Erectile Dysfunction: Update and Options in Primary Care.

THE PHYSIOLOGICAL MECHANISMS of erections include neural initiation of penile erection following erectogenic stimuli, cellular activation of smooth muscle relaxation, and smooth muscle relaxation in the corpus cavernosum of the penis. Therefore, treatment strategies may be designed to operate at one or more of these pathways, with the least invasive methods being preferable as first-line therapy. As therapy is developed to be less invasive, such as oral therapy, it naturally becomes more of a systemic therapy. Thus, side effects that may be associated with the medication and other effects on the body must be taken into consideration. One of the frequently ignored first-line therapies for erectile dysfunction that is also least invasive is the vacuum therapy. Initial treatment should address psychogenic factors, and attempts should be made to identify and eliminate modifiable risk factors such as alcohol and cigarette consumption.

Local therapies include noninvasive vacuum devices, minimally invasive treatments such as intracavernosal injections and transure thral suppositories, and invasive surgical procedures such as penile prosthesis implantation, penile artery bypass, and venous ligation. The advantages and disadvantages of each local treatment should be considered in the context of the specific patient and his relationship with his sexual partner.

Sildenafil, an oral medication, acts at the cellular level to increase smooth muscle relaxation in the corpus cavernosum during sexual stimulation by the inhibition of phosphodiesterase type 5 (PDE5). In clinical studies, 60% to 65% of men with erectile dysfunction (ED) at baseline reported an improvement in erections in response to a sexual function questionnaire. Second generation phosphodiesterase inhibitors are in the midst of clinical trials in the United States.

In contrast, the erectogenic effects of apomorphine HC1, administered as a sublingual tablet, are mediated at dopamine receptors in the hypothalamus and mid-brain. In clinical studies, 50% to 55% of men with ED at baseline were able to achieve erections firm enough for sexual intercourse within 15 to 25 minutes following administration of apomorphine. Another new unique therapy that is less invasive is the development of a topical delivery of a previously successful agent in the management of erectile dysfunction as injection therapy. That agent is prostaglandin-El. Studies for FDA approval have been performed in the United States for this topical agent with the apparent advantage of an absorption enhancer in this new product.

From the Department of Urology, Medical College of Georgia, Augusta, Ga.