Drug Monograph
Full clinical overview, indications, dosage references & safety notes.
Drug Monograph
Full clinical overview, indications, dosage references & safety notes.
Overview
Famotidine is a histamine-2 (H2) receptor antagonist used in dogs and cats to decrease gastric acid secretion in a variety of gastrointestinal disorders associated with gastric hyperacidity or mucosal injury.
It is substantially more potent than cimetidine and is commonly used in the management of gastric and duodenal ulceration, erosive gastritis, and esophagitis. Although effective at increasing gastric pH, its acid-suppressive effect may diminish during prolonged daily administration.
Mechanism of Action (MOA): Famotidine competitively blocks histamine H2 receptors on gastric parietal cells, thereby inhibiting histamine-stimulated gastric acid secretion.
Indications
Famotidine is used in dogs and cats for the treatment and management of acid-related gastrointestinal disorders and conditions associated with excessive gastric acid production.
- Gastric and duodenal ulceration: Used to reduce gastric acidity and promote mucosal healing.
- Erosive gastritis: Including idiopathic, uremic, or drug-associated gastritis.
- Esophagitis: Helps reduce acid-mediated esophageal irritation and inflammation.
- Hypersecretory conditions: Such as gastrinoma, mast cell neoplasia, and short bowel syndrome.
Dosage (Reference)
Dog
In dogs, famotidine is administered orally for acid suppression in a variety of gastrointestinal conditions requiring reduction of gastric acidity.
| Clinical use | Route | Dose | Notes |
|---|---|---|---|
| All indications | PO | 0.5–1 mg/kg q12–24h | Dosing interval depends on severity and clinical response. |
• May be administered once or twice daily depending on patient needs.
• Effect on gastric pH may decrease during prolonged daily administration.
• Omeprazole may provide stronger acid suppression in some patients.
Cat
In cats, famotidine is used similarly to dogs for gastric acid suppression in acid-related gastrointestinal disorders.
| Clinical use | Route | Dose | Notes |
|---|---|---|---|
| All indications | PO | 0.5–1 mg/kg q12–24h | Adjust frequency according to clinical response. |
• Long-term daily administration may reduce effectiveness over time.
• Monitor clinical response and adjust therapy as needed.
Warnings & Precautions
Famotidine has a favorable safety profile in dogs and cats, but therapeutic response and long-term effectiveness should still be monitored during treatment.
- Reduced efficacy over time: Acid suppression may diminish with chronic daily administration.
- Variable acid suppression: Gastric pH elevation may be less pronounced than with proton pump inhibitors such as omeprazole.
- Not antiemetic: Famotidine reduces acid secretion but does not directly control nausea or vomiting.
- Combination therapy: Concurrent use with pantoprazole has not demonstrated superior benefit compared with pantoprazole alone.
Drug Interactions
Famotidine has relatively few clinically significant drug interactions compared with cimetidine because it has minimal effects on hepatic cytochrome P450 enzyme systems.
- Cytochrome P450–dependent drugs: Less likely to alter hepatic drug metabolism compared with other H2 receptor antagonists.
Side Effects & Overdose
Side Effects
Famotidine is generally well tolerated in dogs and cats, with adverse effects occurring infrequently.
- Gastrointestinal upset: Mild digestive disturbances may occasionally occur.
- Low adverse effect frequency: Side effects are generally less common than with cimetidine.
Overdose
Information regarding overdose in veterinary patients is limited, but toxicity is expected to be low because of the drug’s wide safety margin.
- Exaggerated adverse effects: Gastrointestinal signs may become more pronounced with excessive dosing.
- Management: Supportive care and clinical monitoring are generally sufficient.
Key Notes
Practical clinical points that help optimize the safe and effective use of famotidine in dogs and cats:
- Potent acid suppressant: Significantly more potent than cimetidine for suppression of gastric acid secretion.
- Minimal effect on GI motility: Does not significantly alter gastrointestinal motility.
- Transient gastrin elevation: Serum gastrin concentrations may increase temporarily during therapy.
- Flexible dosing interval: Can be administered once or twice daily depending on clinical needs.
- Widely used in GI support: Commonly incorporated into supportive treatment protocols for acid-related disease.
