trimix (drug) trimix (drug) trimix is a prescription combination drug containing alprostadil, papaverine, and phentolamine. it is used to treat erectile dysfunction. trimixcombination ofalprostadilprostaglandinpapaverinevasodilatorphentolaminealpha blockerclinical dataroutes ofadministrationinjection, intraurethral, topicallegal statuslegal status us: ℞-only identifierschemspidernone (verify) medical use available forms trimix is available in several different formulations, including a gel that can be used topically, a gel that can be administered into the urethra, and an injectable form that is administered via intracavernosal injection (an injection at either side, not the base, of the penis). adverse effects adverse effects from injecting trimix may include pain, fibrosis, hematoma, and priapism (a prolonged erection of the penis). pharmacology trimix is a combination of three drugs: alprostadil, papaverine, and phentolamine. these medications work in combination to increase blood flow to the penis, resulting in an erection. alprostadil is a prostaglandin vasodilator that allows more blood to flow into the area by relaxing the smooth muscle in the blood vessels of the penis. papaverine is a smooth muscle relaxant that acts by increasing blood flow to the penis. phentolamine is an alpha blocker that relaxes blood vessel muscles, allowing more blood to flow to the penis. society and culture availability while the active drugs in trimix have all been individually approved by the u.s. food and drug administration (fda), trimix as a combination drug has not been approved by the fda and is only available from compounding pharmacies. trimix is typically prepared by the compounding pharmacy in a sterile environment and then frozen. the compound is stable for up to six months while stored frozen and for one month if stored refrigerated beginning at the time of manufacture.