Alprostadil is a synthetic form of prostaglandin E1, a naturally occurring substance in the body that plays a critical role in vasodilation and penile erection. As a direct-acting vasodilator, it is a cornerstone in the medical management of erectile dysfunction (ED), offering a targeted, non-systemic approach that bypasses many limitations of oral therapies. This medication is available in multiple formulations—intracavernosal injection, intraurethral pellet, and topical cream—allowing for tailored treatment based on patient preference, etiology of ED, and clinical suitability. Its mechanism of action involves relaxing smooth muscle tissue in the corpora cavernosa, facilitating increased blood flow and enabling a reliable, on-demand erection. Alprostadil represents a well-established, efficacious option for patients who have contraindications to or have failed phosphodiesterase type 5 inhibitors.

Features

• Synthetic prostaglandin E1 analog with high purity and consistent pharmacological activity
• Available in multiple administration routes: intracavernosal injection (e.g., Caverject, Edex), intraurethral suppository (MUSE), and topical formulation (e.g., Vitaros)
• Rapid onset of action, typically within 5–15 minutes for injection and intraurethral routes
• Short half-life (approximately 5–10 minutes in plasma), minimizing systemic exposure
• Does not depend on nitric oxide pathway, making it effective in neurogenic, vasculogenic, and psychogenic ED
• Prefilled syringes and adjustable dosing pens available for accurate, user-friendly administration

Benefits

• Provides a reliable, predictable erectile response, independent of sexual stimulation
• Effective in a broad range of ED etiologies, including post-prostatectomy, diabetic, and hypertensive patients
• Avoids first-pass metabolism, reducing potential hepatic interactions
• Enables titration to the lowest effective dose, minimizing side effects while maintaining efficacy
• May be used in combination therapies (e.g., with papaverine or phentolamine) for synergistic effect in refractory cases
• Supports psychological confidence and relationship satisfaction through successful treatment outcomes

Common use

Alprostadil is primarily indicated for the diagnosis and treatment of erectile dysfunction. It is especially valuable in cases where oral phosphodiesterase type 5 inhibitors (e.g., sildenafil, tadalafil) are contraindicated, ineffective, or poorly tolerated. Common clinical scenarios include post-radical prostatectomy patients with neurogenic ED, individuals with severe vascular disease, and those taking concomitant medications that interact with PDE5 inhibitors. It is also used in diagnostic settings to assess vascular integrity in erectile function. Off-label, alprostadil is utilized in neonates for maintaining patency of the ductus arteriosus in certain congenital heart conditions, though this application is distinct from its use in adult medicine.

Dosage and direction

Dosing is highly individualized and depends on the formulation:

• Intracavernosal injection: Start with 2.5 mcg; titrate upward in 2.5–5 mcg increments to achieve an erection lasting no longer than 1 hour. Maximum dose is typically 60 mcg. Administer into the lateral aspect of the penile shaft, alternating sides.
• Intraurethral pellet (MUSE): Initial dose is 125 mcg; may increase to 250 mcg, 500 mcg, or 1000 mcg as needed. Insert applicator into urethra and depress button to release pellet.
• Topical cream (Vitaros): Apply one actuation (300 mcg alprostadil) to the meatus and urethral opening; gently massage for 30 seconds.

Administration should not exceed once per 24 hours. Proper training in injection technique or applicator use is essential to minimize complications. Patients should be advised to discard needles and supplies appropriately.

Precautions

• Priapism (erection lasting >4 hours) is a medical emergency; patients must seek immediate care to prevent permanent tissue damage.
• Use with caution in patients with penile anatomical deformities (e.g., Peyronie’s disease), risk of fibrosis, or history of priapism.
• Monitor for hypotension, especially in volume-depleted or cardiovascularly compromised individuals.
• Avoid use in conditions predisposing to bleeding (e.g., coagulopathies, thrombocytopenia).
• Urethral bleeding may occur with intraurethral formulation; advise patients accordingly.
• Storage conditions vary by product; some require refrigeration.

Contraindications

• Hypersensitivity to alprostadil or any component of the formulation.
• Conditions that increase risk of priapism (e.g., sickle cell anemia, multiple myeloma, leukemia).
• Anatomical penile deformities that may contraindicate injection.
• Use in women, children, or neonates (except for specific cardiac indications under specialist care).
• Concurrent use with other erectile agents unless under strict medical supervision.

Possible side effect

• Penile pain (up to 30–40% of users, often dose-dependent)
• Prolonged erection or priapism (1–5%)
• Penile fibrosis or nodules (with chronic injection use)
• Urethral burning or bleeding (intraurethral formulation)
• Hypotension, dizziness, or syncope
• Local hematoma or ecchymosis at injection site
• Headache
• Upper respiratory tract infection (rare)

Drug interaction

• Antihypertensives, alpha-blockers, or nitrates: may potentiate hypotensive effects.
• Anticoagulants (e.g., warfarin, apixaban): increased risk of bleeding or hematoma with injection.
• Other erectile dysfunction agents: increased risk of priapism or severe hypotension.
• Drugs affecting prostaglandin metabolism (e.g., NSAIDs) may theoretically alter efficacy, though clinical significance is unclear.

Missed dose

Alprostadil is used on an as-needed basis; there is no scheduled dosing regimen. If a dose is missed or not administered correctly, it may be taken when remembered, but not more than once in a 24-hour period. Do not double the dose.

Overdose

Overdose may manifest as prolonged or painful erection, severe hypotension, dizziness, or syncope. Priapism requires urgent urological intervention—typically corporal aspiration and irrigation with sympathomimetic agents (e.g., phenylephrine). Hypotension should be managed with supportive care, including Trendelenburg positioning and IV fluids if necessary. There is no specific antidote.

Storage

• Refrigerate at 2–8°C (36–46°F) unless otherwise specified; some formulations are stable at room temperature for limited periods.
• Protect from light.
• Do not freeze.
• Keep out of reach of children and pets.
• Discard unused medication after expiration date or if discoloration or particulates are observed.

Disclaimer

This information is intended for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting, changing, or stopping any medication. Individual responses to alprostadil may vary. Proper diagnosis and supervision are essential to ensure safe and effective use.

Reviews

“As a urologist with over 20 years of experience, I find alprostadil invaluable for patients who fail oral therapy. The injection form, in particular, offers precision and reliability.” — Dr. Evan R., MD

“After my prostate surgery, sildenafil didn’t work. My doctor recommended alprostadil injections. The learning curve was steep, but the results are consistent and have restored my confidence.” — Patient, 58

“The intraurethral system is less invasive than injections and still effective for me. Some discomfort initially, but it’s manageable.” — Patient, 62

“As a cardiologist, I appreciate that alprostadil doesn’t interact with nitrates—making it a safer choice for some of my patients with heart disease.” — Dr. Lisa T., MD

“Topical cream is a promising option for those averse to needles. Efficacy is good, though not as potent as injections in severe cases.” — Clinical Pharmacist