Short answer: Alprostadil has a half-life of minutes (about 9 to 11 minutes in healthy volunteers). Levels peak 2 to 5 minutes after an injection into the penis after a dose. People vary, so treat these as estimates.
Alprostadil is prostaglandin E1, a compound the body makes that relaxes smooth muscle and widens blood vessels. Injected into the side of the penis, it fills the erectile tissue with blood. It is sold as Caverject (Pfizer) and Edex (Endo) for erectile dysfunction.
Also known as: Caverject, Edex, prostaglandin E1, PGE1.
Caverject comes as 20 mcg and 40 mcg single-dose powder vials, mixed with 1 mL of bacteriostatic water. Edex comes as 10, 20 and 40 mcg single-dose, two-chamber cartridges used with a reusable injection device, which mixes the saline into the powder. Both are injected with a fine needle into the side of the penis, alternating sides.
The Caverject label approves alprostadil to treat erectile dysfunction and to help diagnose it; the Edex label approves it for erectile dysfunction from nerve, blood vessel, psychological or mixed causes. Both labels find the dose in the prescriber's office, starting at 2.5 mcg (1.25 mcg for nerve or spinal cord injury) and stepping up until an erection suitable for sex lasts no more than 1 hour. At home it is used no more than 3 times a week, at least 24 hours apart. Caverject doses above 60 mcg are not recommended; the Edex range is 1 to 40 mcg.
Neither label has a boxed warning. An erection lasting over 4 hours needs immediate medical help, because untreated priapism can cause lasting damage. Other warnings cover penile scarring and curvature (the penis is examined regularly), low blood pressure, and bleeding with blood thinners. It is not used with sickle cell disease or trait, multiple myeloma, leukemia, Peyronie's disease or a penile implant. Penile pain was 37% in Caverject studies. Full numbers are on the Caverject side effects, Caverject dosing schedule, Edex side effects and Edex dosing schedule pages, Caverject vs Edex compares the two, and storage is on the Caverject and Edex pages.
The Edex label says that after a 20 mcg injection into the penis, blood levels of alprostadil peaked within 2 to 5 minutes and were back to the body's own level within 2 hours. It gives a terminal half-life of about 9 to 11 minutes in healthy volunteers. The Caverject label says about 80% of alprostadil given into a vein is broken down in one pass through the lungs.
Numbers shown are taken from the source above. Half-life varies from person to person.
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