TriMix is a common term used to describe a mixture of Papaverine, Phentolamine and Alprostadil (PGE). Each of these drugs produce a vasodilating effect when injected into the penis. The injection is done using a very small needle, inserted into the proper area along the shaft of the penis, so the drug mixture is delivered into the corpus cavernosum. The mixture of drugs causes the corpus cavernosum to relax, dilate and become filled with blood, producing an erection. Trimix injections can provide almost instantaneous results, with erections typically appearing within 5 to 20 minutes after the injection.