are now available for treating ED; oral pharmacotherapy represents the first-line option for most patients with ED. Sildenafil, an inhibitor of the enzyme phosphodiesterase type 5, is currently the most widely prescribed oral agent and has a very satisfactory efficacy-safety profile in all patient categories. Apomorphine SL is a dopamine D1- and D2-receptor agonist which has recently been approved for marketing in Europe. It is best selected for treating patients with mild to moderate ED. Vardenafil and tadalafil are new phosphodiesterase type 5 inhibitors which are expected to be approved this year. Both of them have significant positive efficacy-safety profiles. Patients who do not respond to oral pharmacotherapy or who cannot use it are good candidates for intracavernosal and intraurethral therapy. Alprostadil is the most widely used drug, both for injection therapy and for the intraurethral route. The efficacy of second-line treatment is high but the attrition rate remains significant.

Intracavernous injections for erectile dysfunction in patients with cardiovascular diseases and failure or contraindications for sildenafil citrate

The aim of this study was to evaluate the effectiveness of a progressive program for the treatment of erectile dysfunction in patients with cardiovascular disease in whom sildenafil citrate (Viagra) was not an option. The study population included 106 patients selected from 267 with cardiovascular disease. The intracavernous injection program consisted of three protocols of increasingly complex combinations of vasoactive drugs, papaverine, phentolamine, prostaglandin E1 and atropine sulfate. Patients who failed the first protocol were switched to the second, and those who failed the second were switched to the third. A positive response was defined as an erection sufficient for vaginal penetration. A positive response was achieved on protocol I in 61 of the 106 patients (57.5%); protocol II in 32 of the remaining 45 patients (71.1%); and protocol III in seven of the remaining 13 patients (53.8%); the total success rate was 94.3%. These 100 patients were included in the 1-year follow-up, and 90 reported successful coitus at the end of that period: 79 patients (87.8%) with intracavernous injection and 11 (12.2%) without injection. The remaining 10 patients (10%) dropped out of the program, seven (7.0%) for health or marital reasons and three (3.0%) because of treatment failure. We conclude that a progressive program of intracavernous injections of vasoactive drugs may be a good alternative for the treatment of erectile dysfunction in patients with cardiovascular disease.