Hi Dry Guy,
I have previously tried 5mcg., 10mcg, 20 mcg. of Alprostadil ("Caverject" or "Viridal Duo") and am now taking 40mcg (which I believe is the highest dose available). Strangely, the highest dose does not cause me any more discomfort than the 5mcg. dose. Weird.
I find the 40mcg. dose gives me a strong erection for about 45 minutes. I can still use it for about another 45 minutes, but it's not as hard. After the full hour and a half, my penis is no longer useable for penetration.
Incidentally, I prefer the "Viridal Duo" formulation just because I find it easier to administer.
The main problem I have now is that it is often out of stock 😞.
Best wishes,
JedSee.