Alprostadil (Prostaglandin E1)
Sexual Well-Being
In plain English
Alprostadil is a well-studied medicine that produces an erection by relaxing and widening the blood vessels in the penis. It is FDA-approved as a penile injection and urethral pellet, and it is also a component of compounded Tri-Mix. It works even without sexual stimulation and is used when oral pills are not enough. The main risks are penile pain and prolonged erection.
The science
Alprostadil is synthetic prostaglandin E1 that activates prostaglandin receptors to raise intracellular cAMP, relaxing cavernosal and arterial smooth muscle and producing erection independent of nitric-oxide/PDE5 signaling. A landmark multicenter study (Linet 1996) established the efficacy and safety of intracavernosal alprostadil, with sexual activity possible after ~94% of injections; penile pain (~11% of injections), priapism (~1%), and fibrotic changes (~2%) were the main issues. FDA-approved single-agent alprostadil products exist (intracavernosal injection and intraurethral suppository); combination Tri-Mix (adding papaverine and phentolamine) is compounded and off-label but allows lower alprostadil doses to reduce pain. It is a first-line intracavernosal option in the AUA guideline for men who cannot use or fail oral PDE5 inhibitors; priapism counseling and dose titration are essential.
References
- Linet & Ogrinc, N Engl J Med 1996 (intracavernosal alprostadil, Alprostadil Study Group)
- Burnett et al., J Urol 2018 (AUA Erectile Dysfunction Guideline)