Regarding alprostadil pharmacotherapy in ED:
A. Prostaglandin E1 cause vasoconstriction of penile veinsAnswer B
Prostaglandin E1 causes direct relaxation of cavernosal smooth muscle and antagonises the action of norepinephrine. These dual effects may explain its efficacy in inducing erections. The Alprostadil Study Group reported a 2% incidence of penile fibrosis. Pain is the major problem associated with alprostadil injection, with an incidence of 16% to 40% and a clear dose dependency. Alprostadil has a higher rate of penile pain compared to papaverine. Prolonged erection occurred in 5% of the men in the Alprostadil Study Group.