Alprostadil (Prostaglandin E1)

FDA-approved context Sexual Wellness 3 sources

Alprostadil is a synthetic form of prostaglandin E1 (PGE1), a naturally occurring vasodilator. It is widely researched and utilized for its ability to relax smooth muscle and expand blood vessels, making it a primary treatment for erectile dysfunction and a critical intervention for maintaining ductus arteriosus patency in neonates with specific heart conditions.

01Dosing reference

Amount

1.25 to 20 mcg (ED injection); 125 to 1000 mcg (urethral suppository)

Frequency

As needed, typically no more than 3 times per week (ED)

Cycle

Used on demand; not cycled in the traditional sense

Reference figures, not a recommendationThese values reflect amounts described in the literature and vendor documentation this database indexes. Use the reconstitution calculator to convert them into syringe units.

02Mechanism of action

Receptor Binding

Alprostadil binds to specific prostaglandin receptors (EP receptors) on the surface of smooth muscle cells.

cAMP Elevation

Binding activates adenylate cyclase, leading to an increase in intracellular cyclic adenosine monophosphate (cAMP).

Smooth Muscle Relaxation

Elevated cAMP lowers intracellular calcium levels, causing smooth muscle relaxation and subsequent vasodilation, increasing blood flow to specific areas like the corpus cavernosum.

03Human evidence

Effective in treating erectile dysfunction (ED) of various etiologies.

Extensive clinical trials have demonstrated efficacy via intracavernosal injection or intraurethral application, even in patients non-responsive to oral PDE5 inhibitors.

Maintains patency of the ductus arteriosus in neonates.

Used as a life-saving continuous intravenous infusion in newborns with ductal-dependent congenital heart defects until surgery can be performed.

04Preclinical evidence

Demonstrates potent vasodilatory and anti-platelet aggregation effects.

In vitro and animal models show PGE1 inhibits platelet aggregation and stimulates vasodilation across various vascular beds.

Promotes angiogenesis and improves microcirculation.

Animal models of ischemia indicate that PGE1 can enhance blood flow and support tissue survival in compromised environments.

05What is known vs. unknown

Reasonably established

Acts as a potent vasodilator by relaxing vascular smooth muscle.
FDA-approved for the treatment of erectile dysfunction (ED) and for maintaining ductus arteriosus patency in neonates.
Can be administered via intracavernosal injection, intraurethral suppository, or intravenous infusion depending on the indication.
Inhibits platelet aggregation, contributing to improved microcirculation.

Unknowns & limits

Long-term effects of repeated intracavernosal injections on penile tissue architecture (e.g., fibrosis risk) require careful monitoring.
Optimal dosing protocols for emerging off-label uses in peripheral arterial disease remain under investigation.

06Safety & regulatory context

Regulatory statusAlprostadil is an FDA-approved medication with a well-established safety profile when used as directed. Common side effects for ED treatment include penile pain, urethral burning, and a risk of priapism (prolonged erection) or penile fibrosis with injection. For neonatal use, side effects can include apnea, fever, and hypotension. It is contraindicated in men with conditions predisposing them to priapism (such as sickle cell anemia or leukemia) and in neonates with respiratory distress syndrome. Regulatory status is fully approved for specific medical indications.

07Compared with Sildenafil (Viagra)

Alprostadil (Prostaglandin E1) vs. Sildenafil (Viagra)

Key difference

Alprostadil directly increases cAMP to cause vasodilation and can induce an erection without sexual stimulation, whereas Sildenafil inhibits PDE5 to increase cGMP and requires sexual arousal to be effective.

When researchers discuss each

Sildenafil is discussed as a first-line, systemic oral treatment for ED, while Alprostadil is often discussed as a localized, second-line therapy for patients who fail or cannot tolerate oral medications.

08Glossary

Prostaglandin E1 (PGE1)

A naturally occurring lipid compound that acts as a vasodilator and inhibits platelet aggregation.

Corpus Cavernosum

The sponge-like regions of erectile tissue in the penis that fill with blood during an erection.

Ductus Arteriosus

A blood vessel in a developing fetus connecting the pulmonary artery to the descending aorta, which normally closes soon after birth.

Priapism

A prolonged and often painful erection lasting more than four hours, requiring immediate medical attention.

09Knowledge check

Q1What is the primary intracellular mechanism by which Alprostadil induces smooth muscle relaxation?

Q2Which of the following is a critical FDA-approved indication for Alprostadil in neonates?

Q3Which statement best reflects a documented research limitation about Alprostadil from the supplied dossier?

Q4When comparing Alprostadil and Sildenafil for erectile dysfunction, which contextual statement is supported by the dossier?

Q5Which safety or regulatory statement about Alprostadil is supported by the dossier?

10Sources

More in Sexual Wellness

See all

PT-141 (Bremelanotide)

Sexual Wellness

FDA-approved context

PT-141, also known as bremelanotide, is a synthetic peptide analog of alpha-melanocyte-stimulating hormone (α-MSH). It acts as a non-selective agonist of the melanocortin receptors, primarily MC4R, and is FDA-approved for the treatment of generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. Research shows it can also induce erections in men, working through the central nervous system rather than the vascular system.

1.75 mg (FDA approved dose) or 1-2 mg for research

LIB-01 (Volufralin)

Sexual Wellness

Early human

LIB-01 (Volufralin) is a novel, first-in-class oral drug candidate being developed for the treatment of erectile dysfunction (ED) and premature ejaculation. It works by enhancing melanocortin type-4 receptor (MC4R) signaling in the central nervous system, demonstrating a unique long-lasting effect that can improve erectile function for up to eight weeks after a short dosing period.

10-50 mg (in clinical trials)

Research and educational use onlyNothing on this site is medical advice, a prescription, or a recommendation for human use. Compounds documented here are research chemicals. Consult a qualified clinician before making any health decision.