How Does Omeprazole Work and Why Does It Matter?

How Does Omeprazole Work and Why Does It Matter?

Make sure your horse’s ulcer medication is formulated to work correctly.

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Equine stomach ulcers are a common problem, with more than 50 percent of horses being affected.1 Ulcers can affect any horse of any age. There are many ulcer medications on the market – so how do you know which one actually works?

First, let’s look at how ulcers form. The horse’s stomach is designed to digest a steady stream of grass throughout the day.2 With common feeding and housing practices, there may be times during the horse's day when the stomach is devoid of feed material, exposing the unprotected part of the stomach to the strong gastric acid that is still being produced. Ulcers are less likely to form when acid exposure to the top part of the stomach is reduced.3

Omeprazole, a common ulcer treatment and prevention medication, inhibits acid production at the source – the proton pumps at the bottom of the stomach. Like many other oral medications, omeprazole must pass through the stomach to be absorbed by the small intestine in order for it to work as intended – decreasing acid production (described in detail below). But by nature, omeprazole isn’t very stable and is easily degraded in an acidic environment. In fact, human forms of the medication are labeled “do not crush or chew,” because a special coating is needed to protect the omeprazole and ensure it makes it into the small intestine.4

 Let’s consider the path omeprazole takes when given to a horse:

  1. Omeprazole is swallowed and passes through the esophagus and into the stomach.
  2. The omeprazole spends a period of time in the highlyacidic part of the stomach before moving into the small intestine.
  3. Omeprazole is then absorbed through the lining of the small intestine into the bloodstream and travelsthrough the blood vessels, back to the stomach where it inhibits the action of the proton pump, decreasing acid production.

Because stomach acid can degrade the omeprazole, it must be protected to ensure it makes it into the small intestine.

In equine medicine, only Gastrogard® (omeprazole), by Merial, and Ulcergard® (omeprazole), by Merial, have a patented formulation that protects the omeprazole from being broken down by stomach acid, ensuring their effectiveness and value. They are the only two FDA-approved products for treatment and prevention of equine gastric ulcers. Without the proper formulation, omeprazole may be degraded in the stomach and has little to no effect.  

Compounded omeprazole and illegally marketed over-the-counter omeprazole products are commonly used throughout the equine industry. However, these products have not gone through FDA approval to ensure their safety and effectiveness, and some compounded formulations have been shown to be ineffective in treating ulcers at a 4mg/kg dose daily for thirty days.5

“For ulcer prevention, make sure to give ULCERGARD starting 48 hours prior to and continuing through a stressful event such as training, traveling, stall confinement and competition,” says Hoyt Cheramie, DVM, MS, DACVS, Senior Equine Professional Services Veterinarian, Boehringer Ingelheim. “This ensures maximal effect of the medication during the time it’s most needed.”  

When it comes to your horse’s gastric health, don’t be fooled by omeprazole that isn’t formulated correctly. Get real treatment and real prevention of equine gastric ulcers with GASTROGARD and ULCERGARD, respectively. 

IMPORTANT SAFETY INFORMATION: The safety of GASTROGARD paste has not been determined in pregnant or lactating mares. For use in horses and foals 4 weeks of age and older. Keep this and all drugs out of the reach of children. In case of ingestion, contact a physician.

IMPORTANT SAFETY INFORMATION:ULCERGARD can be used in horses that weigh at least 600 lbs. Safety in pregnant mares has not been determined. Not for use in humans. Keep this and all medications out of the reach of children. In case of ingestion, contact a

GASTROGARD and ULCERGARD are Merial products. Merial is now part of Boehringer Ingelheim.

®GASTROGARD and ULCERGARD are registered trademarks of Merial. ©2018 Merial, Inc., Duluth, GA. All rights reserved. EQU-0704-EGUS0518.

1Sykes BW, Hewetson M, et al. European College of Equine Internal Medicine Consensus Statement – Equine Gastric Ulcer Syndrome in Adult Horses. J Vet Intern Med. 2015;29:1288-1299.
2Williams C. The Basics of Equine Nutrition. Available at: Accessed April 3, 2017.
3Equine Gastric Ulcer Council. Recommendations for the diagnosis and treatment of Equine Gastric Ulcer Syndrome (EGUS). Equine Vet Educ. 1999;11:262-272.
4Avoid the crush: Hazards of medication administration in patients with dysphagia or a feeding tube. CMAJ. 2005;172(7):871-872.
5Nieto JE, et al. Comparison of paste and suspension formulations of omeprazole in the healing of gastric ulcers in racehorses in active training. J Am Vet Med Assoc. 2002;8:1-5.

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Innovative medicines for people and animals have for more than 130 years been what the research-driven pharmaceutical company Boehringer Ingelheim stands for. Boehringer Ingelheim is one of the industry’s top 20 pharmaceutical companies and to this day remains family-owned. Day by day, some 50,000 employees create value through innovation for the three business areas human pharmaceuticals, animal health and biopharmaceutical contract manufacturing. In 2016, Boehringer Ingelheim achieved net sales of around 15.9 billion euros.

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