Erectile Dysfunction Flashcards
What is erectile dysfunction?
The persistent/recurrent inability to acheive or maintain an erection of sufficient rigidity to permit satisfactory sexual activity for at least 3 months
How is sexual dysfunction different from erectile dysfunction?
More encompassing (can include ED +/- diminished libido, prematue or delayed ejaculation, orgasm, or priapism)
What is the biochemical process by which an erection occurs?
When stimulated, acetylcholine produces an erection via multiple pathways that increase cGMP, cAMP, and NO
This results in smooth muscle relaxation and allows for arterial blood flow to the penis to increase. This results in the corpora to fill with blood
How does erectile dysfunction occur?
Any abnormaility in thr vascular, hormonal, neurologic, or psychogenic system
80% of ED cases are related to organic disease (vascular, hormonal, or neurologic causes)
10% are due to psychogenic factors
up to 25% of ED cases are medication-induced (ex. SSRIs)
What are some risk factors associated with developing ED?
- Age
- Lifestyle (Tobacco, Obesity, Sedentary)
- Medical conditions (CV disease or diabetes)
- Medications
What are some vascular causes of ED?
The most common cause and these disease states compromise vascular flow to the corpora cavernosum
- DM
- Atherosclerosis
- Renal disease
- Liver disease
- Excessive cigarrette smoking
- Radiation
What is the link between ED and coronary artery disease (CAD)?
ED and CAD are both consequences of endothelial dysfunction, leading to restrictions in blood flow
ED in healthy men is associated in development of CAD in the future, therefore monitor for BP, BG, and cholesterol checked
What is the link between ED and diabetes?
Patients with diabetes seem to develop ED at a higher rate and at younger ages likely due to vascular and neurogenic mechanisms altered by diabetes
What are some neurological injuries/conditions that could cause ED?
- Spinal cord trauma
- Stroke
- Pelvic trauma, prostate surgery
- Parkinson’s, Alzheimer’s, MS, epilepsy, diabetic nephropathy, alcoholic neuropathy
What are some hormonal issues that can cause ED?
Primary hypogonadism:
Testosterone naturally declines with age or surgical removal
Secondary hypogonadism:
Can result from hypothalamic or pituitary disorders, hypo/hyperthyroidism, drug-induced cases
What are some common psychogenic causes of ED?
- Stress, performance anxiety
- Fear of STIs or pregnancy, relationship issues
- Depression, other mental disorders (treatment with SSRIs can also contribute to ED)
What are some drug-induced causes of ED?
- Recreational drugs (opioids, alcohol, cigarettes, anabolic steroids)
- Psychotropics (SSRIs, olanzapine, TCAs, risperidone, MAOis)
- CV (thiazides, BBs, CCBs, digoxin, spironolactone)
- 5-alpha reductase inhibitors (finasteride, dutasteride)
- Antiandrogens (leuprolide, ketoconazole, spironolactone)
- Dopamine antagonists (metoclopramide)
- Anticonvulsants (carbamazepine, phenytoin, phenobarbital)
What are the goals of therapy?
- Improve sexual satisfaction
- Improve sexual quality of life
- Improve overall quality of life
What are some non-pharm treatment options for ED?
- Improve diet and exercise
- Smoking cessation
- Limit alcohol/rec drugs
- Psychotherapy
May improve effectiveness of treatment
What is the first-line pharm. option for ED treatment?
PDE-5i (sildenafil, vardenafil, tadalafil)
1st line due to convenience, efficacy, SE profile
What is the MOA of PDE-5i?
Inhibit PDE-5 enzyme which normally degrades cGMP in the corpora cavernosa
Prolonged levels of cGMP enhances NO-induced smooth muscle relaxation and vasodilation in the penis allows for a better erection
When should a patient switch to a different PDE-5i if not seeing benefit?
1st dose can be efficacious, but can see improved success with successive doses
Try a single drug 6-8 times before judging their success
What is the onset and duration of action for the three main PDE-5is?
Sildenafil and Vardenafil (take 30-60 min before intercourse, and last for 4-10h)
Tadalafil (take 2h in advance, but lasts for up to 36h)
What are some drug interactions associated with PDE-5is?
All metabolized by 3A4 (avoid use with ketoconazole, grapefruit juice, erythromycin)
Avoid concomitant use with nitrates (CI)
Non-selective alpha1-blockers (terazosin/doxazasin)
What are some common adverse events associated with PDE-5i?
Overall well-tolerated
Symptoms of vasodilation (headache, flushing, dyspepsia, dizziness, hypotension)
Back and muscle pain
Colour visual changes
What are some serious, but rare ADRs associated with PDE-5i?
Sudden unilateral hearing loss
NAION (unilateral vision loss)
QT prolongation
Priapism (painful erection)
Chest pain
What are some alternate treatment options for ED?
Alprostadil (PGE-1)
Papaverine + Phentolamine
What is the MOA of Alprostadil therapy in ED?
Stimulates increased production of cAMP which causes muscle relaxation of tissues in the corpora and restricts venous outflow (stronger erection)
What is the onset and duration of action for alprostadil therapy in ED?
Inject 10-30 min pre-sex
If erection lasts for more than 1 hour, decrease dose
If erection lasts longer than 4 hours (at risk for damage to penis)
What are some common side effects associated with alprostadil therapy in ED?
Intra-catheteral: penile fibrosis (rotate site and massage site upon injection)
Intraurethral: urethral pain (may cause burning sensation in partner)
Priapism is more common among both alprostadil therapies vs. PDE-5is
Which non-pharmacologic device is used in ED?
Vacuum erection devices
vaccum pulls blood into penis, and a band is placed around the base
What is the utility of Flibanserin in treatment of sexual dysfunction?
Used to treat generalized hypoactive sexual desire disorder
AE: dizziness, nausea, fatigue, hypotension
