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Medical management of ED

Principles of management:

  • Patient (and partner) education and expectations are key.
  • Identification of modifiable risks / treatable conditions, and potentially concomitant conditions (sort out the heart first)
  • Shared decision making approach – patient to weigh up pros and cons of treatment options
  • Incorporating psychological and couples counselling when appropriate

Lifestyle modification

  • Good evidence for efficacy of:

Medical adjuncts / reversible causes

  • Optimise diabetic control
  • Treat identified endocrinopathy (hypogonadism, hyperprolactinaemia)
  • Stop or replace potential contributing medications
  • Psychological counselling
  • Patient education

 

PDE5 inhibitors

  • The key step is achieving erections is smooth muscle relaxation mediated by NO release from cavernosal nerves. NO stimulates cGMP which facilitates smooth muscle relaxation.
  • cGMP is degraded by the enzyme phosphodiesterase 5. Therefore, PDE5 inhibitors prevent the breakdown of cGMP.
  • PDE5 inhibitors augment but do not induce erections – i.e. use of PDE5i must be coupled with sexual stimulation.
  • Typical success rates 60 – 75 %. Clearly established efficacy cf. placebo, with all options roughly equal in terms of efficacy.
  • May be less efficacious in men with damage to cavernosal nerves (radical prostatectomy, diabetic neuropathy) as the nerves are still required to release NO and cGMP.
  • Different medications have slightly different profiles in terms of efficacy and side effects. Some patients may have adverse effects with one and not another, or find the efficacy better with one type.

 

Contra-indications for PDE5i:

  • Concurrent nitrate use (GTN, isosorbide mononitrate (Duride, Imdur, Isobide, Monodur)
    • Unpredictable severe hypotensive episodes
  • Amyl nitrate use (poppers)
  • Use in caution with anti-hypertensives – but blood pressure drops are usually transient and minor
  • Use in caution with alpha-blockers – potential blood pressure drop – EAU guidelines state OK to use both as may drop blood pressure but no proven increase in adverse events
  • Metabolised by CYP3A4 system – possible drug interactions
  • Vardenafil not recommended in men taking anti-arrhythmic medication
  • Contraindicated in use with riociguat (Adempas – cGMP inhibitor) used in severe pulmonary hypertension and nicorandil (Ikorel)
  • Historical concern re: nonarteritic anterior optic neuropathy (NAION) – has not been borne out in studies

 

Side effects of PDE5i:

  • Headache 10 – 20 %
  • Flushing
  • Indigestion / dyspepsia
  • Nasal congestion
  • Visual changes around 2 % including blue vision with sildenafil
  • Back pain and myalgia (6 % with tadalafil)

 

 

Optimal use:

  • Must have sexual stimulation concurrently to allow NO release
  • Must wait a period of time after taking medication
  • Ensure taking a pharmacy supplied medication (cf. online/counterfeits)
  • Increase dose if low-starting dose not effective
  • Try at least half a dozen separate times before calling it a failure
  • Avoid concurrent food especially fatty food
  • Correct other lifestyle risk factors and address psychogenic factors
  • Try a different medication

 

Regular use of PDE5 inhibitors:

  • Area of ongoing research
  • Mainly studied in post radical prostatectomy setting
  • No good evidence that ability to achieve spontaneous erections is regained after cessation of PDE5i
Vacuum erection devices (VED)
  • Passive engorgement of the corpora combined with a constricting ring at the base to retain blood flow
  • Published efficacy > 90 % for erection for intercourse, but high discontinuity rates in both short and long term
  • May cause pain, skin changes, ejaculatory dysfunction, bruising and numbness
  • Contra-indicated in anti-coagulated patients
  • Glans enlarges too (cf. implants)
  • Recommend ring comes off after 30 minutes
Intra-urethral and topical alprostadil
  • Topical cream (Vitaros) and intra-urethral pellet (MUSE).
  • MUSE dose 500 – 1000 ug.
  • Efficacy 30 – 65 %.
  • Side effects include pain (30 – 40 %), possibly hypotension, urethral bleeding and UTI.
  • Less efficacious than intra-cavernosal therapy, but some patients may find more tolerable.
  • Can get glans engorgement for those with implants and floppy glans
  • 5 % risk of female partner burning/itching, condom recommended for pregnant partners.

 

Shockwave therapy
  • Emerging treatment with promising results in single-arm trials but conflicting results in prospective randomised trials.
  • Significant heterogeneity in shockwave generators, types of shockwaves (focused/linear/unfocused) and treatment protocols.
  • Studies tend to show modest improvement in IIEF and erectile hardness score in patients with mild vasculogenic ED – 40 – 80 % satisfactory improvement.
  • Weak recommendation in EAU guidelines for patient with mild vasculogenic ED or vasculogenic ED with poor response to PDE5i.

 

Intracavernosal injections

  • Injection of vasoactive agent directly into one corpora cavernosum. Injection point is generally laterally to avoid dorsal neurovascular structures and urethra.
  • Uses small 29 or 31 gauge needle to minimise discomfort. Massage the agent in after injection.
  • Can be offered as single agent monotherapy or combination therapy. 60 – 80 % success.
  • Site of injection should be alternated.
  • Start at a low dose, supervised by experienced professional providing education. Erection should occur 15 – 30 minutes after injection. Failure at home after successful trial in rooms suggests failure in delivery or preparation.

Side effects:

  • Priapism is most concerning – education necessary, consider pseudoephedrine as needed, clear instructions on when to present
  • Pain most common side effect (esp with alprostadil) – up to 30 %
  • Bruising and scarring
  • Failure
  • Occasionally flushing

 

Relative contra-indications:

  • Blood disorders (sickle cell, leukaemia etc) may predispose to priapism
  • Anticoagulation is OK but higher risk of bruising, need good compression
  • Poor manual dexterity
  • Blindness
  • Previous priapism
  • MAO inhibitor use (alpha agonists used to treat potential priapism would induce hypertensive crisis)

Single agent – caverject (alprostadil). Dose can be titrated each use in custom designed injector syringe.

Trimix – combination alprostadil, papaverine, phentolamine. May be more efficacious. More cost effective as a vial kept in the fridge provides multiple doses.

Bimix – papaverine and phentolamine – avoids pain from alprostadil.

Invicorp – combination VIP and phentolamine