Misoprostol is a synthetic prostaglandin medication that is used to start labor, prevent and treat stomach ulcers, cause abortion and stop postpartum bleeding caused by poor uterus contractions. It was developed in 1973 and is on the List of Essential Medicines of the World Health Organization. It is sold under the brand name Cytotec.
Misoprostol is used by itself and can also be taken with methotrexate and mifepristone for abortions. The effectiveness of abortion by itself is around 66% to 90%. It is taken orally, dissolved in the mouth, or placed in the vagina for abortion and labor induction. It can also be used rectally for postpartum bleeding. When used for the prevention of gastric ulcers, it is consumed orally by individuals taking NSAIDs (Nonsteroidal anti-inﬂammatory drugs).
The Misoprostol indications include reduction of gastric ulcers caused by NSAID but not duodenal ulcers in patients at high risk. It can also be formulated in combination with diclofenac for the treatment of symptoms of rheumatic arthritis or osteoarthritis in patients at risk of developing gastric ulcers.
Misoprostol is most commonly used for the management of miscarriages, for the prevention of postpartum hemorrhage and it can be used by itself or in combination with mifepristone for ﬁrst-trimester abortions.
Mechanism of Action
Misoprostol has gastric mucosal and antisecretory protective effects since it acts as a synthetic replacement for Prostaglandin E1. By suppressing the activation of histamine-sensitive adenylate cyclase, PGE1 inhibits hydrochloric acid through a direct action on gastric parietal cells. It improves blood ﬂow to the mucosa, thereby increasing the oxygen and nutrient supply to it and enhancing epithelialization.
The Misoprostol mechanism of action is such that it binds to myometrial cells causing strong contractions and ultimately resulting in the expulsion of tissue. This medication also causes cervical ripening following the softening and dilation of the cervix. Misoprostol stimulates and binds to the Prostaglandin EP2, EP3, and EP4 receptors but not Prostaglandin EP1 receptor and thus is expected to have a restricted range of potentially toxic physiological effects than Prostaglandin E2 which activates all four receptors.
It is recommended that medical treatment for missed abortion with misoprostol should not be considered for people with the following contraindications:
- Use of non-steroidal drugs
- Suspected ectopic pregnancy
- Signs of pelvic infections
- Known allergy to misoprostol
- Unstable hemodynamics
- Previous cesarean section
- Mitral stenosis
- Bronchial asthma
Precautions should be taken for patients with anemia or a history of bleeding disorder.