Papaverine
Sexual Well-Being
In plain English
Papaverine is a muscle-relaxing medicine used as part of penile injection therapy (Tri-Mix) to produce an erection. It relaxes the blood vessels in the penis so blood can flow in. It is injected into the penis before sexual activity for men who need more than oral pills. A key risk is a prolonged erection (priapism).
The science
Papaverine is a non-specific phosphodiesterase inhibitor and smooth-muscle relaxant (raising cavernosal cAMP/cGMP) that produces vasodilation independent of nitric oxide, making it effective even in neurogenic and some vasculogenic erectile dysfunction. It is a core component of intracavernosal Tri-Mix; a randomized study (Seyam 2005) showed Tri-Mix combinations achieve hemodynamic effects and satisfaction comparable to prostaglandin E1, with a longer erection duration and higher priapism rate. Risks specific to papaverine/intracavernosal therapy include priapism, corporal fibrosis with repeated use, and (historically with papaverine) transaminase elevation. There is no FDA-approved papaverine product for erectile dysfunction; intracavernosal use and compounded Tri-Mix are off-label. Men must be counseled on priapism rescue.