Intracavernous injection of prostaglandin E1 in combination with papaverine: enhanced effectiveness in comparison with papaverine plus phentolamine and prostaglandin E1 alone.

We compared the erectile response to intracavernous injection of a combination of papaverine and prostaglandin E1 with that of a combination of papaverine and phentolamine (49 patients), and prostaglandin E1 alone (38). The degree of erection achieved was significantly better with papaverine plus prostaglandin E1 than with papaverine plus phentolamine and the duration of erection was less, although the incidence of prolonged erections (greater than 5 hours) was similar with both combinations. Papaverine with prostaglandin E1 likewise resulted in a significantly better degree of erection than prostaglandin E1 alone (prolonged erections occurred only after the drug combination). All erections subsided spontaneously and none required medical intervention throughout the study. Pain was noted only after injection of prostaglandin E1. The incidence was clearly lower (7 of 38 versus 13 of 38) after the injection of only 5 micrograms. prostaglandin E1 in combination with papaverine (although the difference is not statistically significant). Subjectively, the side effects caused by the drug combination were described as much less dramatic by the patients than after prostaglandin E1 alone. The combination of papaverine and prostaglandin E1 shows a clearly synergistic effect and might suitably replace papaverine plus phentolamine or prostaglandin E1 alone in patients who do not respond well or suffer side effects after high single doses.