Myron I. Murdock, M.D., F.A.C.S.
Injectable Vasoactive Drugs
The vasoactive drugs that are available for injection therapy include Prostaglandin E-1 (PGE-1, Caverject, Edex), papaverine, Regitine, and vasoactive intestinal polypeptides (VIP). Combinations such as: Bimix: papaverine plus Regitine, or Trimix: (papaverine plus Regitine plus prostaglandin ), are sometimes used.
The drugs are injected, using a small gauge needle, at the base of the penis, directly into the corpora cavernosa, two spongy rods that make up the erectile bodies of the penis. Pain sensation is minimal at this point.
The drugs are injected immediately prior to sexual activity, taking about five to ten minutes to be active, and lasting anywhere from one to two hours. They are extremely effective and work in more than 95% of patients. Contrary to what most people think, the base of the penis has minimal pain fibers and injection into the base of the penis at the two or ten oclock position causes minimal to no discomfort. For those men who are unable to place a needle directly into the body an auto injector is available. The major complications of intracavernosal prostaglandin includes penile discomfort in 3% of cases, rare priapism, and even rarer, injury to the urethra.
Recently a self contained, injectable administration unit has been introduced: the Ompulse system by Pfizer
Caverject, a prostaglandin manufactured by the Pfizer, was the first drug to be FDA approved for the treatment of impotence.
Prior to the widespread use of prostaglandin, combinations of papaverine and Regitine were utilized in the United States. In circumstances in which there is penile pain with injectable prostaglandin, papaverine and Regitine are still utilized. On some occasions papaverine plus Regitine works better than prostaglandin and vice versa. The major problems with papaverine and Regitine are an erection that will not disappear, i.e., priapism and their occasional negative effect on the liver. They cannot be used in patients with chronic liver disease.
On rare occasions when prostaglandin alone or papaverine and Regitine are not effective, the three are combined into what is called Trimix which may be more effective.
Vasoactive intestinal polypeptides (VIP) have been researched in the Scandinavian countries for injection in the treatment of impotence. This drug has not been approved in the United States, it is expensive and not easily available, and it also causes penile discomfort.
MidAtlantic Urology Associates LLC
Formerly Werner-Francis Urology Associates LLC
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