Preliminary investigations into a novel, long-acting, injectable, intramuscular formulation of omeprazole in the horse.

This research investigates a newly developed long-lasting injectable form of omeprazole in horses, showing that it was effective in suppressing stomach acid for up to a week from a single injection and aiding in the healing of gastric disease.

Objectives and Methodology

• The research aimed to understand the pharmacodynamics (how the drug works in the body) and the clinical efficiency of a new long-acting, injectable omeprazole formulation (LA-OMEP).
• The study was conducted in two parts: Part A, the pharmacodynamic study, and Part B, a small-scale clinical trial.
• In Part A, six adult Thoroughbreds with gastrotomy tubes were enrolled. For eight consecutive days, their intragastric pH was continuously monitored except for one hour daily. Each horse was given a single dose of LA-OMEP on day 1.
• In Part B, 26 horses diagnosed with either squamous or glandular gastric disease were enrolled based on routine gastroscopy. They were administered the LA-OMEP by injection on days 0 and 7, and their conditions were reevaluated through gastroscopy on days 14 (for 23 horses) or 16 (for one horse).

Findings

• The results from Part A showed successful acid suppression. The stomach pH was above 4 (a measure of low acidity) for more than 66% of the time during days 1-4 in all six horses, and for days 1-7 in four of those six.
• In Part B, healing was observed in all enrolled horses. Of the horses with squamous gastric disease, 100% showed healing, and of those with glandular disease, 75% displayed healing. Every horse with either type of gastric disease showed at least one grade of improvement, and no horse saw a worsening of lesions.
• Over time, the severity (grade) of the disease in both squamous and glandular mucosa (the stomach lining) decreased significantly. This suggests that LA-OMEP was effective in promoting healing and reducing gastric disease severity.

Conclusion

• The study sample size was small, which might limit the breadth of conclusions that could be drawn from the results.
• Despite this, the findings provided promising evidence regarding the efficacy of LA-OMEP in suppressing acid and treating gastric disease. The drug’s performance was comparable, if not superior, to effects noted in previous similar studies involving oral omeprazole therapy.