Nizatidine
Also known as: Axid AR · Axid Pulvules · LY-139037 · nizatidinum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| As a prokinetic agent | 2.5-5 mg/kg PO once daily | PO | once daily | — | 🌎 NA |
| As an H2 blocker to reduce gastric acid production | 5 mg/kg PO once daily | PO | once daily | — | 🌎 NA |
- As an H2 blocker to reduce gastric acid production: Dosage not well established
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| As a colonic prokinetic agent | 2.5-5 mg/kg PO once daily | PO | once daily | — | 🌎 NA |
| As a colonic prokinetic agent (in combination with cisapride) | 2.5-5 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
- As a colonic prokinetic agent (in combination with cisapride): Used in combination with cisapride
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Nizatidine is an H2-receptor antagonist structurally and pharmacologically similar to ranitidine. While it possesses acid-suppressing capabilities like cimetidine and famotidine, its primary utility in veterinary medicine (particularly small animal practice) stems from its prokinetic properties.
- Used to manage delayed gastric emptying, intestinal pseudo-obstruction, and feline constipation/megacolon.
- May help prevent hemorrhagic necrosis in feline pancreatitis.
Clinical Pearl: Nizatidine is less commonly used today due to the availability of more potent acid suppressants (like proton pump inhibitors) and other prokinetics, but it remains a viable option, especially when dual acid-suppressing and prokinetic action is desired.
Mechanism of action
- Acid Suppression: Competitively inhibits histamine at the H2 receptors on gastric parietal cells → reduces basal and stimulated gastric acid output → decreases pepsin secretion.
- Prokinetic Action: Inhibits acetylcholinesterase → prevents breakdown of acetylcholine → increases acetylcholine concentrations at muscarinic receptors → stimulates GI motility.
- May also exert direct agonist effects on M3 muscarinic receptors.
- Increases lower esophageal sphincter (LES) pressure.
Safety & warnings
Contraindications
- Hypersensitivity to nizatidine
Adverse effects
- Anemia (rare)
- Headache/dizziness (rare)
- Rash/pruritus (rare)
- Cholinergic effects at high doses
Precautions
Use cautiously and consider reduced dosage in patients with diminished renal function. Monitor serum ALT in high-dose, chronic therapy. Geriatric patients or those with hepatic insufficiency require caution. False positive tests for urobilinogen may occur.
Drug interactions
May negate the prokinetic effects of nizatidine
May increase salicylate levels in patients receiving high doses of aspirin
Monitoring
- Clinical efficacy (decrease in symptoms, endoscopic examination, blood in feces)
- Serum ALT values (in high dose, chronic therapy)
Pharmacokinetics
Absorption
Rapid and nearly complete oral absorption with minimal first-pass effect in dogs. Food enhances absorption but is not clinically important.
Distribution
Marginally bound to plasma proteins. Unknown if it enters the CNS. Excreted in maternal milk at 0.1% of oral dose.
Metabolism
Metabolized in the liver to several metabolites, including at least one active metabolite.
Elimination
Over 50% excreted unchanged in the urine in animals with normal renal function.
Overdose
Single oral doses up to 800 mg/kg were not lethal in dogs. Overdose may cause cholinergic effects (lacrimation, salivation, emesis, miosis, diarrhea). Treat supportively and symptomatically.
Available products
Formulations
- Tablets
- Capsules
- Oral Solution
Human-labeled
- Nizatidine Tablets: 75 mg (Axid AR)
- Nizatidine Capsules: 150 mg & 300 mg (Axid Pulvules, generic)
- Nizatidine Oral Solution: 15 mg/mL in 480 mL (Axid)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store oral tablets and capsules in tight, light-resistant containers at room temperature.
Client information
- Consistency is Key: Administer this medication exactly as prescribed by your veterinarian. Missing doses can cause your pet's symptoms (like vomiting or constipation) to return.
- Tolerability: Nizatidine is generally very well tolerated by dogs and cats.
- What to Watch For: Contact your vet if you notice excessive drooling, tearing, vomiting, or diarrhea, as these could be signs of an overdose.
Note: Do not give your pet any over-the-counter antacids or other medications without consulting your veterinarian, as they may interact with nizatidine.
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.