Overview
Alprostadil is a synthetic prostaglandin E1 analog used primarily for the treatment of erectile dysfunction (ED) and to maintain patency of the ductus arteriosus in neonates with congenital heart defects. It works by relaxing smooth muscle and dilating blood vessels, increasing blood flow to specific areas.
Mechanism of Action
Alprostadil binds to prostaglandin E1 receptors on smooth muscle cells, activating adenylate cyclase, increasing intracellular cyclic AMP (cAMP), and causing smooth muscle relaxation and vasodilation. In erectile dysfunction, this increases blood flow to the corpus cavernosum, facilitating erection.
Indications
- Erectile dysfunction (ED) of vasculogenic, neurogenic, or psychogenic etiology
- Maintaining patency of the ductus arteriosus in neonates with congenital heart defects pending surgery (e.g., transposition of great arteries, pulmonary atresia)
- Diagnostic aid in erectile dysfunction
Dosage
For ED (intracavernosal injection): Initial dose 1.25-2.5 mcg, titrated up to 60 mcg based on response. For ED (intraurethral pellet): 125-1000 mcg pellet inserted into urethra. For neonatal ductus arteriosus: Initial IV infusion 0.05-0.1 mcg/kg/min, adjusted based on response. Always follow specific product labeling and physician instructions.
Contraindications
- Hypersensitivity to alprostadil or any component
- Conditions predisposing to priapism (e.g., sickle cell anemia, multiple myeloma, leukemia)
- Anatomical penile deformity (e.g., Peyronie's disease, cavernosal fibrosis)
- Penile implants
- Neonates with respiratory distress syndrome
- Use in women or children
Side Effects
- Penile pain (common with injection or urethral administration)
- Priapism
- Penile fibrosis or nodules
- Hypotension
- Headache
- Dizziness
- Injection site reactions (pain, hematoma, ecchymosis)
- Urethral burning (with intraurethral pellet)
- Respiratory depression or apnea (in neonates)
- Fever, sepsis (in neonates)
Interactions
- Anticoagulants (e.g., warfarin, heparin) may increase bleeding risk with injections
- Antihypertensives may potentiate hypotension
- Other erectile dysfunction drugs (e.g., PDE5 inhibitors like sildenafil) increase risk of priapism and hypotension - concurrent use contraindicated
- Vasodilators may enhance hypotensive effects