Intracavernosal injection (ICI) therapy is a treatment for erectile dysfunction (ED) that involves administering medication directly into the penis to produce an erection. This method is often considered when oral medications have not been successful. ICI therapy has been a treatment option since the early 1980s and can be tailored to individual patient needs.
Mechanism of Action
The shaft of the penis contains two sponge-like chambers called the corpora cavernosa. When sexually aroused, nerve signals cause these chambers to relax and fill with blood, leading to an erection. In men with erectile dysfunction, this process may be impaired.
ICI therapy bypasses these issues by delivering medication directly to the corpora cavernosa. The injected drugs are vasodilators, which widen blood vessels and cause the smooth muscles in the penile arteries and corpora cavernosa to relax.
This relaxation increases blood flow into the penis while compressing the veins that drain blood away. The result is a firm erection that develops within 5 to 15 minutes and does not always require sexual stimulation.
Medications Used in Therapy
Several different medications are used in intracavernosal injection therapy, often in combination to maximize effectiveness. The most common is Alprostadil, a synthetic form of prostaglandin E1. When injected, Alprostadil induces vasodilation, increasing blood flow to the penis.
In many cases, a single medication may not be sufficient, so compounded mixtures are used. One formulation is Bi-Mix, which contains papaverine and phentolamine. Papaverine is a vasodilator, while phentolamine is an alpha-blocker that also promotes blood vessel relaxation.
A more potent formulation is Tri-Mix, which combines all three medications: papaverine, phentolamine, and Alprostadil. This combination is often effective for individuals who do not respond to single-drug or Bi-Mix therapies.
The Injection Process
Self-administering an intracavernosal injection is a manageable procedure that requires careful instruction and practice. First, wash your hands thoroughly and clean the top of the medication vial with an alcohol swab. Using a sterile, single-use insulin-type syringe, draw the prescribed dose of medication from the vial and expel any air bubbles to ensure accurate dosing.
With the medication prepared, select an injection site on the side of the penile shaft, avoiding the top, bottom, and head where nerves and the urethra are located. To prevent the formation of scar tissue, it is important to alternate the injection site from one side to the other with each use. Hold the penis firmly and slightly stretched to create a stable target.
The needle is inserted at a 90-degree angle into the spongy tissue of the corpora cavernosa, and the medication is injected slowly. After the full dose is delivered, remove the needle and apply firm pressure to the injection site for one to two minutes to prevent bleeding or bruising. An erection should begin to form within 5 to 15 minutes.
Potential Side Effects and Complications
The most common side effects are localized to the injection site and may include mild pain, bruising, or minor bleeding. Some individuals also experience a sensation of warmth or aching in the penis as the erection develops. These effects are temporary and diminish with proper injection technique.
A more serious complication is penile fibrosis, the formation of scar tissue at injection sites over time, which can lead to penile curvature. Rotating injection sites regularly helps mitigate this risk.
Another significant risk is priapism, a prolonged and often painful erection that lasts for several hours. An erection lasting longer than four hours is a medical emergency that requires immediate attention. If left untreated, priapism can damage penile tissues and lead to permanent ED. If the erection persists, medical intervention is necessary to drain the trapped blood.
Determining Candidacy for Treatment
This treatment is often recommended for individuals with erectile dysfunction who have not had success with or cannot take oral medications. This may include men with certain medical conditions, such as diabetes or those who have undergone a radical prostatectomy where nerve damage can affect erectile function. A patient’s manual dexterity and vision are also considered, as the ability to safely prepare and administer the injection is necessary. A willingness to learn and adhere to the proper injection technique is also a factor.
The initial dose is administered in a clinical setting under medical supervision to determine the appropriate dosage and to train the patient. This allows the provider to monitor for any immediate adverse reactions and ensure the patient is comfortable with the procedure.