Alprostadil is a synthetic, naturally occurring prostaglandin E1 (PGE1) analogue. It is a potent vasodilator and platelet aggregation inhibitor. In the Indian market, the 500mcg strength is primarily formulated as an injection for intracavernosal use in the diagnosis and treatment of erectile dysfunction (ED) of vasculogenic, neurogenic, or psychogenic origin. It is also used as an intravenous infusion for maintaining patency of the ductus arteriosus in neonates with congenital heart defects awaiting surgery.
Adult: Erectile Dysfunction (Intracavernosal): Initial dose: 2.5 mcg. Titrate upwards in 2.5-5 mcg increments to a minimum effective dose that produces an erection not exceeding 1 hour. Maximum single dose: 60 mcg. Dosing frequency should not exceed once daily and 3 times per week.
Note: INTRACAVERNOSAL: Use a U-100 insulin syringe (0.5 or 1 mL). Administer at the lateral aspect of the proximal third of the penis, alternating sides. Use aseptic technique. Apply pressure to site for 5 minutes. Patient must be trained by a healthcare professional. INTRAVENOUS (Neonates): Administer via a large vein or umbilical artery catheter. Use an infusion pump. Reconstitute as per manufacturer's instructions.
Alprostadil binds to specific prostaglandin E1 receptors on vascular and cavernosal smooth muscle cells. This activates adenylate cyclase, increasing intracellular cyclic adenosine monophosphate (cAMP). Elevated cAMP leads to decreased intracellular calcium, resulting in smooth muscle relaxation (vasodilation). In the penis, this relaxes trabecular smooth muscle and dilates cavernosal and helicine arteries, increasing blood flow, trapping blood, and causing erection. Systemically, it causes vasodilation and inhibits platelet aggregation.
Pregnancy: Category C (US FDA). Not indicated for use in women. No adequate and well-controlled studies. Should not be used during pregnancy unless potential benefit justifies potential risk to the fetus.
Driving: May cause dizziness or syncope. Patients should not drive or operate machinery until they know how the drug affects them, especially after the first few doses.
| Anticoagulants (Warfarin, NOACs) / Antiplatelets (Aspirin, Clopidogrel) | Increased risk of bleeding and hematoma at injection site. | Moderate |
| Antihypertensives | Additive hypotensive effect. | Moderate |
| Other Vasodilators (e.g., Nitrates, PDE5 inhibitors like Sildenafil) | Profound hypotension. CONTRAINDICATED for concomitant use with intracavernosal Alprostadil. | High |
| Monoamine Oxidase Inhibitors (MAOIs) | Potential for exaggerated hypotensive response. | Moderate |
Same composition (Alprostadil (500mcg)), different brands: