phentolamine + papaverine + alprostadil

**Phentolamine + papaverine + alprostadil** (commonly known as Trimix) is a compounded injectable combination drug used as a second-line treatment for erectile dysfunction (ED), particularly in patients unresponsive to oral PDE5 inhibitors like sildenafil. It consists of three synergistic agents: papaverine (a phosphodiesterase inhibitor and smooth muscle relaxer that elevates cAMP/cGMP levels), phentolamine (a nonselective alpha-adrenergic antagonist blocking alpha-1/alpha-2 receptors to prevent vasoconstriction), and alprostadil (prostaglandin E1 analog activating EP2 receptors to increase cAMP and promote vasodilation). Administered via intracavernosal injection, it relaxes penile smooth muscle, enhances arterial inflow, and traps blood in the corpus cavernosum for erection. Developed in the early 1980s, it is produced by compounding pharmacies due to lack of commercial manufacturing, offering rapid onset (5-15 minutes), localized effects, and lower doses to minimize risks like priapism or fibrosis compared to single agents.[1][2][3][4][7]

Brand names

TrimixTri-Mix

Other names

Trimix injectiontri-mixtureTriMix