Comparison of paste and suspension formulations of omeprazole in the healing of gastric ulcers in racehorses in active training

OBJECTIVE: To compare effects of a commercially available omeprazole paste and a compounded omeprazole suspension on healing of gastric ulcers in Thoroughbred racehorses in active training. DESIGN: Randomized controlled trial. ANIMALS: 32 horses with gastric ulcers. PROCEDURE: Horses were assigned to 2 groups on the basis of endoscopic gastric ulcer severity. Group-1 horses were treated with omeprazole suspension for 30 days and with omeprazole paste for an additional 30 days. Group-2 horses were treated with omeprazole paste for 30 days and omeprazole suspension for an additional 30 days. Serum omeprazole concentrations were measured in 4 additional healthy horses after administration of a single dose of each formulation. In all instances, omeprazole was administered at a dose of 4 mg/kg (1.8 mg/lb), p.o.. RESULTS: Ulcer severity scores on day 0 were not significantly different between groups. On day 30, ulcer severity score was significantly decreased, compared with day-0 score, in group-2 but not in group-1 horses. On day 60, ulcer severity score was significantly decreased, compared with day-0 and day-30 scores, in group-1 horses. In group-2 horses, ulcer severity score on day 60 was significantly lower than the day-0 score but was not significantly different from the day-30 score. Maximum observed serum omeprazole concentration and area under the concentration-time curve were significantly higher after administration of the paste versus the suspension formulation. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that although administration of the commercially available paste omeprazole formulation was effective in promoting healing of gastric ulcers in these horses, administration of the compounded omeprazole suspension was ineffective.