Erectile dysfunction etiology

Differentiate between organic and psychogenic erectile dysfunction (ED) and describe the etiology and pathophysiology of each. 

Erectile dysfunction Treatment of erectile dysfunction caused by neurogenic, vasculogenic, psychogenic, or mixed etiology. 

Erectile dysfunction of vasculogenic, psychogenic, or mixed etiology - Do not give more than 2 doses within a 24-hour period during initial titration. If there is no response to the initial 2.5 meg dose, the second dose may be increased to 7.5 meg within 1 hour. If additional titration is required, doses in increments of 5 to 10 meg may be given at least 24 hours apart. 

Current Drugs. Several pharmacological agents are available for the treatment of erectile dysfunction with different etiologies, which makes the condition treatable in the vast majority of sufferers. Table 9.8 lists the pharmacotherapeutic agents currently approved for erectile dysfunction. 

Although phosphodiesterase inhibitors are convenient and effective regardless of the etiology of erectile dysfunction, they fail in 30% to 40% of patients. Also, phosphodiesterase inhibitors are contraindicated in patients taking any form of nitrate, including topical nitrates. 

Although intracavernosal alprostadil injections are effective independent of the etiology for erectile dysfunction, these fail in one-third of patients. Also, they should be used cautiously in patients at risk of priapism, which includes those with sickle cell disease or lymphoproliferative disorders. 

Erectile dysfunction can result from any single abnormality or combination of abnormalities of the four systems necessary for a normal penile erection. Vascular, neurologic, or hormonal etiologies of erectile dysfunction are collectively referred to as organic erectile dysfunction. About 80% of patients with erectile dysfunction have the organic type. Patients who fail to respond to psychogenic stimuli have psychogenic erectile dysfunction. 

With the availability in the late 1990s of effective medications for erectile dysfunction independent of the etiology, diagnostic evaluation of erectile dysfunction became streamlined. " Key assessments include a description of the severity of the erectile dysfunction, a medical history, a review of concurrent medications, a physical examination, and selected clinical laboratory tests. ... 

In the presence of sexual stimulation and in doses of 25 to 100 mg, sildenafil produces satisfactory erections in 56% to 82% of patients, independent of the etiology of erectile dysfunction. Similar values are documented in the product labeliug for the other two agents in this class (65% to 80% for vardenafll and 62% to 77% for tadalafil). Response rates for sUdenafll in the lower range have been documented in patients following radical prostatectomy, probably due to postoperative nerve damage. The drugs effectiveness appears to be dose related. °... 

Basar M, Tekdogan UY, Yilmaz E et al (2001) The efficacy of sildenafil in different etiologies of erectile dysfunction. Int Urol Nephrol 32 403-407... 

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