Dosing and uses of Cytotec (misoprostol)
Adult dosage forms and strengths
tablet
- 100mcg
- 200mcg
NSAID-Induced Ulcer
Prophylaxis
200 mcg PO q6hr with food; may be decreased to 100 mcg q6hr if higher dose is not tolerated; last dose to be administered at bedtime
Should take therapy for duration of therapy
Pregnancy Termination
See mifepristone (Mifeprex) drug monograph for FDA approved dosage regimen
Stress Ulcer Prophylaxis (Off-label)
100-200 mcg PO q4-6hr
Induction of Labor (Off-label)
25 mcg (1/4 of 100-mcg oral tablet) intravaginally initially, then repeat at intervals not to exceed q3-6hr
Not to be used in patients with previous cesarean delivery or major uterine surgery
Postpartum Hemorrhage (Off-label)
Prophylaxis: 600 mcg PO within 1 minute of delivery
Treatment: 800 mcg PO once; use caution if prophylactic dose already given and adverse effects present or observed
Use only in settings where oxytocin not available
Treatment of Incomplete Abortion (Off-label)
600 mcg buccally once
Intrauterine Fetal Death (Orphan)
Treatment of intrauterine fetal death not accompanied by complete expulsion of products of conception in second and third trimesters of pregnancy
Orphan indication sponsor
- Gynuity Health Projects, LLC; 15 East 26th Street; New York, NY 10010
Dosing Modifications
Renal impairment: Use with caution; peak plasma concentration, half-life, and bioavailability may be increased, but it is not clear whether these increases are of clinical relevance
Pediatric dosage forms and strengths
tablet
- 100mcg
- 200mcg
Fat Absorption in Cystic Fibrosis Patients (Off-label)
<8 years: Safety and efficacy not established
≥8 years: 100 mcg PO q6hr
Geriatric dosage forms and strengths
NSAID-Induced Ulcer
To avoid possibility of diarrhea, dosing may be initiated at 100 mcg q6hr and increased by 100 mcg/day every 3 days until desired dose is achieved
Cytotec (misoprostol) adverse (side) effects
>10%
Diarrhea (14-40%)
Abdominal pain (13-20%)
1-10%
Headache (2%)
Frequency not defined
Anaphylaxis
Anemia
Cardiac dysrhythmia
Chest pain
Flatulence
Gastrointestinal hemorrhage
Hearing loss
Myocardial infarction
Nausea
Rupture of uterus
Thromboembolic disorder
Warnings
Black box warnings
Bacterial infections reported after use
Patients must seek medical attention if excessive bleeding occurs
Administration to pregnant women can cause abortion, premature birth, or birth defects
Uterine rupture has been reported when drug is administered to pregnant women to induce labor or induce abortion beyond 8th week of gestation
Contraindicated in pregnant women to reduce peptic ulcer risk from nonsteroidal anti-inflammatory drugs (NSAIDs)
Warn patients of risk for abortion, and warn them not to give drug to others
Use in women of childbearing potentiaL
- Do not use for reducing risk of NSAID-induced ulcers in women of childbearing potential unless patient is at high risk for complication from gastric ulcers; may be prescribed in the following situations:
- (1) Patient has negative serum pregnancy test result within 2 weeks before initiation of therapy
- (2) Patient is capable of complying with effective contraceptive measures
- (3) Patient has received both oral and written warnings about misoprostol hazards, risk of possible contraception failure, and danger to other women of childbearing potential should drug be taken by mistake
- (4) Patient will begin misoprostol only on day 2 or 3 of next normal menstrual period
Contraindications
Pregnancy when used to reduce risk of NSAID-induced ulcers
Hypersensitivity to misoprostol, prostaglandins, or prostaglandin analogues
Cautions
May cause diarrhea; should not be coadministered with other drugs that cause diarrhea (eg, magnesium-containing antacids)
Adequate contraception is required in women of childbearing age
May cause anaphylactic reaction
May cause chills
Unknown whether drug is safe for use in women with severe anemia
Safety and efficacy in patients with cardiovascular disease, diabetes, renal impairment, or respiratory disease are not established
Use with caution in women >35 years or heavy smokers (these patients were not included in clinical trials)
Off-label use
- For hospital use only if used off label for cervical ripening, induction of labor, or treatment of serious postpartum hemorrhage
- Uterine activity and fetal status should be monitored by trained obstetric personnel in hospital setting
- May be associated with meconium passage, meconium staining of amniotic fluid, and cesarean delivery
- Maternal shock, maternal death, fetal bradycardia, and fetal death have been reported
Pregnancy and lactation
Pregnancy category: X
Lactation: Drug is rapidly metabolized in mother to misoprostol acid, which is biologically active and is excreted in breast milk; although no published reports of adverse effects of misoprostol in breast-feeding infants exist, caution should be exercised when misoprostol is administered to breastfeeding women
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Cytotec (misoprostol)
Mechanism of action
Synthetic prostaglandin E analogue parent drug that is rapidly deesterified to misoprostol acid (active metabolite) and replaces protective prostaglandins consumed with therapies that inhibit prostaglandin synthesis; inhibits gastric acid secretion and protects gastric mucosa
Significantly reduces degree of fat malabsorption in patients with >10% fat malabsorption, possibly by stimulating duodenal bicarbonate production
Absorption
Bioavailability: Unquantified
Onset: 2-3 hr (initial response for acid secretion)
Duration: ≥3 hr (inhibition of acid secretion)
Peak plasma time: Misoprostol acid (active metabolite), 14 min
Distribution
Protein bound: Misoprostol acid (active metabolite), 80-90%
Metabolism
Extensive and rapid 1st-pass metabolism by liver to form misoprostol acid (active metabolite)
Metabolites: Misoprostol acid (principal and active metabolite), dinor and tetranor metabolites of misoprostol acid
Elimination
Half-life: Misoprostol acid (active metabolite), 20-40 min
Dialyzable: No
Excretion: Urine (80%)
