Impotence is a common disorder than can usually be successfully treated by intracavernous injection of vasoactive medication. This is a technique where a vasodilator medicine is injected into the part of the penis having the least sensation. Three principal medications are used. These include Prostaglandin E1, Papaverine, Phentolamine, or a mixture of two or three agents. When used alone, Papaverine often produces incomplete results in those having impotence from non-neurologic causes. Prostaglandin E1 (Caverject or Edex) is the most commonly used injection medicine for impotence. Every patient responds to a different dosage of the medication.
Because of this, during the first office visit, your physician will inject you with an initial test dose of medication. You will be allowed to leave the office but should pay careful attention to the duration of effect and completeness of rigidity. When seen at the next office visit, the dose of the second injection is based upon the results achieved with the first.
During the second visit, you will inject yourself with our supervision. Injections are given into the side of the mid-penile shaft. This location is the least sensitive part of the penis. Most men using this technique are surprised with how little discomfort is produced by the needle. Depending on the result obtained from the first injection, after the second injection, you may be ready to try the technique at home. Not uncommonly, however, three or four visits may be necessary to decide the optimal dose. Determining the optimal dose of medication is important to prevent prolonged erection.
Prolonged erection, or priapism, occurs when an erection has persisted more than four hours. This process may become very uncomfortable and can lead to permanent damage of the cavernosal tissue. Priapism can result in serious injury to the erectile mechanism that may prevent future erections by any method. Priapism is uncommon, occurring in approximately 1% of people using injections. However, most of those cases occur in the first few injections. For that reason, we begin with a low initial dose and slowly increase the dosage until an optimal response is achieved.
Patients often wonder why we cannot prescribe the medication and let them try the medicine at home. Although attractive, this regimen leads to unacceptably high rates of priapism. If you are one of the few patients who experience an episode of priapism, it may be reversed with the first few hours. Any erection persisting longer than four hours, requires immediate return to the urology office in the Vanderbilt Clinic or the Vanderbilt Emergency Room after business hours. Medications may be injected into the penis that cause reversal of erection. Detumescence (gradual shrinking of an erection) within four to six hours prevents penile injury.
Another possible complication of injection therapy is scarring of the inner lining of the penis. This may occur with repeated injections over several years. Fortunately, this is not common, occurring in less than 5% of patients. Simple scarring is not problematic. Only when the scarring becomes significant enough to cause penile curvature do most people notice. To prevent scarring, we recommend alternating the site of the injection. There is also some evidence that Prostaglandin E1 is less prone to produce scarring than Papaverine. Because of this and the decreased incidence of priapism with the drug, we currently favor Prostaglandin E1 (Caverject) over other medications.
Intracorporeal injections produce a rigid, normal appearing erection that lasts 30 - 45 minutes. Erection often persists following ejaculation. The dosage of medication can be decreased to shorten the duration of erection. However, we often find that incomplete rigidity is obtained if the dose produces less than a 30 minute erection. More than 90% of patients obtain results satisfactory for normal intercourse using intracavernous injections.
The cost and availability of vasoactive substances are important to know. Although probably the most effective medication, Prostaglandin E1 is also the most expensive. One bottle of compounded medication costs approximately $80.00. This is usually enough to provide for 5 to 15 injections. Looked upon as a per dose basis, the cost becomes reasonable. Prostaglandin E1 has been released in a preparation specifically marketed for causing penile erection. This medication, Caverject, is about $20.00 per dose. The Papaverine and Phentolamine mixture costs approximately $60.00, but can be difficult to obtain. Both premixed Prostaglandin E1 and Papaverine/Phentolamine should be refrigerated. There is considerable laboratory evidence that if always kept refrigerated, the medication can remain active for up to three months. Caverject and Edex, the other Prostaglandin E1 preparations, come as a powder that does not require refrigeration and has a long shelf life. The medication is reconstituted with saline solution immediately before use.
Most drug stores do not sell the compounded medications. Preparation of these medications requires a special facility. The pharmacy on the first floor of The Vanderbilt Clinic dispenses the medication. Caverject and Edex are available at most local drug stores.
Intracorporeal injection is a surprisingly easy and effective treatment option for impotence. During your clinic visits you will be taught to do the procedure and the optimal dosage of medication will be determined. It is important not to use more than the recommended amount of medicine to avoid prolonged erection. Careful adherence to a few basic rules will usually allow you to have normal sexual activity.