Alprostadil (Caverject, Edex and Prostin VR)

What is Alprostadil and What Does it Treat?

Alprostadil is a prostaglandin (PGE-1) used to treat erectile dysfunction. Erectile dysfunction, also sometimes referred to as impotence, is the inability of a man to develop or maintain a penile erection that is sufficient for successful sexual activity. An erection is caused by the effect of blood entering and remaining within the spongy bodies of the penis known as the corpus cavernosum. The process of that blood entry into the penis is initiated when neurological signals travel from the brain to penile nerves. Those signals are commonly called sexual arousal and are the result of touch, psychological stimulation, or both.

Erectile dysfunction, such as that which may be treated by alprostadil, is often caused by cardiovascular disease, diabetes, neurological problems, hormonal imbalance, and side effects of prescribed medications. Psychological impotence is when a patient cannot obtain or keep an erection due to thoughts or feelings. While this form of erectile dysfunction is less frequent, it is still treatable. Regardless of the cause, erectile dysfunction can be frustrating and psychologically damaging for the man and equally damaging to the relationship with his sexual partner.

Like other prostaglandins, alprostadil works to increase blood flow to the penis by relaxing penile muscles and expanding blood vessels. When blood vessels are expanded, blood flows more freely to the penis and an erection is enabled. The erection is reversed when the alprostadil wears off and blood flow is returned to normal.

Available Forms of Alprostadil

Caverject, Edex, MUSE, and Prostin VR are brand-name versions of alprostadil. Prostin VR Pediatric is the version of alprostadil used to improve blood flow in newborn babies with genetic heart conditions. MUSE, Caverject, and Edex are used to treat erectile dysfunction in men through personal injection in the penis at the time when sexual activity is desired.

Alprostadil generic is also available to patients using alprostadil for erectile dysfunction. The downside of the generic version is that it must be mixed by a compounding pharmacy. The generic version is much less expensive to the patient than the prepared forms of Caverject, Edex, and MUSE. When patients wish to use the generic form, the premixed quantity must be loaded into a syringe and self-injected according to doctor instructions.

MUSE Urethral Suppositories are the suppository form of alprostadil, while Caverject and Edex are injectables. MUSE pellets are inserted into the penis about ten minutes before desired sexual activity. Also used just before sexual activity, Caverject and Edex are injected directly into the corpus cavernosum of the penis by the prescribed patient.

A newer form of alprostadil is available in Europe and the United Kingdom. This version is showing promise for possible integration into the United States availability, once it passes through the Food and Drug Administration. The European-UK alprostadil is a topical cream that has far fewer side effects than Caverject and Edex injectables and MUSE urethral suppositories.

Who Should Not Use Alprostadil?

Alprostadil does have some potential for negatively affecting people who:

  • Are allergic to its ingredients
  • Have blood disease like sickle cell anemia, another sickle cell trait, leukemia, other blood problems
  • Have multiple myeloma or other bone marrow problems
  • May be at risk for priapism (a prolonged, painful erection)
  • Have penile problems like Peyronie’s disease, fibrosis, deformity, or an implant
  • May have other physical reasons to avoid sexual intercourse

Some conditions may or may not prohibit the safe use of alprostadil. For these, the doctor is the best source for determination of any possible risk:

  • Are pregnant, planning a pregnancy, or breastfeeding
  • Are on other medications, whether prescription or non-prescription
  • Have allergies, whether to medications, food, or other
  • Have infection or inflammation of your penis
  • Have urinary tract or kidney problems
  • Have a history of painful or prolonged erections
  • Are taking any other erectile dysfunction treatments
  • Have blood-borne diseases like hepatitis or HIV
  • Are taking medicines that may interact with alprostadil

How to Use Alprostadil

Erectile dysfunction treating doctor is the best resource for how to properly use alprostadil and its name brand formulations of Caverject, MUSE, and Edex. Pharmacists can provide additional information about how the medication prescribed must be taken and patient leaflets are available through the pharmacy.

Below are some additional points to consider when using alprostadil:

  • Alprostadil produces an erection through injection to the penis.
  • The prescribing doctor should demonstrate the use of alprostadil.
  • You should not use alprostadil contaminated by particles, if it is cloudy, discolored or if the cartridge is damaged in any way.
  • Alprostadil should be used within 24 hours after mixing.
  • Each vial should be used for only one dose, and leftover medicine should not be reused.
  • The medicine will start to work within minutes of injection and will last for a half-hour to an hour.
  • Use should not exceed one dose per 24 hours or three doses per week.

Safety and Precautions for Alprostadil Use

Alprostadil and associated brands Caverject, MUSE, and Edex have been known to cause dizziness, which may be worsened with alcohol consumption or when combined with other medication. Patients should not drive or engage in any dangerous activity until personal reaction to alprostadil has been determined. The recommended dosage should never be exceeded without doctor guidance.

If erection resulting from alprostadil is painful or endures for more than four hours, medical attention must be immediately sought. Such conditions can lead to permanent impotence.

Alprostadil does not protect against sexually transmitted diseases or pregnancy. Blood-borne diseases such as HIV and hepatitis B can still be spread with the use of alprostadil.

Female sexual partners of alprostadil users may experience some vaginal dryness or painful sensations. The use of a water-based lubricant during sexual intercourse may help with these concerns. Although alprostadil is not approved for use by women, it is not known if alprostadil can cause harm to a fetus or if it is found in breast milk.

Alprostadil should only be used by the patient to whom it is prescribed. A pharmacist may provide guidance or instruction on the proper disposal of unused medicine. Printed information from the pharmaceutical company contained with your prescription can also provide additional precautions and guidance for brand name forms of alprostadil, including Caverject, MUSE, and Edex.

Side Effects of Alprostadil

Although many users of alprostadil suffer no side effects or have only minor ones, mild bleeding at the injection site may occur. Mild to moderate genital pain may also be experienced on alprostadil. If those effects are seen, the prescribing physician should be consulted.

There is a chance for more serious side effects, although they are rare. Although this is not a complete list, some of those may be:

  • Severe allergic reactions, such as rash, itching, breathing problems, hives, tightness in the chest, oral swelling, facial swelling
  • Abnormal ejaculation
  • Blood from the tip of the penis or in urine
  • Urinary changes, such as in the amount of urine passed
  • Chest pain or unusual heartbeat
  • Penile curving or pain
  • Dizziness or fainting
  • Painful or prolonged erection
  • Penile redness, lumps, swelling, tenderness, discoloration, numbness, inflammation, or strange sensations
  • Severe or continuing bleeding or bruising at the location of the injection
  • Leg vein swelling
  • White patches or discharge from the penis
  • Pain, swelling, or redness at the injection location

Uncommon and even rare side effects of using alprostadil include curving of the penis with erectile pain, an erection of four to six hours or longer and testicular swelling or pain. If too much medicine has been absorbed into the body, dizziness, fainting, pelvic pain or flu-like symptoms may occur.

Some side effects are minor and do not require medical attention, as they are indicative of the body’s adjustment to alprostadil. It is common to experience short-term bleeding or pain at the injection site, mild bleeding or stinging at the urethra in alprostadil suppository use, or a painful erection.

It is rare for female sexual partners to experience itching or stinging of the vagina, but that may be experienced if the female has not had recent or frequent intercourse.

Storage of Alprostadil

Alprostadil should be stored unmixed at 77 degrees Fahrenheit. Alprostadil may be kept briefly at temperatures between 59 and 86 degrees, but should never exceed 86 degrees. Alprostadil already mixed may be kept for 24 hours below 77 degrees. Alprostadil should never be refrigerated or frozen and must be kept away from heat, moisture, and light. It is best to not store in the bathroom and must be kept away from children and pets.


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