Erectile dysfunction is the inability to attain and maintain an erection enough to have satisfactory sexual performance for ≥3 months.

It is when the patient complains of partial erection that could not attain vaginal penetration.

Complete loss of penile rigidity is uncommon.

Initial penile erections can penetrate but early detumescence occurs without ejaculation.

Principles of Therapy

Goals of Therapy

  • Identify & treat any curable causes of erectile dysfunction
  • Initiate lifestyle & risk factor modifications
  • Provide education & counselling to patients & their partners
  • Correct any existing medical risk factors:
    • Regulate glucose in poorly controlled DM
    • Optimize antihypertensive medications
    • Treat hyperlipidemia aggressively
    • Reduce/stop alcohol intake

Erectile Dysfunction Caused by Hypogonadism/Testosterone Deficiency

  • Not all hypogonadal males have erectile dysfunction
  • Patient usually has slow but steady increase in erectile dysfunction & progressive loss of libido over a few mth
    • Patients who have a temporary decrease in hypothalamic-pituitary-gonadal axis functioning (eg after surgery or acute medical events, anxiety or alcohol) are unlikely to respond to androgen replacement
  • Initiate androgen replacement
    • If prostate is normal [normal prostate-specific antigen (PSA), no benign prostatic hyperplasia (BPH)]
    • Reassess patient w/in 1-3 mth then every 6-12 mth
  • If no improvement in sexual function after 3 mth
    • Hormone deficiency may not be the only cause for sexual dysfunction
    • Patient may wish to try other treatment options


Nonspecific Therapy for Erectile Dysfunction

Phosphodiesterase-5 Inhibitors (PO)

  • Eg Avanafil, Sildenafil, Tadalafil, Udenafil, Vardenafil
  • If there is no contraindication, oral phosphodiesterase-5 (PDE5) inhibitors should be offered as a 1st-line therapy
    • Highly effective, noninvasive
  • Have proven efficacy & safety in both non-selected populations of men w/ erectile dysfunction & in specific subgroups of patients (eg men w/ DM & those who have had a prostatectomy)
  • Contraindicated in patients taking nitrates
  • Sexual stimulation is still required
  • Works peripherally; inhibits phosphodiesterase type 5, which is found in the penile tissue
    • Increases smooth muscle relaxation in the corpora cavernosa & enhances penile rigidity
  • It is currently recommended that patients receive 8 doses of a PDE5 inhibitor w/ sexual stimulation at a maximum dose before classifying a patient as a non-responder
  • Patients need to be counseled on side effects & interactions

Alprostadil (topical)

  • Phase II clinical trials showed topical Alprostadil to be effective in patients w/ mild to severe erectile dysfunction symptoms
  • Topical administration eliminates the need of intraurethral or intracavernosal inj of Alprostadil
  • Seems to be safe in patients who are otherwise healthy, those undergoing treatment for CV disease & DM patients

Apomorphine (sublingual)

  • No drug interaction w/ nitrates
    • May be an option for men who cannot take phosphodiesterase inhibitors due to nitrate use (however, manufacturers still advise to be cautious when used w/ nitrate)
  • Sexual stimulation is still required
  • Works at the CNS; agonist of the D1 & D2 postsynaptic receptors for dopamine
  • Erectogenic effects are usually seen w/in 20 min of sublingual administration
    • Best efficacy was reported in patients w/ mild-moderate erectile dysfunction & may perhaps be better for men who
      have some residual erectile function & in younger patients

Yohimbine (PO)

  • Alpha2-adrenergic antagonist
  • Has been shown to be more effective in psychologic erectile dysfunction than organic erectile dysfunction
    • Has been combined w/ Trazodone to increase responsiveness
Intracavernosal Inj Therapy
  • Drugs administered via this route are Alprostadil, Papaverine & Phentolamine
  • Indicated in patients not responding to oral drugs
  • Most effective nonsurgical treatment for erectile dysfunction but has highest risk for priapism
  • Invasive therapy & therefore proper training of patient in intracavernosal inj is necessary
  • Initial trial dose must be given under the supervision of physician
  • Should be used only once w/in a 24-hr period
  • Inform patient of the potential event of prolonged erection
  • Physician must be prepared for urgent treatment of possible prolonged erections & inform patient of this treatment plan beforehand
  • Direct action on the corporal smooth muscle
  • Rapid onset of action, highly effective

Intraurethral Therapy

  • Drug administered via this route is Alprostadil
  • Alternative to intracavernosal inj therapy
    • Less invasive
  • Transfer of drug from urethra directly to the corpora cavernosa
  • Consider in patients who have unsatisfactory results w/ oral phosphodiesterase inhibitors or are not candidates for the said drug
  • Initial trial dose must be given under the supervision of physician because of the risk of syncope
  • The combination of Alprostadil suppositories w/ either a penile constriction device or oral phosphodiesterase inhibitors has been shown by some studies to be more efficacious over Alprostadil alone
  • Intraurethral Alprostadil has been shown to be effective in 60-70% of patients

Non-Pharmacological Therapy

Vacuum Constriction Device

  • Negative pressure is applied to the pendulous penis causing blood to be drawn into the penis
  • Blood is retained in penis by elastic band placed at the base
  • Highly effective in inducing erections regardless of erectile dysfunction etiology
  • Only devices w/ a vacuum limiter should be used
  • Preferred by patients who do not want to use pharmacological therapy or in whom medication is contraindicated
  • Contraindicated in patients w/ bleeding disorders or on anticoagulant therapy
  • Low-cost & effective; reported satisfaction rates vary from 35-84%
  • May be used on an “on demand” basis
  • May be seen as cumbersome
  • Side effects include penile pain, numbness, petechiae, bruising & slowed ejaculation
    • Serious adverse events are very rare but skin necrosis has been reported
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