What are some common medications used for the treatment of ulcers?

Equine gastic ulcer syndrome (EGUS) is a highly prevalent condition in the modern horse. Fortunately, there are numerous chemical and herbal treatments now available on the market that are proven effective in tackling this frustrating disease. That being said, a change in management is often needed to help keep ulcer-prone horses healthy and productive in their day to day activities. Since such a large number of treatments are available, we will discuss chemical treatments in this Feed For Thought and herbal treatments in the next to properly address all options available to horse owners.
One of the most prevalent treatments for EGUS is products containing omeprazole. Omeprazole is a “proton pump inhibitor” which means it blocks the direct release of acid into the stomach (Plumb, 896). Contrary to common belief, this is not a physical blockage or coating of the stomach lining. Instead, omeprazole passes through the stomach, is absorbed in the small intestine, enters the blood, and is then distributed primarily to the gastric parietal cells, or the cells that produce acid and release it into the stomach. The goal of omeprazole is to reduce the acidity of the stomach long enough to allow the body’s natural repair mechanisms to heal any existing ulcers.

One should be aware that omeprazole can impede in the digestion of protein, which normally starts in the stomach with acid and pepsin, a protein-digesting enzyme only active in an acidic environment. Since the proteins are not digested, the horse may experience protein deficiencies or even develop sensitivities since the undigested proteins may activate an immune response further down in the digestive tract. The daily use of omeprazole is safe up to 90 days, at which point the benefits may be outweighed by the side effects associated with long term use. It is also prudent that one carefully weans a horse off omeprazole since this drug is highly tied to a phenomenon known as acid rebound hypersecretion (Fullarton et al., 1991). Acid rebound hypersecretion is when the body will secrete abnormally high amounts of acid after using a proton pump inhibitor, often causing ulcers worse than the original ones being treated. To avoid acid rebound, one should gradually wean the horse off the omeprazole over the course of a week.

Another drug available is ranitidine which, instead of blocking acid production like omeprazole, simply reduces the amount of acid released. It does this by blocking the receptors that, when triggered, would normally tell the stomach to release more acid (Plumb, 1076). A key distinction between the two is that ranitidine reduces acid production while omeprazole halts the release of acid into the stomach. However, neither drug actually heals ulcers; instead, they both reduce the acidic assault on the stomach lining long enough for the horse’s healing capabilities to take effect. Ranitidine is also a prokinetic agent, meaning it helps increase gut motility, thereby making it an excellent choice for ulcer prevention while traveling. Overall, ranitidine is a very safe drug for the otherwise healthy horse, though it can inhibit the absorption of some B vitamins. The downside of ranitidine is that the effect only lasts for 8 hours. This can be a management issue for some since the medication is best used when administered three times daily at 8 hour intervals.

The last drug commonly used for the treatment of EGUS is sucralfate, though this is usually reserved for the most serious ulcer cases. Sucralfate is a physical gastroprotectant, meaning it works to directly coat the stomach lining and is largely unabsorbed by the horse (Plumb, 1130). When sucralfate is ingested, it reacts with the acid in the stomach forming a paste-like substance. This paste will bind to exposed ulcers and help protect them from bile, acid, or pepsin found in the stomach without any sort of reduction in acid production. Only once the caustic agents are no longer damaging the ulcerated stomach lining can the slow healing process begin. Unfortunately, sucralfate must be given on an empty stomach and cannot be given with a large number of other drugs since it will greatly inhibit their absorption. The same holds true for many vitamins and minerals, particularly fat soluble vitamins such as vitamin E and vitamin K, making it not an ideal choice for long-term use. Sucralfate should also be given at least two hours before any supplements or oral medications to minimize these effects.

Fullarton, GM, AM Macdonald, KE McColl. “Rebound hypersecretion after H2-anagonist withdrawal – a comparative study with nizatidine, ranitidine, and famotidine.” 1991. Alimentary Pharmacology & Therapeutics. 5(4):391-8.
Plumb, Donald C. “Omeprazole.” Plumb’s Veterinary Drug Handbook. Ames: Blackwell Publishing, 2008.
896-899. Print.
Plumb, Donald C. “Ranitidine HCL.” Plumb’s Veterinary Drug Handbook. Ames: Blackwell Publishing,
2008. 1076-1078. Print.
Plumb, Donald C. “Sucralfate.” Plumb’s Veterinary Drug Handbook. Ames: Blackwell Publishing, 2008.
1130-1131. Print.