BLACK BOX WARNING
- contraindicated in pregnant women for GI indications due to abortifacient properties; women of childbearing potential must use effective contraception
misoprostol
Brand: Cytotec
⚠ BBW Prototype Drug
Drug Class: prostaglandin E1 analog
Drug Family: GI agent
Subclass: synthetic prostaglandin (GI and obstetric)
Organ Systems: gastrointestinalreproductive
Mechanism of Action
Binds to prostaglandin EP receptors on gastric parietal cells to inhibit acid secretion and on surface epithelial cells to stimulate mucus and bicarbonate secretion, enhancing mucosal defense. In the uterus, EP2/EP3 receptor activation induces myometrial contractions and cervical ripening.
EP1, EP3 prostaglandin receptors (gastric)EP2, EP3 receptors (uterine)
Indications
- prevention of NSAID-induced gastric ulcers
- cervical ripening and labor induction
- postpartum hemorrhage
- medication abortion (with mifepristone)
- missed or incomplete miscarriage management
Contraindications
- pregnancy (GI indication only — causes uterine contractions)
- allergy to prostaglandins
Adverse Effects
Common
- diarrhea
- abdominal cramping
- nausea
- flatulence
Serious
- uterine hyperstimulation (obstetric use)
- uterine rupture (prior uterine surgery)
- anaphylaxis
Pharmacokinetics (ADME)
| Absorption | rapidly and extensively absorbed orally; sublingual and vaginal routes also effective |
| Distribution | protein binding ~85% |
| Metabolism | rapid de-esterification to active misoprostol acid; no CYP450 involvement |
| Excretion | renal (primarily as metabolites) |
| Half-life | 20–40 minutes |
| Onset | 30 minutes (oral) |
| Peak | 12–15 minutes (oral) |
| Duration | 3–6 hours |
| Protein Binding | 85% |
| Vd | moderate |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| oxytocin | additive uterotonic effect; risk of uterine hyperstimulation | major |
| magnesium antacids | may potentiate diarrhea | minor |
Nursing Considerations
- For GI prophylaxis: confirm patient is not pregnant before initiating; provide contraception counseling.
- For obstetric use: perform continuous fetal heart rate monitoring; misoprostol must not be given within 4 hours of oxytocin due to hyperstimulation risk.
- Store at room temperature away from heat and moisture.
- Educate patients using misoprostol for NSAID prophylaxis that diarrhea (most common side effect) is dose-related and usually resolves; taking with food may reduce GI side effects.
Clinical Pearls
- The only FDA-approved agent for prevention of NSAID-induced gastric ulcers, though PPIs are now more widely used due to better tolerability.
- Sublingual misoprostol achieves faster uterine response than oral administration but with higher rates of GI side effects.
Safety Profile
Pregnancy contraindicated
Lactation use-with-caution
Renal Adjustment Not required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.