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Analyzing gastric acid suppressants in cats

Parkinson S, Tolbert K, Messenger K, et al. Evaluation of the effect of orally administered acid suppressants on intragastric pH in cats. J Vet Intern Med. 2015 Jan; 29(1):104-112.

Ulcers can occur in the stomach and upper small intestine (duodenum) when the protective mechanism of the stomach is compromised. There are several gastric and non-gastric disorders that may disrupt the mucosal barrier: neoplasia, liver failure, critical illness, drug toxicity, gastrointestinal infections (e.g.,
Helicobacter), and inflammatory bowel disorders are among the possibilities. The most common gastric acid suppressants prescribed to prevent GI erosion and ulceration includes histamine-2 receptor antagonists (H2RA) –famotidine, and proton pump inhibitors (PPIs) – omeprazole products.

There are several obstacles that make optimal dosing of commercial omeprazole formations in the cat not possible. One such issue is the omeprazole suspension approved for humans contains a substance potentially toxic to cats (xylitol) and is also flavored inappropriately for cats. The capsules of Omeprazole are most commonly available in sizes that make dosing for cats difficult. Omeprazole tablets can be manipulated more easily but contain a protective coating to prevent premature breakdown in the stomach.

With these obstacles in mind, the authors planned a study to compare the effect of orally administered famotidine, fractionated omeprazole tablet (fOT), and omeprazole reformulated paste (ORP) –an equine product- on intragastric pH in cats. The omeprazole paste was reformulated to a suspension by mixing an approved oral paste for horses in cod liver oil. Six healthy adult cats were part of a randomized, 4-way crossover study where the cats received 0.88-1.26 mg/kg orally every 12 hours fOT, ORP, famotidine, and placebo (lactose capsules). A Bravo intragastric pH capsule was used to continuously monitor pH for 96 hours starting on day 4 of dosing.

The results of the study showed that the omeprazole formulations provide superior acid suppression compared to famotidine and placebo. Famotidine was still more efficacious than placebo but inferior to omeprazole in acid suppression. Only the omeprazole formulations came close to the goals used for treatment of people with GI ulcers and gastroesophageal reflux. There was no statistical difference noted in the presence of adverse events (inappetence, vomiting, diarrhea) in any of the acid suppressants evaluated. It appears that omeprazole paste and fractionated omeprazole tablets, along with famotidine, are generally well tolerated. It appears that enteric-coated omeprazole tables are effective for acid suppression in spite of the disruption of the enteric coating.  (VT)

See also:

Tolbert MK, Odunayo A, et al. Efficacy of intravenous administration of combined acid suppressants in healthy dogs. J Vet Intern Med. 2015 Feb. 25.