But in 1985, it was first reported that a combination of papaverine with phentolamine had an overall effectiveness rate of 72 percent. The drug phentolamine (Regitine) alone has been found to be ineffective in producing an erection. But the drug is so safe and so inexpensive that the company making it never felt it was necessary to pay for a full-scale FDA approval process. And retrospective studies have confirmed its safety for penile injections. Doctors already knew the drug was safe; this was simply a new application. Then, the effects on erectile dysfunction were so profound and became widespread so quickly that the drug was already in common usage for penile injections before an FDA study could have been organized. The drug had been in use already, and had been FDA approved, for other medical procedures involving vascular dilation. But the erection-inducing effects of papaverine were discovered somewhat accidentally. This combination seems to be equally effective with patients over 65, compared with a group of men 20 years younger. Since more studies have been reported, the incidence of priapism has ranged from as low as 1 percent up to 23 percent, while fibrosis has ranged from 2 percent up to 16 percent.

The incidence of prolonged erection, priapism, was less than 2 percent during those early studies, while fibrosis of the erectile cylinders developed in less than 5 percent. In fact, it is so safe that up until Viagra it was probably the most widely used drug in treating erectile dysfunction. This does not mean the drug is not safe. Incidentally, the question may come up that papaverine is not Food and Drug Administration approved for injecting into the penis. The researchers in this study found a significantly higher peripheral blood level in those patients with poor erectile response, suggestive of veno-occlusive dysfunction. On rare occasions patients experience systemic side effects from papaverine intracorporal injections, including dizziness, diaphoresis and cold sweats, which may be the result of either a vaso-vegal reflex or hypotension from the vasodilatory effect in patients with veno-occlusive dysfunction.

Primary care physicians are not trained in handling this complication - it occurs in less than 2 percent of patients - and ordinarily should not be managing patients with intracorporal injections. However, a prolonged erection (24-36 hours) can produce more intracorporal fibrosis, and additional problems of erectile dysfunction. Priapism induced by intracorporal injections can usually be treated promptly and successfully by the urologist in the emergency room. This helps constrict blood vessels, and prevents their sustained dilation and prevents the persistent erection. If taking Sudafed does not cause a return to the flaccid state, the patient has to come to the emergency room where the urologist irrigates the erectile cylinders with a very dilute epinephrine solution.