Prostaglandin E1 (Alprostadil)

What it is and how it works

Alprostadil is prostaglandin E1, which relaxes vascular and trabecular smooth muscle by increasing intracellular cyclic AMP, causing vasodilation and maintaining patency of the ductus arteriosus. Vaginal PGE1-type products (e.g. misoprostol, a synthetic PGE1 analogue) act on the cervix and myometrium to cause cervical ripening and uterine contractions.

Indications

Intravenous infusion: temporary maintenance of ductus arteriosus patency in neonates with duct-dependent congenital heart disease, and in some countries peripheral arterial occlusive disease. Intracavernosal injection and urethral stick: erectile dysfunction. Vaginal forms: cervical ripening and induction of labour, according to product licence.

Dosage and administration (summary)

Dosing depends on the indication and product and is individualised by the specialist (e.g. neonatal infusion titrated in nanograms/kg/minute; intracavernosal dose titrated in the clinic).

Contraindications

Neonates: respiratory distress syndrome. Erectile dysfunction products: conditions predisposing to priapism (sickle cell disease, multiple myeloma, leukaemia), penile deformity or implants, and men for whom sexual activity is inadvisable. Vaginal labour induction products: previous uterine surgery or caesarean section (product-dependent), fetal distress, malpresentation and when oxytocic drugs are contraindicated.

Warnings and precautions

In neonates, apnoea is common, especially in those under 2 kg, so ventilatory support must be available. Intracavernosal or urethral use may cause penile pain and priapism (erection lasting over 4 hours requires urgent treatment). Vaginal products may cause uterine hyperstimulation and require fetal and uterine monitoring.

Pregnancy

Erectile dysfunction products are not intended for women; vaginal products are used only for the licensed obstetric indications under specialist supervision.

Storage and supply

Alprostadil injection and urethral sticks are usually stored refrigerated (2–8 °C) unless the product states otherwise; vaginal products according to the manufacturer, often frozen or refrigerated for dinoprostone and below 25 °C for misoprostol.

Source: reference summary prepared from the EU SmPC/EPAR, BNF and WHO Model Formulary. The approved product information in Iran governs.