Normal dogs treated with famotidine for 14 days have only transient increases in serum gastrin concentrations.

Abstract

BACKGROUND: In people, serum gastrin concentrations increase in response to administration of H(2) receptor antagonists, but the effect of famotidine administration on serum gastrin concentrations has not been evaluated in dogs. OBJECTIVES: To determine if serum gastrin concentrations increase in response to 14 days of famotidine treatment and the time needed to return to baseline after discontinuation of famotidine; define stability of gastrin in samples held at room temperature. ANIMALS: Eleven healthy dogs were included in part A (famotidine treatment) and 7 healthy dogs in Part B (serum gastrin stability). In part A, famotidine (0.5 mg/kg p.o. q12h) was administered for 14 days. Fasting blood samples were collected on days 0, 3, 7, 11, 14, 16, 18, 20, and 22. In part B, blood was collected after a 12-hour fast. Gastrin concentrations in serum samples held at room temperature for ≤30 minutes after sampling were compared to concentrations in samples held at room temperature for 150 minutes after sampling. RESULTS: Serum gastrin concentrations increased by day 3 of famotidine administration and returned to baseline concentrations in all dogs by day 14 despite continued famotidine administration. Serum gastrin concentrations were lower (20% mean decrease; P = .0005) in samples held at room temperature for 150 minutes. CONCLUSIONS AND CLINICAL IMPORTANCE: After 14 days of famotidine administration, clinically healthy dogs have normal serum gastrin concentrations. In a dog with clinical features consistent with gastrinoma, chronic famotidine administration is unlikely to contribute to increases in serum gastrin concentrations.