Topical and oral agents for erectile dysfunction.

Innovative research in the past 2 decades has shown that the hemodynamics of penile erection involve arterial dilation, sinusoidal expansion, and venous compression. Relaxation of the intracorporeal smooth muscles (trabecular and arteriolar) seems to be the final common pathway that leads to the above events. Neuropharmacologic studies have also established nitric oxide as the principal neurotransmitter for penile erection and confirmed the importance of cyclic adenosine monophosphate and cyclic guanosine monophosphate systems in penile smooth muscle relaxation. Recent years have also witnessed dramatic changes in the therapy of erectile dysfunction. The penile prosthesis, a gold standard of therapy of the 1970s, was replaced in the 1980s by the intracavernous injection and the vacuum constriction device. In the 1990s, two revolutionary concepts in erectile dysfunction therapy were added: transurethral alprostadil and oral sildenafil. However, the tremendous publicity surrounding the recent introduction of sildenafil has also created socioeconomic and ethical dilemmas, especially with regard to insurance coverage and government regulation. Medically, many problems also surfaced when large numbers of erectile dysfunction patients overwhelmed primary care physicians who were unfamiliar with the diagnosis and treatment of erectile dysfunction. This article reviews the advances in penile physiology and the clinical usefulness of topical and oral agents. In addition, a patients' goal-directed approach to the diagnosis and treatment of erectile dysfunction is presented.