Click here to view next page of this article

Erectile Dysfunction

Definition of Erectile Dysfunction (ED)

Prevalence of ED

Approximately 5% of men at age 40, increasing to 15% - 25% by age 65

Prevalence increases with age, but ED is not an inevitable and untreatable consequence of aging

Causes of ED

• Vascular disease

• Neuropathy

• Latrogenic factors

• Congenital abnormalities

• Peyronie's disease

• Psychological processes

• Drugs

Diagnosis of ED: History

Detailed sexual and medical history, including:

Nature and frequency of ED

Risk factors for ED, eg:

Concurrent disease

Drug abuse

Psychiatric illness

Risk Factors for ED

• Hypertension

• Hyperlipidemia

• Hypogonadism

• Endocrine disorders

• Smoking

• Alcohol abuse

• Trauma or surgery to the pelvis or spine

• Depression

• Drug abuse

• Anemia

• Vascular disease

• Peyronie's disease

• Vascular surgery

Drugs Associated with ED

• Alcohol

• Estrogens

• Antiandrogens

• H₂ receptor blockers

• Anticholinergics

• Ketoconazole

• Antidepressants

• Marijuana

• Antihypertensives

• Narcotics

• ß-blockers

• Psychotropics

• Cigarettes

• Cocaine

• Spironolactone

• Lipid-lowering agents

• NSAIDs

• Cytotoxic drugs

• Diuretics

Diagnosis of ED: Physical Examination

• Assessment of secondary male sexual characteristics

• Femoral and lower extremity pulses

• Focused neurologicexamination

• Perianal sensation

• Sphincter tone

• Bulbocavernosus reflex

• Examination of penile vasculature

• Evaluation of prostate size by digital rectal exam

• Detection of Peyronie's plaques

Laboratory Tests

• Morning serum testosterone specimen

• Serum prolactin

• Tests for other systemic disease

Complete blood count

Special Tests: Indications

• Vasoactive agent injection

Intracavernosal injection therapy

Penile prosthesis implantation

Vascular surgery

• Nocturnal penile tumescence, eg, Snap-Gauge, Rigiscan

Screen for psychogenic vs organic ED

• Duplex ultrasonography

Vascular surgery

Treatment Options for ED

• Psychosexual counseling

• Hormonal replacement

• Vacuum pumps and constriction devices

• Penile implants

• Vascular surgery

• Injectable medications

• Oral medications

Hormonal Therapy

• Androgenic steroids
• May be effective in a small fraction of ED patients with documented hypogonadism
• Oral, parenteral, transdermal preparations available
• Exogenous testosterone caveats
• Can suppress remaining endogenous androgen production
• May be metabolized to estradiol with potentially detrimental effects on sexual function
• May increase risk of prostate hypertrophy and cancer (check PSA before starting therapy!)

Vacuum Constriction Devices

• Most common device used for ED

No tests required beyond initial evaluation

Transurethral Alprostadil (MUSE)

• Efficacy

Approximately 2/3 of patients using the active drug had sexual intercourse (compared to 19% with placebo)

The efficacy of transurethral alprostadil did not differ significantly depending on the etiology of the ED

• Safetyand Adverse Events

Penile pain was reported for 10.8% of alprostadil administrations and by 32.7% of men

Only 2.4% of men discontinued because of pain

Vasoactive Intracavernosal Pharmacotherapy

• Intracavernosal injection of vasoactive agent (eg, alprostadil [Caverject and Edex], phentolamine [Invicorp])

Relaxes cavernous and arterial smooth muscle

Oral Pharmacologic Treatments

• Existing oral therapies

Yohimbine

Trazodone

L-arginine

• FDA-approved new agent

Sildenafil (Viagra)

• New agents under investigation

Apomorphine (Spontane)

Phentolamine (Vasomax)

Sildenafil

• Mechanism of Action

Nitric oxide acts through a second messenger, cGMP, in the normal development of erections

cGMP relaxes corpus cavernosal smooth muscle cells, promoting blood flow into cavernosal spaces

cGMP broken down by PDE - the predominant enzyme of this type inthe corpus cavemosum is PDE type V

Sildenafil is a selective and potent inhibitor of PDE type V

• Efficacy

Three UK clinical trials (N=12; N=42; N=351)

Apomorphine

• Mechanism of Action

Central dopamine receptoragonist

Causes a well-recognized erectile response in rats

• Mechanism of Action

a-adrenoceptor antagonist

Inhibits adrenergic-induced contractile tone with resulting relaxation response causing:

Increased blood flow into the sinusoidal spaces of the cavernous

Penile Implants

• Two types: semirigid and multicomponent inflatable

• Patient satisfaction rates range from 81% to 97%

• Average functional life of prostheses is 7 to 10 years

Vascular Surgery

• Best for young men with vascular arterial trauma
• May be used to correct demonstrated venous leakage