Penile injection therapy for erectile dysfunction (ED) was first introduced in the early 1980s, and has been used by hundreds of thousands of men. It was more widely used before the introduction of medications such as Viagra, but it is still used by many men today.
How is penile injection therapy done?
In penile injection therapy, the medication is injected directly into the inner part of the penis through a very small "insulin-style" needle. The medication is not injected under the skin, but must be injected into the inner part of the penis that fills with blood during an erection. The injection can be performed on either side of the penis, and the medication will spread throughout the entire penis. A firm erection develops in 10-to-15 minutes and lasts 30-to-60 minutes. The amount that needs to be injected to produce a strong erection varies from person to person, and patients inject the smallest volume necessary to acheive an adequate erection. The medication can produce an erection even if a man is not aroused, but sexual arousal assists the medication in producing a good erection.
Injection therapy typically uses one or more drugs which must be prescribed by a doctor, usually a urologist. The man directly injects the drugs into the side of his penis when he wishes to have an erection. The drugs tell the blood vessels in the penis to open, and increased blood flow into the penis creates an erection. The erection is exactly the same as a natural erection because the penis is being pumped full with blood, just like during a natural erection.
When men are interested in penile injection therapy, the first trial injection is performed by the urologist in the office to be sure that the patient has no side effects. If a patient wishes to do injections at home he will come back for a second visit, during which the patient is taught how to do the injections. Patients can then try the medications at home.
Who are good candidates for penile injection therapy?
Penile injection therapy can be a good alternative for the 30-to-40 percent of men who fail to get adequate results from oral medications. The best treatment for erectile dysfunction, however, depends on many things. These include a man's health and personal and physical tolerance for the treatment. A man with ED should involve his spouse or partner and his doctor in the treatment decision.
Some conditions rule out the use of injection therapy. These can include:
- Allergy to the injected medications
- Abnormally formed penis
- Peyronie's disease or penis angulation
- Carvernosal fibrosis
- Diseases that might result in prolonged erection, such as sickle cell anemia
- Men who take Coumadin or other blood thinners
Risks of injection therapy
- Pain- the pain of the needle injection is minimal for most men, but 15 percent of men will have aching pain in the penis for 30-60 minutes after injection. Sometimes a change in medications is effective in reducing pain
- Bruising- this is usually minimal and of no consequence.
- Prolonged erection (priapism) - this is the most serious side effect and affects less than 5 percent of men. Men most likely to experience priapism are men with spinal cord injury, men younger than 40, or men who inject more than once in 24 hours. If a man has a fully rigid erection for more than 4 hours it will become painful, and after six hours priapism can damage the blood vessels in the penis. If a patient has a fully rigid erection three hours after injection, he should call his doctor or go to the nearest emergency room.
- Penile Scarring- around 5 percent of men who perform injection therapy will develop scarring inside the penis which may cause bending of the erection.
- Infection- it is extremely rare to have infection after penile injection therapy.
The most common medications used for injection therapy are Papavarine, Phentolamine and alprostadil. Most men use alprostadil, which is also known as prostaglandin E. This medication can be pre-mixed, in which case a man simply draws the right amount of medication into a syringe for injection. It can also be purchased in a kit which contains a freeze-dried pellet of medication in a special syringe. The pre-mixed alprostadil is less expensive than the freeze dried kits, but must be kept in a refrigerator or it will lose its strength. The "kits" can be kept at room temperature and are very convenient for men who travel. The most commonly used brand of freeze-dried kit is called Caverject. Patients who do not get an adequate erection with alprostadil, or who have pain after injection, may use a combination of papaverine, phentolamine, and alprostadil called tri-mix. This combination is prepared at specialty pharmacies and shipped to your home.