Famotidine

H₂-Receptor Antagonist (Systemic Drug)

Prescriber Highlights

• Used to reduce gastric acid production

• Recent studies in dogs found famotidine was inferior to omeprazole for increasing gastric pH

Uses, Indications

Used for treatment and/or prophylaxis of gastric and duodenal ulcers, uremic gastritis, stress-related or drug-induced erosive gastritis, esophagitis, duodenal gastric reflux, and esophageal reflux

Contraindications, Precautions, Warnings

• Contraindications

Patients with hypersensitivity to famotidine 

• Precautions

Geriatric patients and patients with significantly impaired hepatic or renal function or severe cardiac disease

• Warnings

Rapid IV infusion may cause bradycardia

Side Effects

• Relatively safe; adverse effects are minimal

• GI side effects (eg, anorexia, vomiting, diarrhea), headaches, and dry mouth or skin have been noted in humans

• Rarely, agranulocytosis has been noted when famotidine is used concomitantly with other drugs that can cause bone marrow depression

Drug Interactions

• Famotidine raises gastric pH and may decrease absorption of azole antifungals (eg, ketoconazole, itraconazole, fluconazole)

• Famotidine may decrease absorption of cefpodoxime and cefuroxime; giving with food may alleviate this effect

• Famotidine may decrease cyclosporine concentrations

• Famotidine may decrease absorption of oral iron salts; separate administration by at least 1 hour

• Unlike cimetidine or ranitidine, famotidine does not appear to inhibit hepatic cytochrome P450 enzymes, and dosage adjustments of other drugs (eg, warfarin, theophylline) metabolized by this pathway are usually not required

Monitoring

• Clinical efficacy; monitor decreases in clinical signs and examine endoscopically for persistent ulceration; monitor feces for blood

• Adverse effects, if noted

Client Information

• Doses are often administered 1 to 2 times per day; clinical signs may reoccur if doses are missed

• Works best if given before the first meal of the day

• If GI signs are noted, give with food

Dosage Forms

• No veterinary-labeled products are available 

• Human-labeled products available for extra-label use include: 

  • Famotidine oral tablets and gelcaps: 10 mg, 20 mg, 40 mg

  • Famotidine injection: 10 mg/mL

—Compiled and summarized from Plumb’s Veterinary Drugs by Shannon Palermo, VMD

Information about this drug was adapted from Plumb’s Veterinary Drugs. Further details and more therapeutics can be found with a subscription at plumbsveterinarydrugs.com