INTRACAVERNOUS PHARMACOTHERAPY

Intracavernous application of vasoactive substances not only has enhan ced our understanding of penile hemodynamics, the physiology of penile erection, and the pathophysiology of erectile dysfunction but also ha s revolutionized the diagnosis and treatment of erectile dysfunction i n the last 15 years. Virag was the first to report on the erectile eff ect of papaverine in humans, and Brindley later reported the effect of intracavernous application of alpha-receptor-blocking agents on caver nous tissue. These reports led to numerous basic and clinical investig ations and ultimate:ly established a new treatment alternative for pat ients with erectile dysfunction that is now considered to be the treat ment of choice for most patients. Changes in penile hemodynamics inclu de the relaxation of cavernous smooth musculature and arteries, which leads to an increase in arterial blood flow and a restriction of venou s outflow through a compression of subtunical veins. These hemodynamic changes are the prerequisite for the induction and maintenance of pen ile erection. With the intracavernous application of vasoactive substa nces it was possible to influence penile hemodynamics at a local level and to induce an erection despite alterations in the nervous system, penile arterial blood flow, cavernous musculature, or neurotransmitter status. In addition, the local application of pharmacologically activ e substances directly to the end organ enabled the achievement of high local drug concentrations without severe systemic side effects. The c ommonly used substances are papaverine, the combination of papaverine and phentolamine, and prostaglandin E1 (alprostadil). In addition to t hese established substances, several other regimens, such as linsidomi ne (SIN-1), calcitonin gene-related peptide (CGRP), moxisylyte, and va rious triple- or quadruple-drug mixtures have been described. In addit ion, several other compounds as well as different routes of administra tion are on the horizon and may prove to be effective in the future di agnosis and treatment of erectile dysfunction.