Drug reference

Misoprostol

Prostaglandin E1 analog (gastroprotective / uterotonic) · Gastric cytoprotective, abortifacient, cervical ripening agent, uterotonic

Also known as Cytotec, Misotac, Misogon, Contrac, Prostodin, Dinoprostone E1 (analogue)

START

For GI indication: ensure woman of childbearing potential has negative pregnancy test and uses effective contraception. Counsel on uterotonic risk. Take with food to reduce GI side effects.

TYPICAL MAX

800mcg/day for ulcer prevention. Higher doses increase diarrhea without proportional GI benefit. For obstetric use: follow WHO/ACOG protocols.

STOP IF

Severe diarrhea (>7 days), dehydration, severe abdominal pain, pregnancy (for GI indication), uterine rupture signs.

WATCH

Diarrhea is most common side effect—usually resolves in 1 week. Take with meals and at bedtime to minimize GI upset. For NSAID ulcer prevention: PPIs (omeprazole) are generally preferred due to better tolerability and QD dosing. Misoprostol remains important where PPIs are unavailable or for cost reasons, and in obstetric applications.

CDSCO approvedHNPPA price-controlledATC A02BB01

Dose laddermg/d

Renal dose adjustmenteGFR mL/min/1.73m²

KDIGO 2024 + manufacturer label

Pharmacokineticsplasma · t hours

ONSET: 6min · Onset ~6 min
PEAK: 12min · Tmax active metabolite ~12-15 min
t½: 30min · t½ 20-40 min
DURATION: 4.5h · 3-6 hours

EXCRETION

Renal as metabolites (~64%)

route + CYP

INTERACTIONS

—

none in our sources

PREGNANCY

CONTRAINDICATED for ulcer prevention in pregnancy (uterotonic effect causes abortion). FOR obstetric indications (abortion, PPH, induction): used specifically for uterotonic effect under medical supervision. Pregnancy category X for GI indication.

FDA category + note

Available in India

51 branded formulations and 7 fixed-dose combinations. Look up specific brands in the Drugs workspace.

Mechanism

Binds to prostaglandin receptors on gastric parietal cells, inhibiting basal and stimulated gastric acid secretion. Also stimulates mucus and bicarbonate secretion, maintains mucosal blood flow, and promotes epithelial regeneration. In uterus: causes contractions via prostaglandin receptor activation.

Indications

Prevention of NSAID-induced gastric ulcers (in patients at high risk)Medical abortion (with mifepristone)Cervical ripening and labor induction (off-label in some countries; approved in others)Postpartum hemorrhage (prevention and treatment—off-label in some regions)Incomplete abortion (off-label)

Dosing

Adult: Ulcer prevention (with NSAIDs): 200mcg PO QID with meals and at bedtime. If not tolerated, 100mcg QID. Medical abortion: 800mcg buccal/vaginal 24-48h after mifepristone 200mg (may repeat once). Labor induction: 25mcg vaginally q3-6h (max 50mcg/dose). PPH: 600-1000mcg sublingual/rectal.
Pediatric: Not established in children for GI indication.
Renal adjustment: No adjustment needed.
Hepatic adjustment: No adjustment needed (rapidly metabolized).
Geriatric: No specific adjustment; increased GI side effects at higher doses.
Max dose: 800mcg/day (ulcer prevention); 1600mcg (medical abortion single dose)

Pharmacokinetics

Onset

Gastric acid suppression within 30 minutes; uterotonic effect within minutes

Peak effect

Tmax 12-15 minutes (active metabolite misoprostolic acid); acid suppression peaks at 60-90 minutes

Duration

3-6 hours (gastric acid suppression)

Half-life

~20-40 minutes (misoprostol); ~90 minutes (misoprostolic acid)

Bioavailability

~88% (extensive first-pass effect; active metabolite is systemic)

Protein binding

~85% (misoprostolic acid)

Metabolism

Rapid de-esterification in gut wall to active misoprostolic acid; then hepatic beta-oxidation to inactive metabolites

Excretion

~64% renal (inactive metabolites); ~15% fecal

Contraindications

Pregnancy (for ulcer prevention indication—uterotonic effect can cause miscarriage)
Hypersensitivity to prostaglandins
Active inflammatory bowel disease (relative)

Side effects

Common

Diarrhea (most common—dose-related, often self-limiting)Abdominal pain / crampingNauseaFlatulenceDyspepsiaHeadacheUterine bleeding / cramping (women of childbearing potential)

Serious