General Information

edex is an injectable formulation of alprostadil, an endogenous substance known as prostaglandin E1 (PGE1), which is a smooth muscle relaxant.  

edex is specifically indicated for the treatment of erectile dysfunction due to neurogenic, vasculogenic, psychogenic, or mixed etiology.

edex is supplied as an injection for intracavernous administration. The dosage range of edex for the treatment of erectile dysfunction is 1 to 40 mcg. The intracavernous injection should be given over a 5 to 10 second interval. 

Initial Titration in Physician's Office

Erectile Dysfunction of Vasculogenic, Psychogenic, or Mixed Etiology:

• Dosage titration should be initiated at 2.5 mcg of alprostadil. If there is a partial response, the dose may be increased by 2.5 mcg to a dose of 5 mcg and then in increments of 5 to 10 mcg, depending upon erectile response, until the dose that produces an erection suitable for intercourse and not exceeding a duration of 1 hour is reached. If there is no response to the initial 2.5-mcg dose, the second dose may be increased to 7.5 mcg, followed by increments of 5 to 10 mcg. The patient must stay in the physician's office until complete detumescence occurs. It there is no response, then the next higher dose may be given within 1 hour. If there is a response, then there should be at least a 1-day interval before the next dose is given.

Erectile Dysfunction of Pure Neurogenic Etiology (Spinal Cord Injury):

• Dosage titration should be initiated at 1.25 mcg of alprostadil. The dose may be increased by 1.25 mcg to a dose of 2.5 mcg, followed by an increment of 2.5 mcg to a dose of 5 mcg, and then in 5-mcg increments until the dose that produces an erection suitable for intercourse and not exceeding a duration of 1 hour is reached. The patient must stay in the physician's office until complete detumescence occurs. If there is no response, then the next higher dose may be given within 1 hour. If there is a response, then there should be at least a 1-day interval before the next dose is given.

At-Home (Maintenance Therapy) Dosing Instructions

• The first injections of edex must be done at the physician's office by medically trained personnel. Self-injection therapy by the patient can be started only after the patient is properly instructed and well trained in the self-injection technique. The physician should instruct the patient to discard any needles which become bent during the self-injection procedure as these needles may break. The physician should make a careful assessment of the patient's skills and competence with the self-injection procedure. The intracavernous injection must be done under sterile conditions. The site of injection is usually along the lateral aspect of the proximal third of the penis. Visible veins should be avoided. The side of the penis that is injected and the site of injection must be alternated. The injection site must be cleansed with an alcohol swab before injection.
• The dose of edex that is selected for self-injection treatment should provide the patient with an erection that is satisfactory for sexual intercourse and that is maintained for no longer than 1 hour. If the duration of erection is longer than 1 hour, the dose of edex should be reduced. The lowest effective dose should be used at home. Self-injection therapy for use at home should be initiated at the dose that was determined in the physician's office. Dose adjustment may be required and should be made only after consultation with the physician.

Mechanism of Action

Alprostadil (PGE1) is one of the prostaglandins, a family of naturally occurring acidic lipids with various pharmacological effects. Endogenous PGE1 is derived from dihomo-gamma-linolenic acid, a fatty acid found within the phospholipids of cellular membranes. As an endogenous substance, PGE1 exerts its biological effects either directly or indirectly by regulating and modifying the synthesis and effects of other hormones and mediators. Alprostadil induces erection by relaxation of trabecular smooth muscle and by dilation of cavernous arteries. This leads to expansion of lacunar spaces and entrapment of blood by compressing the venules against the tunica albuginea, a process referred to as the corporal veno-occlusive mechanism.

Clinical Results

After self-injection of EDEX, 97% to 99% of patients with erectile dysfunction achieved erections sufficient for intercourse. In the studies of 1,065 people, patients performed more than 15,400 self-injections. More than 90% of patients reported satisfactory responses in both patient and partner satisfaction.

Side Effects

Adverse effects associated with the use of edex may include, but are not limited to, the following:

• local site reaction
• penile pain
• prolonged erection/priapism
• hematoma/ecchymosis

Clinical Trial Results

The FDA approval of edex was based on two studies which enrolled 347 men with a diagnosis of erectile dysfunction due to vasculogenic, neurogenic and/or mixed etiology. Each study consisted of three phases: an in-office dose-titration phase, a two-week double-blind cross-over phase at home, and an open-label at home treatment phase that lasted for 12 months (Study 1) or six months (Study 2). 

During the dose-titration phase, individualized optimum doses of edex were established. Erectile response was measured by the Buckling Test to assess axial penile rigidity. A positive Buckling Test was achieved if the erect penis was able to support an axial load of 1.0 kg without buckling of the penile shaft. During the subsequent two-week double-blind, cross-over phase, patients self-injected edex or placebo at home. Thereafter, patients continued to perform self-injections of open-label edex for six or 12 months, and the occurrence of an erection sufficient for sexual intercourse was documented following each injection.

Study 1: One hundred fourteen men with a mean age of 53 years (range 22 to 65 years) were enrolled in the first phase. The mean optimum dose was 13.8 mcg (range 1 to 20 mcg). Seventy-six percent (87/114) of patients had an erection with a positive penile Buckling Test. Among the 71% (81/114) of patients who entered the placebo-controlled phase, an erection sufficient for sexual intercourse was achieved in 74% (60/81) of patients following edex injection compared to 7% (6/81) of patients following placebo injection. The mean duration of erection following edex was 56.9 minutes compared to 4.0 minutes following placebo. Among the 65% (74/114) of patients who entered the open-label treatment phase, the mean rate of response with an erection sufficient for sexual intercourse was 88.9% through 12 months. The average dose of edex remained essentially unchanged throughout the study duration.

Study 2: Two hundred thirty-three men with a mean age of 59.8 years (range 23 to 74 years) were enrolled in the first phase. The mean optimum dose was 25.9 mcg (range 1 to 40 mcg). Seventy-three percent (171/233) of patients had an erection with a positive penile Buckling Test. Among the 60% (141/233) of patients who entered the placebo-controlled phase, an erection sufficient for sexual intercourse was achieved in 73% (103/141) of patients following edex injection compared to 13% (18/141) of patients following placebo injection. The mean duration of erection following edex was 59.0 minutes compared to 7.6 minutes following placebo. Among the 60% (139/233) of patients who entered the open-label treatment phase, the mean rate of response with an erection sufficient for intercourse was 85.3% through six months. The average dose of edex remained essentially unchanged throughout the study duration.