alprostadil
Caverject, Edex, Muse

Available forms
Available by prescription only
Injection (frozen) intracavitary: 10.2 mcg/ml, 20.2 mcg/ml, 40.4 mcg/ml
Sterile powder for intracavernosal injection: 6.15-mcg, 6.225-mcg, 10.75-mcg, 11.9-mcg, 12.45-mcg, 21.5-mcg, 23.2-mcg, 24.9-mcg, 43-mcg, 49.8-mcg vials
Urethral suppository pellet: 125 mcg, 250 mcg, 500 mcg, 1,000 mcg

Indications and dosages
 Erectile dysfunction of vasculogenic, psychogenic, or mixed etiology. Adults: Dosages are highly individualized. For injection: Initial dose is 2.5 mcg intracavernously. If partial response occurs, increase second dose by 2.5 to 5 mcg, and then increase dose further in increments of 5 to 10 mcg until patient achieves an erection (suitable for intercourse but not lasting longer than 1 hour). If initial dose isn’t effective, increase second dose to 7.5 mcg within 1 hour; then increase dose further in 5- to 10-mcg increments until patient achieves an erection. Patient must remain in prescriber’s office until complete detumescence occurs. If patient responds, don’t repeat procedure for 24 hours. For pellet, start initially with lower doses (125 or 250 mcg). Increases or decreases should be made on separate occasions in a stepwise manner until patient achieves an erection that’s sufficient for sexual intercourse.
 Erectile dysfunction of pure neurologic etiology (spinal cord injury). Adults: Dosages are highly individualized. Initial dose is 1.25 mcg intracavernously. If partial response occurs, give second dose of 1.25 mcg and then a third dose of 2.5 mcg; increase dose further in 5-mcg increments until patient achieves an erection (suitable for intercourse but not lasting longer than 1 hour). If initial dose isn’t effective, increase second dose to 2.5 mcg within 1 hour; then increase further in 5-mcg increments until patient achieves an erection. Patient must remain in prescriber’s office until complete detumescence occurs. No more than two doses administered 1 hour apart should be given in 1 day. If patient responds, don’t repeat procedure for 24 hours.

Pharmacodynamics
Corrective action in impotence: A prostaglandin derivative that induces erection by relaxation of trabecular smooth muscle and by dilation of cavernosal 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.

Pharmacokinetics
Absorption: Absolute bioavailability hasn’t been determined.
Distribution: Bound in plasma protein primarily to albumin (81%).
Metabolism: Rapidly converted to compounds that are further metabolized before excretion.
Excretion: Excreted primarily in urine, the remainder in feces.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug, in patients with disposition to priapism (those who have sickle cell anemia or trait, multiple myeloma, or leukemia), and in patients with penile deformation (angulation, cavernosal fibrosis, or Peyronie’s disease). Don’t administer to men with penile implants or for whom sexual activity is contraindicated. Also avoid use in women, children, and neonates. Muse shouldn’t be used for sexual intercourse with a pregnant woman unless the couple uses a condom barrier.

Interactions
Drug-drug. Anticoagulants: Increase risk of bleeding from intracavernosal injection site. Monitor patient closely.
Cyclosporine: Decreases cyclosporine level. Use together cautiously.
Vasoactive drugs: Safety and efficacy when used with other agents haven’t been studied. Such use isn’t recommended.

Adverse reactions
CNS: headache, dizziness, fainting.
CV: hypertension, hypotension, swelling of leg veins.
EENT: sinusitis, nasal congestion.
GU: penile pain, prolonged erection, penile fibrosis, penis disorder, penile rash, penile edema, prostatic disorder, testicular and perineal aching, urethral burning, localized trauma, localized pain, injection site hematoma, injection site ecchymosis.
Musculoskeletal: back pain.
Respiratory: upper respiratory tract infection, cough.
Other: flu syndrome.

Effects on lab test results
None reported.

Overdose and treatment
If intracavernous overdose of drug occurs, patient should be under medical supervision until systemic effects have resolved or penile detumescence has occurred.
 Symptomatic treatment of systemic symptoms is appropriate.

Special considerations
• Patient must have underlying treatable medical causes of erectile dysfunction diagnosed and treated before therapy starts.
• Regular follow-up of patient with careful examination of the penis is strongly recommended to detect signs of penile fibrosis. Discontinue drug in patient for whom penile angulation, cavernosal fibrosis, or Peyronie’s disease develops.
• Monitor patient for hypotension, and adjust drug to lowest effective dose.
• Monitor patient for adverse effects, and discontinue drug immediately if patient develops penile angulation, cavernosal fibrosis, or Peyronie’s disease.
• Female partners of Muse users may experience vaginal itching and burning.
• Intercavernosal alprostadil has been used as an adjunct to different diagnoses of erectile dysfunction and evaluation of the hemodynamic status of erectile tissue.
Breast-feeding patients
• Drug isn’t indicated for use in women.
Pediatric patients
• Drug isn’t indicated for use in neonates or children.

Patient education
• To ensure safe and effective use, thoroughly instruct patient how to prepare and administer alprostadil before beginning intracavernosal treatment at home. Stress importance of following instructions carefully.
• Tell patient to discard precipitated or discolored vials. Reconstituted vial is designed for only one use and should be discarded after withdrawal of proper volume of the solution.
• Instruct patient not to shake the contents of reconstituted vial.
• Stress importance of not reusing or sharing needles or syringes as well as not sharing medication.
• Make sure patient has the manufacturer’s instructions for administration included in each package of alprostadil.
• Tell patient not to change the dose without medical approval.
• Inform patient that he can expect an erection to occur 5 to 20 minutes after drug administration and that standard treatment goal is to produce an erection lasting not longer than 1 hour.
• Warn patient that an erection lasting over 6 hours has been known to occur after alprostadil injection. If this occurs, instruct patient to seek medical attention immediately.
• Tell patient that drug shouldn’t be used more than three times weekly, with at least 24 hours between each use. The maximum frequency of using Muse is two administrations per 24-hour period.
• Review possible adverse reactions with patient. Tell him to immediately report priapism, penile pain that wasn’t present before or that’s increased in intensity, and the occurrence of nodules or hard tissue in the penis.
• Instruct patient to inspect penis daily for redness, swelling, tenderness, or curvature of the erect penis, which might suggest an infection. The patient should call if he suspects infection.
• Remind patient that regular follow-up visits are necessary to evaluate effectiveness and safety of therapy.
• Inform patient that drug doesn’t offer protection from transmission of sexually transmitted diseases and that protective measures continue to be necessary.
• Warn patient that a small amount of bleeding can occur at the injection site. This can increase the risk of transmitting blood-borne diseases, if present, to his sexual partner.
• Caution patient using Muse to use a condom when having sexual intercourse with a pregnant partner; this will also prevent potential vaginal burning and itching in female partner.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use