Papaverine was one of the first injectable medications used to treat erectile dysfunction. It is a vasodilator, which means that it expands blood vessels and increases blood flow into the penis. When papaverine is injected into the intracavernosal space in the penis, it increases blood flow, resulting in an erection. Papaverine is no longer used alone to treat ED. It is used in combination with Phentolamine and Prostaglandin to give better treatment results with fewer side effects. Papaverine is one of four medications that compose a class of injectable erectile dysfunction medications often called Bimix, Trimix, or Quadmix. Most patients who suffer from erectile dysfunction buy Papaverine as part of the Trimix compound.