Erectile Dysfunction

Question 1

Describe erectile dysfunction

Answer 1

Refers to the inability of a man to achieve or maintain an erection

Question 2

Other than hypogonadism, name some of the causes of erectile dysfunction

Answer 2

• psychological (performance anxiety, stress)
• neurogenic (damaged nerves, alcoholism)
• Vascular issues (causing damaged or blocked blood vessels)
• drug induced (drug abuse, beta blockers, etc)

Question 3

During an erection, which anatomical structure fills with blood?

Answer 3

Corpus cavernosum

Question 4

What happens to the blood vessels during an erection?

Answer 4

The artery widens to allow for more blood flow, whereas the veins are compressed which prevents the blood from leaving.

Question 5

Which parasympathetic nerves extend from the spinal cord to supply the penis?

Answer 5

NANC - NorAdrenergic and NonCholinergic nerves

Question 6

During the flaccid state, which nervous system is responsible for keeping the smooth muscle and blood vessels constricted?

Answer 6

The sympathetic nervous system

Question 7

Activation of the NANC nerves stimulates the production of …?

Answer 7

Nitric oxide

Question 8

How does nitric oxide cause an erection?

Answer 8

Nitric oxide produced in the NANC nerves gets released when there is cholinergic activation. Nitric oxide then initiates a cascade of events that leads to a decrease in intracellular calcium, leading to smooth muscle relaxation

Question 9

What causes an erection, smooth muscle relaxation or contraction? Why?

Answer 9

Relaxation. This allows for blood flow into the corpus cavernosum, which clamps down on the exiting veins.

Question 10

Explain the prostaglandin pathway of an erection

Answer 10

PG-E1binds to a smooth muscle receptor, which converts ATP into cAMP, which then activates protein kinase A. This causes the phosphorylation of certain proteins which opens the potassium channel, leading to a reduction in intracellular calcium, and therefore, muscle relaxation

Question 11

Explain the effect of adrenaline and the SNS on erections

Answer 11

Noradrenaline release causes muscle contractions, which inhibits erections.

Question 12

Explain the MOA of the alprostadil injection

Answer 12

It is the most common and effective drug treatment.

Works by increasing PG-E1. Needs to be injected into the corpus cavernosum

Question 13

How do the papaverine and phentoalmine injections work?

Answer 13

They both cause vasodilation

Question 14

Explain the benefits of a tri-mix or di-mix injection

Answer 14

The combination of different medications increases the efficacy by approaching the problem from a few different MOAs.
Combines increase in PGs with vasodilation effects.

Question 15

Viagra generic name?

Answer 15

Sildenafil

Question 16

Name 2 other drugs similar to sildenafil

Answer 16

Vardenafil and tadalafil

Question 17

Sildenafil is a phosphodiesterase inhibitor. Explain the MOA

Answer 17

They inhibit the enzymes that break down prostaglandins, which prolongs muscle relaxation and vasodilation.

Question 18

Limitation to sildenafil action?

Answer 18

Still need NANC nerve stimulation, which means you need sufficient nitric oxide levels.

Question 19

How can surgical removal of the prostate affect erections?

Answer 19

The surgery process can cause damage to the penile nerves

Question 20

Name 3 medical conditions that can inhibit ED drugs from working and why

Answer 20

1. Diabetes. Due to decreased NO signalling and increased contractile sensitivity
2. Vascular issues. Prevents sufficient vasodilation
3. Hypogonadal patients. Reduced testosterone levels results in less NO and PGE5

Question 21

How does life-long smoking increase the prevalence of ED

Answer 21

Smoking reduces penile blood flow by hardening blood vessels and increasing sympathetic nervous system tone

Question 22

Nitric oxide and relevant prostaglandins are regulated by which hormone?

Answer 22

Testosterone