What is Alprostadil? How does Alprostadil work?

What is Alprostadil?

Alprostadil is a synthetic active ingredient that closely resembles the body’s own prostaglandin E1 (PGE1) substance.

It is used to maintain the ductus arteriosus Botalli in newborns with congenital heart defects, for example, because of its blood circulation-promoting and vasodilating effects. It improves the oxygen supply and, as a result, the baby’s ability to survive until surgical treatment is available in the form of an infusion.

Alprostadil is used to treat chronic arterial occlusive disease stages III and IV, and it is also available as an infusion.

Alprostadil has been used to treat erectile dysfunction (impotence) in men since 1986 because it causes the penis to become erect by relaxing the muscles and expanding the blood vessels.

Typically, oral medications such as Viagra or Cialis are prescribed first. Alprostradil is the first line of defense if nothing else works.

Alprostadil has the advantage of being a reliable and fast-acting medication with few side effects. The patient injects the active substance directly into the erectile tissue of the penis or into the urethra. The proper dosage and application must be determined in advance by the attending physician, and only he has the authority to change them.

How does Alprostadil work?

Alprostadil mimics the action of the body’s own tissue hormone, PGE1, which dilates blood vessels and relaxes muscles, helping to facilitate blood flow to the penis.

On the one hand, the active ingredient expands the blood vessels in the penis and relaxes the muscles of the erectile tissue, so that the blood can flow more easily into the erectile tissue and an erection occurs.

On the other hand, it helps constrict the blood vessels that carry blood away from the penis, restricting blood flow from the penis and maintaining an erection.

As a result, the mechanism of action differs from so-called PDE inhibitors such as Viagra, Cialis, Levitra, or Spedra, so that alprostadil is also successful in the case of nerve damage and does not require sexual arousal.

Duration of action and onset of action of Alprostadil

The effect of alprostadil is usually weaker than that of PDE inhibitors such as Viagra, but it is not dependent on sexual stimulation. Alprostadil is therefore effective in men who have suffered nerve damage in the pelvic or genital area, and PDE inhibitors are ineffective.

Since alprostadil is injected or applied directly into the penis, blood circulation in the glans improves very quickly. A sufficient erection for sexual intercourse is usually available after 5 to 30 minutes, depending on the medication. With a good dosage of the active ingredient, this lasts for up to 60 minutes.

Clinical studies showed that 62 to 93 percent of subjects achieved an erection strong enough to have comfortable intercourse. The injections were more effective than the urethral rods. However, there were also more side effects from the injections.

What side effects of Alprostadil can occur?

Although alprostadil is similar to the body’s own PGE1, side effects can occur. Pain or burning in the penis caused by the injection is the most common. However, this pain disappears fairly quickly with circular movements of the penis.

In addition, bleeding and inflammation can occur at the injection site, the foreskin, the glans, or the urethra. It is therefore important to ensure hygiene and adequate cleaning of the injection site before, during, and after use. This also applies to the use of urethral sticks so that no germs can penetrate the urethra.

In isolated cases, alprostadil can lower blood pressure and thereby cause dizziness, so driving should be avoided initially.

If the dosage is too high, a permanent erection can occur that lasts four to six hours. If the erection does not go away afterwards, a doctor should be consulted.

The active substance can cause itching or burning in the vagina of the sexual partner, especially when using MUSE. Other rare side effects are listed in the respective package insert of the corresponding medication.


Depending on the dosage form of the drug (tablets, injections, ointment), the interactions can be different.

Alprostadil must not be taken at the same time as the active ingredient papaverine or alpha-receptor blockers, which are used to treat high blood pressure and prostate problems, as these can also trigger an erection.

Taking anticoagulants such as heparin and blood pressure medicines such as beta blockers or nitrates for vasodilatation can also increase the effect of alprostadil. Therefore, concomitant use of these active ingredients should be avoided.