Ranitidine
Ranitidine is a histamine h2-receptor antagonist.
Group
Histamine H2-receptor antagonist
Mechanism of Action
Decreases histamine-stimulated gastric acid secretion; sustained suppression is generally weaker than with proton pump inhibitors.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Gastric acid suppression | 2 mg/kg | IV, PO | Every 8 h | |
| Esophagitis | 1–2 mg/kg | PO | Every 12 h | |
| Chronic gastritis | 0.5 mg/kg | PO | Every 12 h | |
| Gastric ulcer disease | 0.5–2 mg/kg | PO, IV, IM | Every 8–12 h | |
| Gastric ulcer disease | 1–2 mg/kg | PO, IV, SC | Every 12 h | |
| Gastrinoma | 1–2 mg/kg | PO, IV, SC | Every 8–12 h | |
| Renal disease-associated hypergastrinemia | 1–2 mg/kg | PO | Every 12 h | |
| Gastric prokinetic treatment | 1–2 mg/kg | PO | Every 12 h |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Gastric acid suppression | 2.5 mg/kg | IV | Every 12 h | |
| Gastric acid suppression | 3.5 mg/kg | PO | Every 12 h | |
| Gastric acid suppression | 1–2 mg/kg | PO, IV, SC | Every 12 h | |
| Colonic prokinetic treatment | 1–2 mg/kg | PO | Every 8–12 h |
Horses
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Gastric acid suppression | 2.2–6.6 mg/kg | PO | Every 6–8 h | Higher reported dose gives greater acid suppression. |
| Gastric acid suppression | 2 mg/kg | IV | Every 6–8 h | |
| Foal acid suppression | 1.5 mg/kg | IV | Every 8 h | |
| Foal acid suppression | 6.6 mg/kg | PO | Every 8 h | |
| Acid suppression | 1.5–2 mg/kg | IV, IM | Every 6–8 h |
Cattle
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Gastric acid suppression in milk-fed calves | 50 mg/kg | PO | Every 8 h | |
| Gastric acid suppression in adults | 6.6 mg/kg | IM | Reported experience indicates only about 1 hour of effect. |
Rabbits
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Gastric ulceration | 2–5 mg/kg | PO | Every 12 h | |
| Prokinetic adjunct | 0.5 mg/kg | IV | Every 24 h | Reported with cisapride 0.5 mg/kg orally every 8 hours. |
Indications
- Gastric acid suppression
- Reported prokinetic use
- Esophagitis
- Chronic gastritis
- Gastric ulcer disease
- Gastrinoma
- Renal disease-associated hypergastrinemia
- Gastric prokinetic treatment
- Colonic prokinetic treatment
- Foal acid suppression
- Acid suppression
- Gastric ulceration
- Prokinetic adjunct
Contraindications
- Reduced renal clearance can increase exposure.
Interactions
- Reduces absorption of acid-dependent drugs including azole antifungals and iron.
Adverse effects
- CNS effects are possible at high exposure; product impurity quality matters.
Toxicity
High exposure may cause tremor, vomiting and rapid respiration; manage clinical effects supportively and account for renal elimination.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Ranitidine reformulated tablet 150 mg | Tablet | 150 mg / tablet | PO |
| Ranitidine reformulated tablet 300 mg | Tablet | 300 mg / tablet | PO |
Monitoring and Administration
Monitor acid-related disease response and renal function when relevant. Historical stock and newly reformulated products should not be treated as equivalent in quality assurance.
Earlier guidance describes historical NDMA-related withdrawal. Reformulated tablets have subsequently been approved; availability and quality remain product-specific.
Ranitidine-bismuth-citrate 24 mg/kg orally every 8-12 hours plus clarithromycin 12.5 mg/kg for 14 days in ferrets is a different combination ingredient and is not a ranitidine-only dose. The unusually high foal 6.6 mg/kg IV every 4 hours differs materially from other IV regimens and needs independent route/unit clarification.