Generic Name: misoprostol

Cytotec is a prostaglandin. Prostaglandins are hormones that are involved in inflammation and pain.

Cytotec is used to decrease the risk of stomach ulcers in certain patients who take nonsteroidal anti-inflammatory drugs (NSAIDs). Cytotec is also used to treat postpartum bleeding or failure of the uterus to contract after childbirth.

Cytotec may also be used for purposes not listed in this medication guide.

Cytotec (misoprostol) is a prostaglandin E1 analog used to prevent gastric ulcers in patients treated with nonsteroidal anti-inflammatory drugs (NSAIDs). Cytotec is also sometimes used to induce labor (to help start the birth process in a pregnant woman). Cytotec should not be used for either purpose without first talking to your doctor.

Pharmacokinetics

Absorption:

After oral administration, misoprostol is rapidly absorbed. Absolute bioavailability has not been determined due to the lack of a suitable assay. Bioavailability is estimated to be about 80%.

Distribution:

Misoprostol acid is distributed throughout the body and crosses the placenta. Mean steady-state plasma concentrations are approximately 3 ng/mL following single and multiple 200 mcg oral doses in healthy women. Misoprostol is widely bound to plasma proteins (99%).

Metabolism:

Misoprostol acid is metabolized in the liver and intestine by oxidative N-demethylation, reduction of the carbonyl group, and O-dealkylation to yield misoprostol diols and other metabolites.

Elimination:

Following oral administration, mean plasma clearance is approximately 0.6 L/hr/kg. Urinary excretion of the metabolites represents the major route of elimination and accounts for about 65% of the dose. fecal excretion accounts for the remaining 35%. The mean terminal half-life is 20 hours following single and multiple oral doses in healthy women.

Drug interactions

Concomitant use of NSAIDs and misoprostol increases the risk of gastrointestinal side effects. The concomitant use of other drugs that affect gastric acid secretion may alter the response to misoprostol.

Cytochrome P450 inducers:

The concomitant use of CYP3A4 inducers (e.g., barbiturates, carbamazepine, efavirenz, griseofulvin, nevirapine, phenytoin, rifampin) with misoprostol may decrease plasma concentrations of misoprostol acid and potentially reduce its efficacy. Monitor for decreased efficacy of misoprostol during co-administration with CYP3A4 inducers and adjust misoprostol dose as needed.

Cytochrome P450 inhibitors:

The concomitant use of CYP3A4 inhibitors (e.g., azole antifungals, clarithromycin, erythromycin, fluconazole, HIV protease inhibitors, ketoconazole, macrolide antibiotics) with misoprostol may increase plasma concentrations of misoprostol acid and potentially increase the risk of gastrointestinal side effects. Monitor for increased gastrointestinal side effects during co-administration with CYP3A4 inhibitors and adjust misoprostol dose as needed.

H2-receptor antagonists:

The concomitant use of H2-receptor antagonists (e.g., cimetidine, famotidine, nizatidine, ranitidine) with misoprostol may decrease plasma concentrations of misoprostol acid and potentially reduce its efficacy. Monitor for decreased efficacy of misoprostol during co-administration with H2-receptor antagonists and adjust misoprostol dose as needed.

Proton pump inhibitors:

The concomitant use of proton pump inhibitors (e.g., omeprazole, lansoprazole) with misoprostol may decrease plasma concentrations of misoprostol acid and potentially reduce its efficacy. Monitor for decreased efficacy of misoprostol during co-administration with proton pump inhibitors and adjust misoprostol dose as needed.

Special populations

Hepatic impairment:

Use caution in patients with mild to moderate hepatic impairment. Avoid use in patients with severe hepatic impairment.

Renal impairment:

Use caution in patients with mild to moderate renal impairment. Avoid use in patients with severe renal impairment.

Side effects

The most common side effects (>3%) associated with the use of misoprostol are diarrhea, abdominal pain, flatulence, and nausea. Other reported side effects include anorexia, dyspepsia, vomiting, headache, dizziness, fatigue/weakness, fever, and chills.

Dosage and Administration

The recommended dosage of Cytotec for reduction of the risk of NSAID-induced gastric ulcers in patients at high risk is 200 mcg four times daily with food. If a patient cannot tolerate misoprostol four times daily, a dose of 200 mcg three times daily should be used. If a patient cannot tolerate misoprostol three times daily, a dose of 200 mcg twice daily should be used.

If signs and symptoms suggestive of a duodenal ulcer are present in addition to gastric ulcer, the total daily dose should not exceed 800 mcg.

For the prevention of NSAID-induced gastric ulcers in patients at low risk, the recommended dosage is 200 mcg twice daily with food.

The recommended dosage of Cytotec for the treatment of active duodenal ulcer is 400 mcg four times daily with food. If a patient cannot tolerate misoprostol four times daily, a dose of 400 mcg three times daily should be used. If a patient cannot tolerate misoprostol three times daily, a dose of 400 mcg twice daily should be used.

For the prevention of NSAID-induced duodenal ulcers, the recommended dosage is 200 mcg four times daily with food. If a patient cannot tolerate misoprostol four times daily, a dose of 200 mcg three times daily should be used.

For the treatment of active gastric ulcer, the recommended dosage is 800 mcg four times daily with food. If a patient cannot tolerate misoprostol four times daily, a dose of 800 mcg three times daily should be used. If a patient cannot tolerate misoprostol three times daily, a dose of 800 mcg twice daily should be used.

For the prevention of NSAID-induced gastric ulcers in patients at high risk, the recommended dosage is 400 mcg four times daily with food. If a patient cannot tolerate misoprostol four times daily, a dose of 400 mcg three times daily should be used.

Overdose

There is no specific antidote for Cytotec overdose. Treatment should be symptomatic and supportive. Consider gastric decontamination with activated charcoal (60 to 100 g in adults, 1 to 2 g/kg in children) if the patient presents within 1 hour of ingestion and there is no contraindication to its use.

Storage

Tablets should be stored at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F). Protect from light and moisture.