Fast Famotidine, PPI Pantoprazole, or Both?

In critically ill dogs, GI bleeding is a common complication with many causes, including NSAID toxicosis, liver failure, and GI neoplasia. Treatment includes acid-suppressant administration to increase the gastric pH. Famotidine works within hours compared to a proton pump inhibitor (PPI) such as pantoprazole, which takes several days to reach peak effect. Many veterinarians administer the rapidly acting famotidine in the first few days in combination with the slower-acting pantoprazole to critically ill dogs with high risk for GI bleeding, but there is no evidence demonstrating an advantage with this combination. Many pharmacologists argue that combination therapy may interfere with the efficacy of the PPI. In this randomized crossover study, gastric pH changes over a 3-day period were compared in healthy dogs (n = 12) given IV famotidine with pantoprazole or pantoprazole alone. All treatments were dosed at 1 mg/kg IV q12h for 3 days, and continuous intragastric pH monitoring was performed. In humans, mean percentage time (MPT) intragastric pH ≥3 is the ideal baseline for GI ulceration healing; MPT ≥4 is ideal for healing of gastroesophageal reflux lesions. No significant differences were found between the MPT that gastric pH was ≥3 and ≥4 between the 2 groups in this study. The monotherapy group also remained above target pH levels for longer periods than the combination-therapy group. There appears to be no advantage to giving famotidine in addition to pantoprazole for increasing gastric pH.

Commentary

PPIs such as pantoprazole reach peak effect after 4 days of therapy, which is why many veterinarians co-administer famotidine during the first several days of treatment. The work presented here shows that there is no difference in acid suppression between PPI monotherapy and combined treatment with pantoprazole and famotidine. Practitioners are also reminded that previous research has shown that q12h PPI administration can provide superior acid suppression compared to q24h dosing. This research adds to what is known about optimal acid suppression therapy in dogs, moving our profession toward an understanding of how to best treat dogs with GI bleeding.—Julie M. Walker, DVM, DACVECC