Non-oral pharmacologic treatment of erectile dysfunction involves injecting medications into the penis to stimulate erections. This approach is typically used when oral medicines have not been effective. Unlike the oral medications that require erotic stimulation for an erection to occur, the injectable medications used in MS produce an erection regardless of the presence or absence of erotic stimulation.
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| Side Effects Of Penile Injections |
Although many men object to the idea of injecting medication into the penis to simulate erections, the injection is done with a very fine needle into an area at the base of the penis that is relatively insensitive to pain. Men who are particularly resistant to the idea of self-injecting can use an "auto-injector" that works with a simple push-button mechanism.
Most men report very little, if any, pain from this injection. The sensation is best described as similar to being flicked by a rubber band.
Three different injectable medications are commonly prescribed, and several other are under investigation. Prostaglandin E1 (alprostadil; Prostin VR) has been approved by the FDA for the management of erectile problems and is the one used most commonly in MS. This vasodilator and smooth muscle relaxant is the natural substance released by the smooth muscle cells in the penis when a man is sexually excited. Relaxation of smooth muscle in the penis prevents blood from leaving the penis once it enters, allowing erection to occur.
The FDA has also approved alprostadil for use via urethral suppository (MUSE). In this approach, a small plastic applicator inserts the drug into the urethra. The drug is absorbed into penile tissues and stimulates a satisfactory erection in most men who have erectile dysfunction. Approximately one-third of men report some penile discomfort with its use, and priapism can occur m rare instances.
Another drug used for injections, papaverine, is also a smooth muscle relaxant. Papaverine is infrequently associated with pain and is thus a good alternative for any men who experience discomfort with prostaglandin E1. Papaverine has a slightly greater tendency to cause scarring at the injection site. Because papaverine also remains active in the body for a somewhat longer period of time, it is associated with a greater risk of priapism. Although it is commonly prescribed, papaverine has not been approved by the FDA for the treatment of erectile dysfunction.
Phentolamine (Regitine in the United States; Rogitine in Canada) is sometimes used in combination with either prostaglandin E1 and/or papaverine to heighten their effectiveness. Phentolamine is an alpha-adrenergic blocking agent and will not induce erections without the presence of another medication (most frequently prostaglandin E1 and/or papaverine). Depending on the type of symptoms the man is experiencing; his physician may prescribe different combinations of these medications.
Priapism is a potential side effect of any of these treatments, particularly if too much medication is administered. Priapism almost never occurs in individuals who adhere to the prescribed dose of medication and who are properly trained in the injection procedures.
A second potential side effect of penile injections, which is experienced by approximately 7-10% of individuals, is scarring at the injection site. This problem very seldom occurs in men who have been properly trained in correct injection techniques. When scarring does occur, it takes the form of a small nodule in the subcutaneous tissue of the penis. Any man who is self-injecting should be examined by a physician every 3 months for possible scarring. These nodules typically disappear after the injections are stopped. To find out more, you can check out Side Effects Of Penile Injections.