What it's for (Indications)
- Prevention of NSAID-induced gastric ulcers.
- For other uses, such as labor induction or medical abortion, misoprostol is used under strict medical supervision following specific instructions from a physician.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | For reducing the risk of NSAID-induced gastric ulcers, the recommended adult oral dose is 200 mcg four times daily, taken with food (with meals and at bedtime). If this dose cannot be tolerated, a dose of 100 mcg can be used. Misoprostol should be taken for the duration of NSAID therapy. For other uses, such as labor induction or medical abortion, dosage should strictly follow specific physician instructions; in some contexts, 4 x 200 mcg tablets (800 mcg total) may be taken at once, with dosage dependent on patient's condition, age, and response. Tablets should be taken by mouth with a glass of water and not crushed, chewed, or dissolved. Vaginal administration may be considered for certain uses (e.g., Breeky tablets), and consultation with a doctor is necessary for such routes. For patients with renal impairment, adjustment of the dosing schedule is not routinely needed, but the dose can be reduced if the 200 mcg dose is not tolerated. |
Safety & Warnings
Common Side Effects
- Common side effects include diarrhea (which can be dose-related, usually self-limiting but rarely profound leading to severe dehydration), abdominal pain, nausea, and headache.
- Other possible side effects include gastrointestinal bleeding, heartburn, dizziness, rise in blood pressure, vomiting, seizures, neck stiffness, and severe allergic reactions (e.
- g.
- , shortness of breath, rashes).
- Uterine rupture has been reported, particularly when used for labor induction.
Serious Warnings
- Black Box Warning: MISOPROSTOL ADMINISTRATION TO WOMEN WHO ARE PREGNANT CAN CAUSE BIRTH DEFECTS, ABORTION, PREMATURE BIRTH OR UTERINE RUPTURE. UTERINE RUPTURE HAS BEEN REPORTED WHEN MISOPROSTOL WAS ADMINISTERED IN PREGNANT WOMEN TO INDUCE LABOR OR TO INDUCE ABORTION. THE RISK OF UTERINE RUPTURE INCREASES WITH ADVANCING GESTATIONAL AGES AND WITH PRIOR UTERINE SURGERY, INCLUDING CESAREAN DELIVERY. MISOPROSTOL SHOULD NOT BE TAKEN BY PREGNANT WOMEN TO REDUCE THE RISK OF ULCERS INDUCED BY NONSTEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDs).
- Patients with a history of heart disease, coronary artery bypass graft, or myocardial infarction should use misoprostol with caution or not at all.
- Use with caution in patients with inflammatory bowel disease or those at risk of dehydration, as profound diarrhea can occur.
- Avoid alcohol consumption as it may increase the risk of stomach irritation.
- Inform your doctor about all existing medical conditions and other medications being taken.
- Older patients should use misoprostol only upon doctor's consultation due to the potential for serious side effects.
- Patients with impaired liver function should consult their doctor before taking this medication.
- Misoprostol is not recommended for use during pregnancy for ulcer prevention due to its uterine contracting properties.
- It is not known whether Misoprostol passes into breast milk; however, due to potential risk, it is generally advised not to use while breastfeeding.
- Store at room temperature, away from direct heat and sunlight.
- Keep out of reach of children and pets.
How it Works (Mechanism of Action)
Misoprostol is a synthetic prostaglandin E1 (PGE1) analogue that exerts its pharmacological effects by binding to specific prostaglandin receptors (primarily EP2 and EP3 subtypes) located on various cell types throughout the body. Its actions are primarily recognized in two main physiological systems: the gastrointestinal tract and the reproductive system. In the gastrointestinal system, misoprostol acts on the parietal cells of the stomach, where it directly inhibits basal and stimulated gastric acid secretion by reducing the activity of the proton pump and decreasing the production of cyclic AMP in response to histamine. Simultaneously, it enhances the endogenous cytoprotective mechanisms of the gastric and duodenal mucosa. This cytoprotective effect involves stimulating the secretion of bicarbonate and mucus, which form a protective barrier against damaging agents like acid and pepsin. Furthermore, misoprostol increases mucosal blood flow, aiding in the maintenance and repair of the gastric lining, thus making it highly effective in preventing and treating non-steroidal anti-inflammatory drug (NSAID)-induced gastric ulcers.
In the female reproductive system, misoprostol induces powerful uterine contractions by binding to myometrial prostaglandin receptors, which subsequently leads to an increase in intracellular calcium concentration within uterine smooth muscle cells. This surge in calcium triggers muscle fiber shortening, resulting in rhythmic and forceful uterine contractions. Concurrently, misoprostol promotes cervical ripening and effacement. This process involves the degradation of collagen fibers within the cervical stroma, an increase in water content, and changes in the extracellular matrix, leading to softening and dilatation of the cervix. These combined actions on uterine contractility and cervical ripening make misoprostol a versatile agent for various obstetric and gynecological applications, including medical termination of pregnancy, induction of labor, cervical preparation prior to surgical procedures, and management of postpartum hemorrhage. The dual nature of its mechanism, encompassing both gastric cytoprotection and uterine stimulation, underpins its broad clinical utility.