Here are the common agents and combination of agents used for penile injection to induce an erection.
1. Papaverine is available at a low cost and is stable at room temperature but is less effective than the other medications and may have a higher tendency to cause scarring (fibrosis).
2. Papaverine plus phentolamine (BiMix) is more potent than papaverine alone but with the same potential side effects such as priapism and scar tissue formation. It requires refrigeration
3. Alprostadil rarely causes priapism but with its use pain is more common. (Alprostadil is also known as prostaglandin E-1 or PGE-1, in powdered form it may be called Caverject or Edex.)
4. Papaverine plus phentolamine plus Alprostadil (Trimix) is the most potent but requires refrigeration and has the same side effects as Papaverine and Alprostadil.