ED Treatment - Transurethral Agents

Transurethral agents, also called intra-urethral agents, are erectile dysfunction (ED) treatments whose mode of administration is insertion into the urine channel, known as the urethra. The only FDA-approved urethral suppository is called MUSE® (Medicated Urethral System for Erection), which contains the drug alprostadil (also used in the injectable drugs, Caverject and Edex).

Alprostadil (MUSE) belongs to a group of medicines called vasodilators that increase blood flow by causing blood vessels to expand. Once MUSE is inserted and absorbed into the tissue immediately surrounding the urethra (the corpus spongiosum), it is transferred into the erectile chambers (corpora cavernosa) through small veins. The medicine then causes the erectile tissue to relax and allows blood flow to increase. This increased blood flow causes an erection.

MUSE is prescribed in one of four dose strengths (125, 250, 500, and 1000 micrograms), although the lower doses tend not to be effective in the average man with ED. MUSE is usually only recommended as a single daily dose.

MUSE usually begins creating an erection in about five-to-ten minutes. Sexual activity should be attempted within 10 to 30 minutes after using the medicine. It is not uncommon for the erection to continue after ejaculation, although loss of the erection is expected within one hour. A doctor should determine the correct dose of MUSE.

While urethral suppositories are often less intimidating to men than injecting medicines into the penis, inserting them can still be a complex process and should be taught in the clinician's office before a man begins to use MUSE at home.

Each medication packet contains a special applicator. This applicator contains a tiny medicated pellet, roughly the size of a grain of rice.

Before inserting the medication, the man should urinate. The pellet is designed to dissolve in the small amount of urine that remains in the urethra, so urinating first helps the penis absorb the medicine.

Next, the man uses the applicator to insert the pellet approximately one inch into the opening at the top of the penis. To minimize leaking and promote absorption, the patient is also instructed to hold the penis upright and massage gently and to stand, sit or walk for 5 to 10 minutes while the medication is being absorbed and an erection develops.

The most common side effects are pain and minor discomfort in the penis and perineum (area between scrotum and rectum) and dizziness. These side effects are reported in less than 5% and 2% of men, respectively, and often go away during treatment as the body adjusts to the medicine. Because of the potential for dizziness, it is often recommended that the first dose of the agent, particularly 500 or 1000 mgs, be given in the physician's office.

Rare side effects that require a doctor's immediate attention include an erection lasting over four hours (known as priapism) or an erection becoming painful.

When using alprostadil in its suppository form, it is important to use a condom when having sexual intercourse with a pregnant female. Although harm to the fetus is unlikely, using a condom will protect the fetus from exposure to this medicine. If a woman can become pregnant, use of contraceptive methods is recommended because the effects of this medicine on early pregnancy are not known.

Men should avoid using urethral suppositories if they are hypersensitive to alprostadil, have an abnormally-formed penis, or have been advised against sexual activity.

Men who have conditions that make them susceptible to long-lasting erections should also not use MUSE. Examples of such conditions include sickle cell anemia (or trait), leukemia, or multiple myeloma (tumor of the bone marrow).

A man using urethral suppositories should use a condom when having intercourse with a pregnant woman, as it is unclear how the medication may affect a developing fetus.

Some women experience vaginal itching or burning when their partners use urethral suppositories. If a woman has not had intercourse in a long time, she should see her healthcare provider before having sex with a man using urethral suppositories.

Pregnant women should make sure a condom barrier is used during intercourse with a man using urethral suppositories.