PROSTAGLANDINS

• First isolated from semen and thought to be produced by the prostate gland
• Synthesized from fatty acid arachidonic acid in a wide range of tissues
• Conversion of arachidonic acid to prostaglandin endoperoxide by the enzyme cyclo-oxygenase is inhibited by aspirin and NSAIDs
• Specific cyclo-oxygenase 2 (COX-2) inhibitors are less likely to cause GI side-effects (meloxicam, sulindac)
• Metabolised by the liver and tissues and excreted by the kidney

Clinical use

• Dinoprostone (PGE2) is used for induction of labour (Prostin®, Propess®). It is active orally (less active than following vaginal administration) but side-effects are more frequent
• Dinoprost (PGF2-alpha) - used for pregnancy termination. Similar side-effects to dinoprostone but may be more severe
• Gemeprost (PGE1) - used for cervical preparation prior to surgical evacuation of the uterus and for medical termination of pregnancy. Side-effects similar to PGE2
• Carboprost - administered by deep intramuscular or intra-myometrial injection to treat severe post-partum haemorrhage

Side –effects

• Nausea & vomiting
• Diarrhoea (increased peristalsis)
• Fever
• Hypertension
• Bronchospasm
• Uterine hypertonus or hyperstimulation
• Fetal distress
• Placental abruption
• Amniotic fluid embolism.

Misoprostol

• Synthetic analogue of PGE1 - inhibits gastric acid secretion and is used in the treatment of gastric ulcers.
• Unlicensed use for cervical preparation prior to surgical evacuation of the uterus, medical termination of pregnancy and induction of labour.

Side-effects

• Diarrhoea
• Nausea, vomiting & abdominal pain
• Vaginal bleeding including menorrhagia, inter-menstrual and post-menopausal bleeding