Self-Injection Therapy for the Treatment of Erectile Dysfunction

CHAPTER 122 Self-Injection Therapy for the Treatment of Erectile Dysfunction



Robert E. James, James R. Palleschi


Significant advances have been made in the diagnosis and treatment of erectile dysfunction. Although the introduction of oral drugs has decreased the need for and the use of injection therapy, it is still indicated in some patients. The self-injection of vasoactive agents into the corpora cavernosa now enables many patients to resume satisfactory sexual activities without surgery.


Oral medications (sildenafil, tadalafil, and vardenafil) are most effective in patients with mild to moderate impotence. This category would include men who are able to obtain a good erection but cannot maintain it and those men who have an erection that is at least a 5 out of 10 in rigidity, where “10” is defined as the best erection they can remember.


The transurethral form of alprostadil (MUSE) is most effective in men who have difficulty maintaining an erection and in those who have a partial erection, or 5 out of 10 in rigidity.


Despite the advances in the treatment of erectile dysfunction, vacuum erection devices remain an option or adjunct. These devices are attractive to patients who have failed oral therapy and decline or fail intraurethral or intracavernosal alprostadil. Patients using intracavernosal therapy who want to have intercourse more than three times a week usually meet their goal by using vacuum erection devices (see Chapter 125, Vacuum Devices for Erectile Dysfunction).


In the treatment of moderate to severe erectile dysfunction, intracavernosal therapy with vasoactive agents still has a very important role.


In July of 1995, the U.S. Food and Drug Administration (FDA) approved injectable alprostadil (prostaglandin E1 [PGE1]) for the treatment of organic erectile dysfunction. The American Urological Association’s guidelines for the treatment of erectile dysfunction recommend alprostadil as the drug of choice, and it is the only intracavernosal vasoactive agent approved by the FDA.


There is also papaverine hydrochloride, a nonspecific smooth muscle relaxant. In addition to alprostadil, which is a vasodilator and a smooth muscle relaxant, papaverine hydrochloride may be used with phentolamine mesylate, a smooth muscle relaxant that enhances the effect of papaverine. For several years these agents have been used extensively for impotence, although this remains an unlabeled indication.


These vasoactive agents induce an erection by increasing arterial blood flow, relaxing the sinusoidal spaces within the cavernosal tissue, and increasing venous resistance. An excellent erection that lasts for 30 to 90 minutes usually occurs in patients with mild to moderate arterial insufficiency, mild to moderate venous incompetence, psychogenic impotence, neurogenic impotence, and medication-induced impotence.



Indications



• Impotence resulting from arterial insufficiency.

• Impotence resulting from mild to moderate venous incompetence.

• Psychogenic impotence. (Patients with performance anxiety may be treated with counseling, oral agents, short-term intracavernosal agents, or a combination of these methods.)

• Neurogenic impotence.

• Medication-induced impotence, when drug therapy cannot be altered or terminated.

• Diagnostic erection.

• Intolerance to or ineffective oral drugs.


Contraindications



• Blood dyscrasia, coagulation disorder, or anticoagulation drug therapy

• Unstable cardiovascular disease

• Impaired manual dexterity or vision

• Presence of a prosthetic penile device

• Valvular heart disease

• Intolerance to the test dose of the vasoactive agent

• Patients taking monoamine oxidase (MAO) inhibitors

• Patients with a propensity toward secondary forms of priapism, such as individuals with sickle cell disease or trait, leukemia, and multiple myeloma

NOTE: If a physician elects to use intracavernosal pharmacotherapy to treat erectile dysfunction in men with Peyronie’s disease, a special informed consent is advised.



Equipment



• l- to 3-mL syringes with image-inch, 27- and 30-gauge needles

• Alcohol swabs

• Vasoactive agents
• Papaverine HCl 30 mg/mL is available in 10-mL multidose vials.

• Papaverine and phentolamine solution: Inject 5 mg (or 10 mg) of phentolamine (Regitine; Novartis, East Hanover, NJ) into a 100-mL vial of papaverine 30 mg/mL. The (approximate) concentrations will be papaverine 30 mg/mL and phentolamine 0.5 or 1.0 mg/mL.

• PGE1 (alprostadil): There are two proprietary forms of injectable alprostadil for the treatment of erectile dysfunction available in the United States: Caverject and Edex (Schwarz Pharma, Mequon, Wis). The clinical dose range varies from 2 to 40 µg per injection. Each manufacturer has provided alprostadil in a ready-to-use, easily assembled syringe that does not require refrigeration. The syringes are meant for single use only.

• PGE1 (alprostadil) is also available in 1-mL ampules from Upjohn (Kalamazoo, Mich) as Prostin VR Pediatric 500 mg/mL. For the desired concentration, inject 0.2 mL of this preparation into each of five 10-mL vials of bacteriostatic normal saline for injection. Each vial will contain PGE1 10 mg/mL.

Bennett and coworkers in 1991 developed a trimix combination therapy for the treatment of erectile dysfunction. This three-drug mixture contains 2.5 mL of papaverine (30 mg/mL), 0.5 mL of phentolamine (5 mg/mL), and 0.05 mL of alprostadil (500 µg/mL) for intracavernous injection. Most patients require less than 0.25 mL per injection.


Open vials or compounded solutions should be refrigerated to maintain sterility and effectiveness. A 30-day expiration date is recommended; however, sufficient effectiveness has been reported for up to 3 months.


α-Adrenergic agents will cause vasoconstriction and thus will usually result in prompt detumescence should priapism occur. Some of the available agents include ephedrine sulfate, epinephrine, and phenylephrine hydrochloride (Neo-Synephrine). (See the “Treatment of the Persistent Erection [Priapism]” section for dilutions and use.)



Preprocedure Patient Preparation


Discuss the self-injection program, alternatives, and potential complications with the patient and, when possible, his partner. Patients using this program may experience bruising at the injection site and local or systemic infection (<0.05% incidence). Chronic fibrosis at the injection site may occur with repeated injections, and this may result in pain or penile curvature. Papaverine may elevate the results of liver function tests. Consequently, patients should obtain pretreatment liver function tests and should be retested every 3 months while using papaverine. If the liver function test values begin to rise, the medication should be discontinued. If the initial liver function test results are elevated, use PGE1 instead of papaverine. Approximately 20% of patients using PGE1 may experience an ache in the penis that may last for several hours and that may recur with each injection. Priapism, an erection lasting longer than 4 hours, may occur in up to 10% of patients receiving any of the vasoactive agents, but it reportedly occurs less frequently with PGE1. Systemic side effects, such as dizziness and orthostatic hypotension, occur in 2% of patients receiving these vasoactive agents and are believed to be secondary to penile venous incompetence.


Instruct the patient to contact the physician if he experiences a significant erection that persists for more than 4 hours. This condition will need to be treated promptly to prevent intracorporeal fibrosis and failure to respond to future therapy.

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May 14, 2017 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Self-Injection Therapy for the Treatment of Erectile Dysfunction

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