Misoprostol
Synthetic prostaglandin E1 analog
Also known as: Cytotec · Arthotec · Arthrotec · Artotec · Artrenac Pro · Condrotec · Corrigast · Cyprostol · Cytolog · Diclotec · Glefos · Menpros · Misodex · Misofenac · Napratec · Normulen · Oxaprost · Symbol · SC-29333 · Misoprostolum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Structured calculator evidencePrevention of aspirin-induced gastric injury (extra-label)
- q8-12h
NA
Governing clinical context (4)
- ■ Give this medicine with food if stomach upset occurs or to prevent stomach upset.
- ■ Common side effects include diarrhea, abdominal/stomach pain, vomiting, and flatulence (ie, gas). These effects may only last a few days, and giving the drug with food may help, but if any of these effects are severe, get worse, or continue to be a problem, contact your veterinarian.
- ■ This medicine is considered to be a hazardous drug because it may affect the reproductive ability of males or females actively trying to conceive, women who are pregnant or may become pregnant, as it can cause miscarriage, and women who are breastfeeding. It is recommended that you wear gloves when administering this medicine to your animal and wash your hands thoroughly afterwards. If you have questions about this medicine’s hazards, please speak with your veterinarian or pharmacist.
- Misoprostol tablets should be stored in well-closed containers at room temperature of 25°C (77°F) or less.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Misoprostol is a synthetic prostaglandin E1 (PGE1) analog primarily utilized in veterinary medicine to prevent and treat gastric ulceration, particularly those induced by nonsteroidal anti-inflammatory drugs (NSAIDs).
NSAIDs inhibit cyclooxygenase (COX) enzymes, which depletes the protective prostaglandins in the gastric mucosa; misoprostol effectively replaces these depleted prostaglandins to restore mucosal defenses.
Beyond its gastrointestinal applications, misoprostol possesses potent uterotonic properties. It increases uterine contractility and induces cervical relaxation, making it a valuable adjunctive therapy for reproductive indications such as pregnancy termination, management of pyometra/metritis, and post-mismating protocols.
Clinical Pearl: While it has been investigated for atopic dermatitis and cyclosporine-induced nephrotoxicity, its use for these conditions is generally secondary due to modest efficacy and the prevalence of gastrointestinal side effects.
Mechanism of action
Misoprostol exerts its effects through multiple prostaglandin (EP) receptors across different organ systems:
- Gastric Acid Suppression: Binds directly to EP3 receptors on gastric parietal cells → inhibits adenylate cyclase → decreases intracellular cAMP → reduces the activity of the apical H+/K+ ATPase proton pump → decreased basal and stimulated gastric acid secretion.
- Gastric Cytoprotection: Binds to EP receptors on superficial foveolar epithelial cells → stimulates the secretion of protective mucin and bicarbonate. It also increases mucosal blood flow and accelerates epithelial cell turnover, enhancing the overall mucosal barrier and healing capacity.
- Reproductive Tract: Binds to EP receptors in the myometrium → increases intracellular calcium concentrations → increases the amplitude and frequency of uterine contractions. It also induces collagen breakdown in the cervix, leading to cervical softening and dilation.
Safety & warnings
Contraindications
- Pregnancy (unless being used specifically as an abortifacient)
- Nursing mothers (can cause severe diarrhea in nursing offspring)
- Known sensitivity to prostaglandins or prostaglandin analogs
- Pregnant animals (unless being used specifically to induce abortion)
Adverse effects
- Diarrhea
- Abdominal pain
- Vomiting
- Flatulence
- Uterine contractions (in females)
- Vaginal bleeding (in females)
- Diarrhoea
- Nausea
- Abortion
Precautions
WARNING FOR PREGNANT WOMEN: Misoprostol is a potent abortifacient. Pregnant women or women who may become pregnant should handle this drug with extreme caution (e.g., wearing gloves or avoiding handling altogether).
- Use with caution in patients with cerebral or coronary vascular disease. While not explicitly reported with misoprostol, other prostaglandins have precipitated seizures in epileptic patients and caused hypotension.
- Adverse GI effects are common but often transient; they can be minimized by adjusting the dose or administering the drug with food.
Drug interactions
May aggravate misoprostol-induced diarrhea. If an antacid is required, an aluminum-only antacid is preferred.
May exacerbate renal dysfunction
Human combination products (misoprostol + diclofenac) are highly toxic to small animals due to different NSAID pharmacokinetics
Monitoring
- Clinical efficacy (resolution of ulcer signs, successful pregnancy termination, etc.)
- Adverse effects (GI distress, diarrhea, vomiting)
- Vaginal bleeding or discharge (if used in females)
- Resolution of clinical signs of gastric ulceration (e.g., vomiting, melena, anorexia)
- Monitoring for adverse GI effects (diarrhoea, abdominal pain)
Pharmacokinetics
Half-life
Absorption
Approximately 88% of an oral dose is rapidly absorbed from the GI tract. The presence of food and antacids will delay absorption. Undergoes significant first-pass metabolism.
Distribution
Both misoprostol and its active acid metabolite are highly bound to plasma proteins (approximately 90%). It is unlikely that misoprostol enters maternal milk, but it is unknown if the active acid metabolite does.
Metabolism
Rapidly de-esterified in the liver to its primary active metabolite, misoprostol acid. Misoprostol acid is further biotransformed via oxidative mechanisms to pharmacologically inactive metabolites.
Elimination
Metabolites, free acid, and small amounts of unchanged drug are principally excreted into the urine.
Overdose
Information on acute toxicity is limited. Overdoses in laboratory animals have produced:
- Diarrhea and emesis
- GI lesions
- Tremors and seizures
- Focal cardiac, hepatic, or renal tubular necrosis
- Hypotension
Treatment: Overdoses should be treated seriously. Employ standard gut-emptying techniques (e.g., emesis induction, activated charcoal) when applicable and safe. Treat resultant toxicity symptomatically with supportive care (e.g., IV fluids for hypotension and GI fluid loss).
Available products
Formulations
- Compounded cream
- Vaginal suppository (compounded/off-label use of tablets)
- Oral: 200 μg tablet
Human-labeled
- Misoprostol Tablets: 100 micrograms & 200 micrograms (Cytotec, generic)
- Cytotec 200 μg tablets
Regulatory status
POM (Prescription Only Medicine). Human product used under the cascade.
POM (Prescription Only Medicine). Human product used under the cascade.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Misoprostol tablets should be stored in well-closed containers at room temperature. After manufacture, misoprostol has an expiration date of 18 months.
Client information
CRITICAL WARNING FOR PREGNANT WOMEN: This medication can cause uterine contractions and miscarriage. Pregnant women, or women trying to conceive, should not handle this medication. If handling is absolutely necessary, strict precautions (such as wearing disposable gloves) must be taken.
- Gastrointestinal Upset: The most common side effects are diarrhea, abdominal cramping, and vomiting. These are often temporary and resolve over a few days as your pet's body adjusts to the medication.
- Administration: Giving this medication with food can help minimize stomach upset and diarrhea.
- When to Call the Vet: If diarrhea becomes severe, persists for more than a few days, or if your pet becomes lethargic, contact your veterinarian. They may need to adjust the dose or recommend a specific antacid (avoid magnesium-containing antacids as they worsen diarrhea).
- Female Pets: If given to an intact female dog, you may notice vaginal bleeding or discharge due to the drug's effect on the uterus.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.