I am glad to hear that you are getting good results with intercavernosal injections. I have been using the Caverject (kit) ,it is a single dose of alprostadil (5 mcg to 20 mcg depending upon need). It is also available as a generic Edex (prostaglandin). The single injection has a downside. It usually works very well, but can be accompanied by and aching often painful feeling.
The bi-mix excludes the alprostadil (prostaglandin) and uses papaverine and phentolomine. It works for most users. The tri-mix has all three, with a smaller quantity of the prostaglandin. The Bi-mix is usually best for thoses who have pain problems. However it does not always produce the desired results.
Ok, are you confused now? Go ask your doctor. I am still working my way through this this erection jungle. Best of luck.