David S,
I started using caverject at Day 13 post op to have intercourse. It was
very effective, but hurt like hell. My doc switched me to bimix
(papaverine 30mg  +phentolamine 10 mg) per ml at 0.25 to 0.75 ml per
dose. Over a few months the dose requirement dropped from 0.25 to 0.18.
After about 6 months the pills were working, but I stayed with shots
for most episodes because they worked so well. I tried Caverject again,
and to my surprise it no longer hurt. I don't want to make you feel bad
by telling you how well the shots worked for me. The point is, it is
worthwhile to play with the dose, and to retry things. I think our
response to drugs post RP is very variable and not always constant. You
might try higher dose, or a different mix, or retry caverject/trimix
later. If nothing worked, I'm sure I would go to implant eventually. I
think people sometimes give up too easily. By the way, I developed a
curve at about 15 months. My doc is trying me on colchicine for that. I
would rather wear it out, then lose it to non-use. Sincere best wishes
for success with injections.
Steve U