Erectile dysfunction

ED present in 50% of men > 40 yo

Erection physiology

  • Cavernosal artery smooth muscle relaxation + increased venous outflow resistance = pressure required to maintain erection
    • Parasympathetics → NO release → cGMP, decreased Ca → smooth muscle relaxation
    • Cavernosa expand and compress venous outflow
  • Sympathetic → NE → α adrenergic → detumescence

History:

  • Presentation
    • Onset/duration of ED, last successful intercourse, frequency of intercourse now vs 1 yr ago
    • Maximum rigidity, able to sustain/penetrate
    • Presence of nocturnal/morning erections, erection w/ masturbation
    • Libido, ejaculatory dysfunction, orgasmic dysfunction, sexual satisfaction
    • Penile curvature
    • Relationship problems, performance anxiety, stress
  • Culprit medications
    • βblockers, thiazides, clonidine, methyldopa
    • antidepressants/antipsychotics
    • anti-testosterone (cimetidine, spironolactone)
    • sedatives, anticholinergics, alcohol/tobacco
  • Culprit diseases
    • CKD, DM, liver disease, EtOH, neuro, thyroid, atherosclerosis, post-surgery/trauma

Exam:

  • Cardiovascular exam
  • Genital exam, secondary sexual characteristics
  • May assess erectile dysfunction with intracavernosal injection (good erection rules out veno-oclusive disease)
  • Look out for penile plaques or endocrine/pituitary abnormalities (gynecomastia, visual field defects)

Testosterone levels

**hide**Optional/if clinical suspicion: prolactin

General recommendations - optimize cardiovascular health.

Step-wise approach to therapies: be as aggressive as the patient wants to be. 

Contraindications: predisposition to priapism, significant penile angulation/fibrosis, 

  Mechanism of action Use Side effects Contraindications
PDE-5 inhibitors Increase cGMP → smooth muscle relaxation → erection
  • Viagra = sildenafil 25 - 100 mg. Use 1 hr before sex on empty stomach
  • Cialis = tadalafil 10 - 20 mg. More amenable to taking with food; effects last 24 hrs but is less potent
  • Levitra = vardenafil
  • Can use daily low dose (e.g. Cialis 5) or higher on-demand dose (e.g. Cialis 20)
 headache, flushing, blue vision (retina has PDE-6), backache, congestion

DO NOT USE WITH NITRATES (due to increased NO) - causes dangerous hypotension

**hide**Caution also with co-administering a-blocker

Avoid in: hypotension < 90/50, retinal PDE diseases
MUSE (medicated urethral system for erection) Alprostadil (PGE1) stimulates cAMP production → decreased Ca → smooth muscle relaxation
(less effective than injections)		 Intraurethral alprostadil 145-1000 mcg
Erection begins 5-20 min after administration		 Urethral pain/burning urethral stricture, penile/urethral inflammation, unprotected sex with pregnant female
Intracavernosal injections Alprostadil as above
Papaverine inhibits phosphodiesterases
Tri-mix = PGE1 + Papaverine + Phentolamine

Dose titration should be supervised.
Alprostadil - start with in-office injection 20 mcg (40 mcg for Peyronie's assessment). Max dose 60 mcg 3x/week.

Inject 3 and 9 oclock

Tri-mix - start with 0.1 cc, titrate by 0.05. Each vial is 2.5 cc (about $5/injection)

Penile pain/burning (alprostadil > papaverine)

Peyronie's (papaverine > alprostadil)

 Significant penile angulation/fibrosis, penile implant
Vacuum + occlusive ring Vacuum draws blood into penis, and occlusive ring maintains erection Max duration use 20-30 min, with at least 1 hr between each use. Use with a vaccum limiter.
About $250-$300		 Penile buckling, cold/numb penis, hematoma, pain
Penile prosthesis (IPP) Malleable (semi-rigid), 2-piece or 3-piece inflatable implants Malleable is semi-rigid; inflatables are pumped up for use    

ED treatment in renal failure patients

  • ESRD associated with hypogonadism
  • PDE-5i effective but may increase hypotension, limit to use on non-dialysis days
  • Coagulopathy/platelet dysfunction may predispose to bleeding with injections
  • ED can improve after transplant so defer IPP until after transplantation
author: admin | last edited: Oct. 9, 2020, 1:37 p.m. | pk: 1