Erectile Dysfunction

Educational Objectives

The goal of this program is to improve management of erectile dysfunction (ED). After hearing and assimilating this program, the clinician will be better able to:

1. Compare early interventions for ED to newer therapies.
2. Identify and treat men with Peyronie disease.

Summary

Penile anatomy and erectile function: 3 cylinders (corpora cavernosa, urethra) within cylindrical organ; corpora cavernosa — contains arteries; with stimulation, blood flow increases and fills sinusoids; penis distends and elongates; tunica albuginea — soft, pliable envelope of corpora cavernosa; becomes rigid with distension of penis; pathway — stimulation leads to release of nitric oxide and activation of guanylate cyclase; concentration of cyclic guanosine monophosphate increases, causing smooth muscle to relax; blood flow increases

Erectile dysfunction (ED) therapy: vacuum devices — vacuum draws blood into corporal bodies of penis; once corporal bodies engorged, constriction band placed around base to hold blood in place, in order to maintain erection; inexpensive (eg, $100); safe; patients complain about decreased sensation and lack of erection proximal to band

Injection therapy: papaverine — introduced during 1980s; intracavernosal injection; prostaglandin E1 (PGE1) — introduced in 1983; inhibits release of norepinephrine; metabolized in local tissues and in lungs (half-life short); risk for priapism low; trimix — introduced in 1990; combination of PGE1 (stimulates adenylate cyclase), papaverine (inhibits phosphodiesterase type 5 [PDE5]), and phentolamine (increases production of nitric oxide); using lower dose of each medication in combination may result in additive effect (lowers risk for priapism); efficacy rate 80% to 90%; 30% to 62% of men who did not respond to single agent or oral medication developed rigid erection with trimix; injected into corporal body; adverse effects include priapism, fibrosis, and pain; drop-out rate >50% at 2 yr

Intraurethral PGE1 (alprostadil [eg, Muse]) suppository: not as effective as PGE1 injection; requires refrigeration; patient uses applicator to place pellet in urethra

Sildenafil (Viagra): first effective, oral medication for ED; in 1991, researchers investigating compound UK92480 for treatment of angina and hypertension discovered that compound inhibited PDE5; in March 1998, sildenafil approved by U.S. Food and Drug Administration (FDA) for use in men with ED and for treatment of pulmonary hypertension

Peyronie disease: caused by development of scar tissue in tunica albuginea; may lead to deformity and pain; typically not severe, but may lead to loss of ability to have sexual intercourse

Treatment: collagenase injection — eg, Xiaflex; breaks down collagen; multiple injections required; surgery — plication, grafting, use of inflatable or malleable prosthesis (often requires revision within 5 yr)

Platelet-rich plasma injection: eg, Priapus Shot, P-shot; injection of platelet-rich plasma into penis and corporal bodies; 5 injections per treatment; patients offered boost at 3 mo; not approved by FDA; costs ≈$1900; proposed mechanism of action — platelets release growth factors and stimulate repair of tissue; claims — immediately enlarges penis; strengthens and straightens penis; increases circulation within penis; effects last ≈1 yr; in clinic, platelet-rich plasma injections provided with trimix injection; studies — no direct evidence that platelet-rich plasma injections improve erectile function or increase girth or length; most studies performed with pudendal nerve crush; some improvement seen in animal models

Stem cell injections: fat-derived or hematopoietic stem cells from patient injected into penis; proposed mechanism of action — anti-inflammatory effects; stem cells migrate to damaged tissue and recruit repair cells; encourages remodeling of scar tissue; inhibits apoptosis; some stem cells may differentiate into normal cells when bound to substrate in injured tissue; studies — included rats with injury to cavernous nerve; stem cells injected into pelvic ganglia or corpora; increased pressure upon stimulation of penile nerve; although results suggest potential for repair in animal models, findings not reproduced in humans; ingrowth of nerve tissue in corporal tissue increases after injection

Low-intensity extracorporeal shockwave therapy (LiSWT): corporal bodies subjected to multiple shockwaves; no anesthesia or down time required; proposed mechanism — shockwave creates shear stress in vascular tissue, which induces proliferation of blood vessels and neovascularization; studies — number of shocks and intensity of shocks used vary; greater number of shocks (eg, 18,000) associated with better outcomes; effects may last >3 mo; shown to improve overall function and erection hardness; 50% of men who initially did not respond to PDE5 inhibitors were able to achieve erections with PDE5 inhibitors after treatment with LiSWT; more effective in men with mild ED; not as effective in patients with diabetes; Sexual Medicine Society of North America, Inc. states insufficient evidence to recommend use; concerns — risk for fibrosis and curvature

Costs: platelet-rich plasma injection — $1800 (includes 20 doses of trimix); stem cell therapy — $8000 to $15,000; LiSWT — $3000 to $6000

Questions and answers: treatment options for ED patients receiving medical castration for prostate cancer — vacuum erection device; injection therapy; surgery; ability to achieve nocturnal erections but not volitional erections — some men able to achieve reasonable response in relaxed state, but unable to have erection during sexual activity because of, eg, anxiety; trials of PDE5 inhibitors — PDE5 inhibitors expensive; failure to respond to 1 agent “not a great sign”; generic sildenafil available; if patient does not respond to 3 trials, then consider other options; testosterone — does not cause prostate cancer; low testosterone may diminish sexual performance; testosterone replacement part of overall ED management, but rarely stand-alone treatment for ED

 

Readings

Bechara A et al: Twelve-Month Efficacy and Safety of Low-Intensity Shockwave Therapy for Erectile Dysfunction in Patients Who Do Not Respond to Phosphodiesterase Type 5 Inhibitors. Sex Med. 2016 Dec;4(4):e225-e232; Garrido Abad P et al: Safety and efficacy of intraurethral alprostadil in patients with erectile dysfunction refractory to treatment using phosphodiesterase-5 inhibitors. Actas Urol Esp. 2015 Dec;39(10):635-40; Lin H et al: Nanoparticle Improved Stem Cell Therapy for Erectile Dysfunction in a Rat Model of Cavernous Nerve Injury. J Urol. 2016 Mar;195(3):788-95; Wu YN et al: Optimization of platelet-rich plasma and its effects on the recovery of erectile function after bilateral cavernous nerve injury in a rat model. J Tissue Eng Regen Med. 2016 Oct;10(10):E294-E304; Yafi FA et al: Therapeutic advances in the treatment of Peyronie’s disease. Andrology. 2015 Jul;3(4):650-60.

Disclosures

For this program, members of the faculty and planning committee reported nothing to disclose. In his lecture, Dr. Rames presents information related to the off-label or investigational use of a therapy, product, or device.

Acknowledgements

Dr. Rames spoke at Family Medicine Update 2018, presented June 11-16, 2018, in Kiawah Island, SC, by the Medical University of South Carolina, Department of Family Medicine. Please visit http:// www.musc.edu/cme for information about upcoming conferences from this sponsor. The Audio Digest Foundation thanks the speakers and sponsors for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.

Lecture ID:

FP664101

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.

More Details - Certification & Accreditation