Pharmacokinetics and efficacy of intravenous famotidine in adult cattle

BACKGROUND: Abomasal ulceration is recognized in neonatal and adult cattle, but research regarding treatment is limited. Histamine‐2 receptor antagonists (H(2)RA), such as famotidine, are used clinically with little evidence‐based research about efficacy in adult cattle. HYPOTHESIS AND OBJECTIVES: Intravenous famotidine administered at 0.4 mg/kg will increase the pH of abomasal outflow digesta compared to saline control in adult cattle. The objectives were to assess the effect of famotidine, administered as a single dose and as multiple doses, on abomasal outflow fluid pH in adult cattle. A third objective was to describe the pharmacokinetic parameters of IV famotidine in cattle. ANIMALS: Four clinically healthy adult Angus‐cross steers previously fitted with duodenal cannulae placed orad to the biliary and pancreatic ducts. METHODS: Randomized, 2‐way cross‐over clinical trial. Steers received IV famotidine (0.4 mg/kg) as a single and 3‐dose regimen (every 8 hours) versus saline control. Blood for analysis of serum famotidine concentration was collected intermittently for 12 hours, and abomasal outflow fluid pH was measured at intervals for a 24‐hour period. After a 34‐hour washout period, the opposite treatments were administered and the sampling repeated. RESULTS: Abomasal outflow fluid pH was higher in steers treated with famotidine for up to 4 hours after a single dose but the effect decreased with subsequent doses. The median (range) elimination half‐life was 3.33 (3.21‐3.54) hours. CONCLUSIONS AND CLINICAL IMPORTANCE: Famotidine may be useful for treatment or prevention of abomasal ulceration in adult cattle, but the duration of effect may decrease with time.