UNAPROVED AGENTS- PAPVERINE

Question 1

What is the mechanism of action of papaverine?

Answer 1

Papaverine is a nonspecific phosphodiesterase type 5 inhibitor that decreases metabolic catabolism of cAMP in cavernosal tissue, leading to smooth muscle relaxation and penile erection.

Question 2

Why is papaverine not commonly used alone for erectile dysfunction?

Answer 2

Large doses of papaverine alone are required for a therapeutic effect, but they can produce dose-related adverse effects like priapism, corporal fibrosis, hypotension, and hepatotoxicity.

Question 3

What is a common approach for administering papaverine for erectile dysfunction?

Answer 3

Papaverine is more often administered in lower doses in combination with phentolamine and/or alprostadil, which is considered safer and associated with fewer serious adverse effects than high doses of a single agent.

Question 4

What precaution should be taken for patients with liver disease or alcohol abuse when using papaverine?

Answer 4

Patients with a history of underlying liver disease or alcohol abuse should undergo liver function testing at baseline and regularly during continued treatment with papaverine.

Question 5

What are some of the adverse effects associated with large doses of papaverine?

Answer 5

Large doses of papaverine can lead to adverse effects like priapism, corporal fibrosis, hypotension, and hepatotoxicity.

Question 6

What is the usual dose range for papaverine when used in combination for intracavernosal injection?

Answer 6

The usual dose range for papaverine in combination for intracavernosal injection is 0.5 to 20 mg.