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Misoprostol information from DrugsUpdate  

See Available Brands of Misoprostol in India

P - Contraindicated in pregnancy
L - Contraindicated in lactation

Misoprostol is a drug that is used for the prevention of non-steroidal anti-inflammatory drug (NSAID)-induced gastric ulcers, for early abortion, to treat missed miscarriage, and to induce labor. The last use is controversial in the United States. Misoprostol was invented and marketed by G.D. Searle & Company (now Pfizer) under the trade name Cytotec (often misspelled Cyotec), but other brand-name and generic formulations are now available as well.

Chemically, misoprostol is a synthetic prostaglandin E1 (PGE1) analogue.

Pharmacodynamics

Misoprostol has both antisecretory (inhibiting gastric acid secretion) and (in animals) mucosal protective properties. NSAIDs inhibit prostaglandin synthesis, and a deficiency of prostaglandins within the gastric mucosa may lead to diminishing bicarbonate and mucus secretion and may contribute to the mucosal damage caused by these agents. Misoprostol can increase bicarbonate and mucus production, but in man this has been shown at doses 200 mcg and above that are also antisecretory. It is therefore not possible to tell whether the ability of Misoprostol to reduce the risk of gastric ulcer is the result of its antisecretory effect, its mucosal protective effect, or both.

In vitro studies on canine parietal cells using tritiated Misoprostol acid as the ligand have led to the identification and characterization of specific prostaglandin receptors. Receptor binding is saturable, reversible, and stereospecific. The sites have a high affinity for Misoprostol, for its acid metabolite, and for other E type prostaglandins, but not for F or I prostaglandins and other unrelated compounds, such as histamine or cimetidine. Receptor-site affinity for Misoprostol correlates well with an indirect index of antisecretory activity. It is likely that these specific receptors allow Misoprostol taken with food to be effective topically, despite the lower serum concentrations attained.

Misoprostol produces a moderate decrease in pepsin concentration during basal conditions, but not during histamine stimulation. It has no significant effect on fasting or postprandial gastrin nor on intrinsic factor output.

Pharmacokinetics

Misoprostol, a synthetic prostaglandin E1 analogue, exerts its antisecretory activity by directly acting on specific prostaglandin receptors found on the surface of gastric parietal cells. It exerts its protective effects on the mucosa by replacing the prostaglandins consumed during prostaglandin-inhibiting therapies e.g. NSAIDs.

Absorption
Rapidly absorbed from the GI tract (oral). Peak plasma concentration in 15-30 minutes

Metabolism
Rapidly metabolised to misoprostol acid (active form).

Excretion
Mainly via urine. Elimination half-life: 20-40 minutes

Misoprostol Indications / Misoprostol Uses

Information Not Available

Misoprostol Adverse Reactions / Misoprostol Side Effects

Diarrhoea, abdominal pain, dyspepsia, constipation, flatulence, nausea and vomiting; abnormal vaginal bleeding, cramps, increased uterine contractility, headache.

Precautions

Caution should be employed when administering Misoprostol to patients with pre-existing cardiovascular disease.

Overdosage
Symptoms: Sedation, tremor, convulsions, dyspnoea, abdominal pain, diarrhoea, hypotension, bradycardia. Management: Symptom-directed and supportive

Special Precautions

Conditions where hypotension might precipitate severe complications e.g. cerebrovascular or CV disease. Inflammatory bowel disease. Patients prone to dehydration. Elderly. Renal impairment.

Other Drug Interactions

May increase effects of oxytocin. Increased risk of misoprostol-induced diarrhoea with magnesium-containing antacids.

Other Interactions

Information Not Available

Dosage

Oral
NSAID-associated ulceration
Adult: 800 mcg daily in 2-4 divided doses for at least 4 weeks, up to 8 weeks if needed.
Elderly: Reduce dose if patients are unable to tolerate usual adult dose.
Renal impairment: Reduce dose if patients are unable to tolerate usual adult dose.

Oral
Benign gastric and duodenal ulceration
Adult: 800 mcg daily in 2-4 divided doses for at least 4 weeks, up to 8 weeks if needed.
Elderly: Reduce dose if patients are unable to tolerate usual adult dose.
Renal impairment: Reduce dose if patients are unable to tolerate usual adult dose.

Oral
Prophylaxis of NSAID-induced ulcers
Adult: 200 mcg 2-4 times daily. Patient not tolerating high dose: Reduce dose to 100 mcg 2-4 times daily.
Elderly: Reduce dose if patients are unable to tolerate usual adult dose.
Renal impairment: Reduce dose if patients are unable to tolerate usual adult dose.

Oral
Cervical ripening before surgical termination of pregnancy in the 1st trimester
Adult: 400 mcg as a single dose 3-4 hours before surgery.

Oral
Termination of pregnancy (49 days or less duration)
Adult: 400 mcg as a single dose 36-48 hours after mifepristone.

Food(before/after)

Should be taken with food.

List of Contraindications

Misoprostol and Pregnancy

Contraindicated in pregnancy

Category X: Studies in animals or human beings have demonstrated foetal abnormalities or there is evidence of foetal risk based on human experience or both, and the risk of the use of the drug in pregnant women clearly outweighs any possible benefit. The drug is contraindicated in women who are or may become pregnant.

Misoprostol and Lactation

Contraindicated in lactation

Misoprostol and Children

Safety and efficacy not established in children younger than 18 years of age.

Misoprostol and Geriatic

Reduce dosage if usual dose is not tolerated.

Misoprostol and Other Contraindications

Women of childbearing potential. Pregnancy and lactation.

Storage

Oral
Store at or below 25°C (77°F).

Lab interference

Oral
Store at or below 25°C (77°F).

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