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What is the role of Ach in an erection?
- 1. Ach stimulates:
- Increased production of NO
- Increased cGMP conversion by guanylate cyclase
- Decreased intracellular Ca in penile Artery smooth muscle cells
- Increased blood flow
- Erection
- 2. Ach stimulates:
- Increased activity of adenyl cyclase
- Increased cAMP
- Decreased intracellular Ca in penile artery smooth muscle cells
- Increased blood flow
- Erection
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What is the normal physiology of an erection?
- With stimulation, smooth-muscle cells relax, which allows the sinusoids to engorge with blood and causes the penis to become tumescent
- As the sinusoids expand, they compress the subtunical venous plexus, which causes an erection
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What is the pathophysiology of ED?
- Insufficient relaxation of smooth-muscle cells
- Decreased sinusoid compliance
- An inadequate number of smooth-muscle cells
- Tunical degeneration (Peyronie's disease)
- Insufficient compression of the subtunical veins results in erectile dysfunction
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What are the common mediations to cause ED?
- Thiazindes
- Spironolactone
- BBL
- Methyldopa
- Clonidine
- Digoxin
- SSRIs
- TCAs
- Alcohol
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What is the MOA of PDE-5 inhibitors in ED?
Increase penile cGMP, resulting in relaxation of smooth-muscle cells allowing more blood in to the corpora
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What is the method of action of Alprostadil in ED?
Increases the concentration of cAMP and decreases the intracellular Ca concentration resulting in relaxation of smooth-muscle cells
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What's the place in therapy for vacuum constriction devices in ED?
- For pts who do not respond to oral or injectable drug treatments
- Older pts who are married or have stable sexual relationships
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What's the place in therapy for penile prosthesis implantation?
For pts who do not respond to or are not candidates for oral or injectable tx
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What is the MOA of testosterone replacement regimens in ED?
- Restore serum testosterone levels to correct sx of hypogonadism
- Stimulate androgen receptors in the CNS to maintain normal sexual drive
- Stimulate NO synthaseto increase NO concentrations and the effects of PDE-5 in cavernosal tissue
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What are the SE of PDE-5 Inhibitors?
- Visual blue-green haze (not tadalafil)
- Flushing
- Nasal congestion
- HA
- Dyspepsia
- decreased BP
- Priapism
- Increased risk of MI
-
What drugs are CI with PDE-5 Inhibitors?
- Nitrates
- fatty meals (not tadalafil)
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What are the SE of Alprostadil?
- Hypotension
- Penile ache
- Leg ache
- Burning sensation in the urethra
- Penile fibrosis
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What are the counseling points that should be covered with PDE-5 Inhibitors?
- No effect on erection w/o stimulation
- Take Sildenafil on an empty stomach 2hrs before meals
- Increased success rates with sequential doses
- Take Sildenavil and Vardenafil 30-60 min before sex
- Take Tadalafil 2 hrs before sex
- Avoid nitrates
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What erectile dysfunction etiologies compose organic erectile dysfunction?
- Vascular (PVD, arteriosclerosis, HTN)
- Neurologic (Spinal cord injury, Stroke, DM)
- Hormonal (aging, hypothalamia)
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Why is testosterone not given orally?
- bioavailability poor
- hepatotoxic
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