Prostaglandins in pregnancy

A 23-year-old severely asthmatic primigravida suffers a major post-partum haemorrhage

due to uterine atony following a vaginal delivery. As well as appropriate therapy

of major haemorrhage she receives syntometrine intramuscularly, syntocinon intravenously

as a bolus and then by infusion. Which one of the following would be the

MOST SUITABLE agent for further pharmacological management of her condition?

a) Carboprost

b) Mifepristone

c) Misoprostol

d) Alprostadil

e) Dinoprostone

Answer: c

Explanation

All of the options are synthetic prostaglandin analogues except mifepristone, which is a

competitive antagonist at the progesterone receptor (it is used in the induction of

medical abortion and should be avoided in asthmatics). Carboprost (Hemabate®) is

prostaglandin F2α and although is a suitable treatment for post-partum haemorrhage

as an intramuscular injection, it should be avoided in severe asthmatics because of its

side effect of bronchospasm. Dinoprostone (prostaglandin E2 – Prostin E2®) is used as a

vaginal gel or pessary in the process of induction of labour. It should also be used with

caution in asthmatics. Misoprostol (Cytotec®) and alprostadil (Prostin VR®) are both

analogues of prostaglandin E1 and do not carry the same cautions for treatment of

asthmatics. Alprostadil is used on the paediatric intensive care unit for maintaining

patency of the ductus arteriosus in neonates with a duct-dependent circulation.

Misoprostol is encountered in gastroenterology for prevention of peptic ulcers, but is

also used in obstetrics orally, sublingually or often rectally as a second- or third-line

agent in post-partum haemorrhage.