Misoprostol

Brand Names: Cytotec

Drug Class: Prostaglandin E1 analog / Gastric mucosal protectant

Overview

Misoprostol is a synthetic prostaglandin E1 analog used primarily to reduce the risk of NSAID-induced gastric ulcers in high-risk patients. It works by replacing protective prostaglandins depleted by NSAIDs, enhancing gastric mucosal defense. The drug is contraindicated in pregnancy due to its abortifacient properties and potential fetal harm.

Mechanism of Action

Misoprostol is a synthetic prostaglandin E1 analog that replaces prostaglandins depleted by NSAIDs. It exerts a protective effect on the gastric mucosa by inhibiting gastric acid secretion and stimulating bicarbonate and mucus production, enhancing mucosal defense mechanisms.

Indications

  • Reducing the risk of NSAID-induced gastric ulcers in high-risk patients (elderly, those with debilitating diseases, or history of ulcers)
  • Should be taken for the duration of NSAID therapy

Common Doses

  • 100 mcg tablet
  • 200 mcg tablet

Dosage

Recommended adult oral dose is 200 mcg four times daily with food and at bedtime. If not tolerated, reduce to 100 mcg four times daily. Should be taken for the duration of NSAID therapy as prescribed.

Black Box Warning

BOXED WARNING: Not for use in pregnant women to reduce NSAID-induced ulcer risk

Contraindications

  • Pregnancy (due to abortifacient properties and fetal risk)
  • History of allergy to prostaglandins

Side Effects

  • Diarrhea (most common, dose-related, often self-limiting)
  • Abdominal pain
  • Nausea
  • Flatulence
  • Headache
  • Dyspepsia
  • Gynecological disorders (spotting, cramps, menstrual changes)
  • Rare but serious: severe dehydration from diarrhea, uterine bleeding, incomplete abortion, cardiovascular events

Interactions

  • May augment activity of oxytocic agents (avoid concomitant use within 4 hours of oxytocin)
  • No clinically significant interactions with aspirin, diclofenac, or ibuprofen
  • Avoid coadministration with magnesium-containing antacids (may worsen diarrhea)

Counseling Points

  • Take with food and at bedtime to minimize diarrhea
  • Discontinue immediately if pregnancy is suspected or confirmed
  • Report severe diarrhea, abdominal pain, or vaginal bleeding to healthcare provider
  • Use effective contraception during treatment
  • Do not share medication as it has abortifacient properties
  • Complete full course as prescribed with NSAID therapy