Erectile dysfunction: management update

Abstract

E rectile dysfunction can be defined as the inability to achieve or maintain a penile erection sufficient for satisfactory sexual performance. 1 In the face of an aging population, decreasing social stigma associated with erectile dysfunction and an increasing availability of effective oral therapy for its treatment, the number of patients presenting with this complaint has increased dramatically. Current estimates describe 2-3 million Canadian men as having significant recurring erectile difficulties. Recent reports identifying a dramatic increase in rates of diabetes, increased longevity and higher quality-of-life expectations by "baby boomers" are all believed to be factors in a projected continued expansion of the patient population requesting medical help with sexual issues in the near future.2,3 Although historically erectile dysfunction was a problem identified and treated by urologists, today primary care physicians and other specialists write 80% of the prescriptions for sildenafil, the most popular drug used to treat the condition. 4 In this article, we review the epidemiology of erectile dysfunction, the current understanding of its pathophysiology and the evidence for the efficacy of oral therapy with phosphodiesterase type-5 inhibitors, which has become the first-line treatment of erectile dysfunction. Epidemiology of erectile dysfunctionThe Massachusetts Male Aging Study surveyed 1709 men aged 40-70 years in the greater Boston area between 1987 and 1989 and reported a prevalence of erectile dysfunction of 52%, with 9.6% of respondents reporting complete erectile dysfunction. 5 In 2000 the overall prevalence of erectile dysfunction in this study population was reestimated to be 44%. 6 The Massachusetts study is important because it is the first cross-sectional, communitybased, random-sample multidisciplinary survey on the topic and involved a significant cohort followed up for nearly a decade beyond the initial assessment. A survey of 3009 men aged 18-70 years from all regions of Canada revealed a similar prevalence of erectile dysfunction. 7 Physiology of an erectionErection involves the integration of neural and vascular functions. In essence, an erection occurs when blood flow to the penis exceeds flow out of the penis. The cavernosal arteries supply blood to the corpora cavernosa of the penis (through the pudendal artery); the emissary veins running through the tunica albuginea allow drainage. During erection, relaxation of trabecular smooth muscle results in increased blood flow to the corpora cavernosa and expansion of the sinusoids therein. This distension causes mechanical compression of the emissary veins, which impedes their ability to drain blood and thereby results in penile rigidity 8 (Fig. 1).Penile blood flow is controlled by the autonomic erection centre, which provides parasympathetic (S 2 -S 4 ) and sympathetic (T 12 -L 2 ) input to the pelvic plexus, 8 including the cavernous nerves that innervate the cavernosal arteries and trabecular smooth muscle. These nerves are responsible f...

Differential Effects of the Phosphodiesterase Type 5 Inhibitors Sildenafil, Vardenafil, and Tadalafil in Rat Aorta

“…Thus, the present results are in good agreement with the data reported using purified PDE5 . The longer lasting clinical effects of tadalafil might be related to different pharmacokinetic properties like slower absorption and/or degradation (Fazio and Brock, 2004).…”

Application of Cardiac Autonomous Indices in the Study of Neurogenic Erectile Dysfunction

“…The sympathetic and parasympathetic nerves merge from the neurons in the spinal cord and peripheral ganglia to form the cavernous nerves, which enter the corpora cavernosa and corpus spongiosum to affect the neurovascular events during erection and detumescence. The sensation and the contraction of the bulbo-and ischiocavernosus muscles are assured by the somatic nerves [4].…”

“…Clinical studies show that erectile dysfunction may be caused by a variety of factors: psychogenic, arteriogenic, neurogenic, endocrinologic, and cavernosal, based on the organs that are involved in penile erection. Amongst them, neurogenic erectile dysfunctions are an important group of organic etiologies probably because a deficiency of neurotransmitters is the final common pathway in many diseases and conditions [1,3,4].…”

Diagnosing erectile dysfunction could save your patient’s life

“…Beta-adrenergic blocking agents, thiazide diuretics and spironolactone can also contribute to ED. 3 Smoking can also contribute to ED by inducing vasoconstriction and penile venous leakage due to its contractile effect on smooth muscle. As well, alcohol taken in large quantities or chronically over time can cause sedation and decreased libido.…”