Preliminary investigations into a novel, long-acting, injectable, intramuscular formulation of omeprazole in the horse.
Authors: Sykes B W, Kathawala K, Song Y, Garg S, Page S W, Underwood C, Mills P C
Journal: Equine veterinary journal
Summary
# Editorial Summary: Long-Acting Injectable Omeprazole in Horses Gastric ulceration remains a prevalent and therapeutically challenging condition in equine practice, with standard oral omeprazole requiring daily dosing to maintain adequate acid suppression. Researchers investigated a novel intramuscular formulation of long-acting omeprazole (LA-OMEP), conducting both a pharmacodynamic study in six Thoroughbreds with gastric cannulas and a clinical efficacy trial in 26 horses with endoscopically confirmed squamous or glandular gastric disease. A single 2.0-g injection maintained intragastric pH above 4 for more than 66% of each day for four consecutive days in all horses studied, with four of six horses sustaining this effect through day seven. Clinical outcomes proved equally promising: all 22 horses with squamous ulceration healed completely, whilst nine of 12 with glandular disease showed complete healing, with improvement observed across all remaining cases and no worsening recorded. These results suggest LA-OMEP offers equivalent or superior efficacy to conventional daily oral dosing, potentially improving compliance and reducing handler burden in managing both acute ulceration and chronic disease, though validation in larger cohorts and assessment of cost-effectiveness relative to standard protocols will be essential before widespread adoption.
Read the full abstract on PubMed
Practical Takeaways
- •This long-acting injectable omeprazole formulation may offer a practical alternative to daily oral dosing for managing gastric ulcers in horses, with evidence of efficacy comparable to conventional oral therapy
- •Two injections spaced 7 days apart appear effective for squamous gastric disease (100% healing rate) and show promise for glandular disease (75% healing rate)
- •The formulation's ability to maintain therapeutic pH for several days per injection could improve compliance and reduce handling stress associated with daily oral medication
Key Findings
- •A single 2.0 g intramuscular injection of long-acting omeprazole maintained intragastric pH above 4 for >66% of the time for 1-4 days in all horses, and up to 7 days in four of six horses
- •100% (22/22) of horses with squamous gastric disease showed complete healing following two injections 7 days apart
- •75% (9/12) of horses with glandular gastric disease achieved complete healing, with 100% showing improvement of at least one grade
- •No worsening of lesions was observed in any horse, and lesion grade decreased significantly over time in both squamous (P<0.0001) and glandular (P=0.0024) mucosa