What types of injections are used to treat ED?
Oral medications don't work for everyone. Many men may be prescribed medicines that go directly, via injection, into the penis. Injection therapy may use a single drug or a combination of drugs. Single drug injection therapy uses alprostadil, a type of prostaglandinE1 (PGE1), and is called either Caverject® or Edex®. Combination therapies, called "bi-mix" (for 2 drugs mixtures) or "tri-mix" (for 3 drugs mixtures), are a mixture of either two, or all three, of the following most commonly used drugs: papaverine, phentolamine and/or alprostadil. Not all bi-mix or tri-mix medications are identical - the amount of the individual drugs may vary from pharmacy to pharmacy.
Alprostadil is a vasoactive agent that is a synthetic version of the chemical prostaglandin E. This chemical helps relax the smooth muscle tissue in the penis to enhance blood flow needed for an erection.
Papaverine and phentolamine also belong to this group of medicines called vasodilators (drugs that relax smooth muscle tissue, causing arteries to open and allowing an influx of blood flow).
Most men who do not respond to oral drug therapies used to treat ED find injection therapies to be effective. Success rates with self-injection are roughly 85 percent of patients. Injections may also be helpful for men who are taking other medications, such as oral nitrates, that should not be used at the same time as some oral medications for ED.
Is the use of injections to treat ED new?
Injection therapy for the treatment of ED is not a new treatment. It was first introduced in the early 1980s. Papavarine was the first substance used and studied extensively in the 1980s. Injection therapies are still in widespread use for the treatment of ED and are a safe and reliable alternative to other ED treatments.
Only Caverject and Edex are FDA approved for use. Compounding pharmacies mix the other combination therapies and because no specific pharmaceutical company has the licensing rights to the combinations, FDA studies have never been conducted, and likely never will, to determine their exact safety and reliability. These combination agents, however, have been used for more than a decade longer than Caverject and Edex and are just as safe and probably more effective in most men.
How are the injections administered?
Penile injections should be coordinated by a urologist. Injection treatments involve the injection of medication into the base of the penis (the part of the shaft furthest from the head of the penis) approximately 5-10 minutes before sexual activity. The injected medication causes blood vessels within the penis to widen, or dilate, which increases blood flow to the penis and causes an erection. Erections from injection therapies are commonly 30 minutes in duration. The needle used is a 29-gauge needle (tiny - like that used by diabetics injecting insulin for sugar control). Most men describe the sensation like 'pulling a hair out of the back of their hand'.
Although the thought of an injection can be unpleasant, injection is a quick and easy technique to learn. The injection method is highly successful letting many men experience an erection rigid enough for intercourse. Injections should not be used more than 3 times per week. Patients need to be trained in the technique of penile injections and these training sessions also allow the physician to figure out a safe starting dose of injection medication.
It is always best to speak with a physician or trained health professional to discuss the proper use of any prescribed treatment.
What are the side effects of injections used to treat ED?
The greatest concern about using injection therapy is the possibility of developing prolonged erections (lasting longer than 4-6 hours). This condition is known as priapism and can cause permanent damage to the erection tissue of the penis. Priapism can be avoided by carefully dosing the medication, which should be coordinated by your urologist (see Fact Card on Avoiding And Treating Priapism).
In general, minor side effects that may occur with penile injection therapy include:
- Mild bruising over the site of injection: this can be avoided by pressing over the injection site for 3 minutes (6 minutes if you are using a blood thinner).
- Penile pain: while uncommon, this occurs more commonly in men using alprostadil containing injection agents. It is most common in men with diabetes and following radical prostatectomy surgery.
- Swelling at the site of injection: this usually happens when some of the medication is discharged under the skin and usually occurs with poor technique.
How much do the injections cost?
The cost per injection for alprostadil (Caverject or Edex) alone can be expensive if insurance carriers do not cover it. The injection mixtures of alprostadil, phentolamine and/or papavarine, are generally less expensive option. Treatment and medication coverage by healthcare insurance varies from one insurance provider to the next, as well as from one plan to the next. Therefore, it is best to contact the individual provider in order to determine which treatments for ED are covered by insurance.