Comparative tolerability and efficacy of treatments for impotence

Modern pharmacological treatment of impotence is determined by the presenting symptoms. Since this involves symptomatology with a heterogenous aetiology, many different drugs are involved in the treatment of impotence. Drugs used for libido and arousal problems include testosterone, yohimbine, trazodone and apomorphine. Since patient self-assessment is the only parameter that can be used to measure the result of treatment and positive results are seldom affirmed, no positive benefit of these agents can be assumed at present. Oral medications for erectile dysfunction include yohimbine, trazodone, apomorphine, phentolamine, arginine and sildenafil. Of these drugs, sildenafil has been the most systematically studied for effectiveness, but long term safety data await the results of post-marketing surveillance. Of the ejaculation disorder therapies, treatments for premature ejaculation are the best studied. Favourable results have been obtained with clomipramine, paroxetine and fluoxetine. The safety of these medications has been assessed through their long term use in psychiatry. Intracavernous self-injections for erectile disorders are performed using a variety of drugs and drug mixtures. Only alprostadil and the combination of papaverine with phentolamine are widely used. Alprostadil is very well tolerated; however, penile pain is a serious problem in a significant proportion of patients. Papaverine in combination with phentolamine is effective, but penile fibrosis and priapism occur more often than with the use of alprostadil. Several new developments in this area are currently under way. Alternative routes for medication for erectile dysfunction include ointments and patches to the penile skin and the glans. Only transurethral alprostadil, 'MUSE' (medicated urethral system for erection) has been shown to be effective in large trials. Long term safety still has to be demonstrated, but the 1-year safety profile is encouraging. In general, the end points of impotence treatment studies are very diverse so efficacy data can only be assessed in comparative studies. However, long term comparison studies have not been performed. Safety demands must be set very high for this type of treatment since the disorders being treated present no threat to the patient's health.