Effects of misoprostol and omeprazole on basal gastric pH and free acid content in horses.

This study investigates the influence of two drugs, misoprostol and omeprazole, on the gastric pH and acid content in horses, ultimately revealing that both drugs successfully inhibit gastric acid secretion.

Study Details

• The study was performed on five young adult healthy horses. Their basal gastric pH and free acid content were measured every hour, for a period of eight hours.
• The observed pH and free acid content differed slightly per horse, with an overall average of 1.63 +/- 0.06 to 1.97 +/- 0.11 for pH, and 26.42 +/- 4.14 to 17.92 +/- 5.28 mmol litre-1 for the free acid content.

The Use of Misoprostol

• The horses were then given misoprostol, an analogue of prostaglandin, by oral administration. This drug is commonly used to prevent stomach ulcers and to induce labor or abortion in humans.
• The use of misoprostol resulted in a significant increase in the horses’ gastric pH, lasting about three to five hours post-administration. This was accompanied by a decrease of 80 to 90% in the gastric free acid content over the entire eight-hour observation period.

The Use of Omeprazole

• The researchers also tested the effects of omeprazole, a drug usually used in humans to reduce the amount of acid the stomach produces. This compound was given to the horses through intravenous administration.
• Just like misoprostol, omeprazole led to an increased gastric pH level, evidenced two to three hours after application. In addition, it brought about a decrease of 65 to 90% in the free acid content almost throughout the entire eight-hour period.

Conclusion

• The results confirmed the horses to be basal acid secretors, meaning they naturally produce a significant amount of gastric acid.
• Both drugs – misoprostol and omeprazole – were found to effectively inhibit this acid production in the stomach. This points to the crucial role of both prostaglandins and H+/K+-ATPase, an enzyme facilitating the exchange of hydrogen and potassium ions, in controlling the functionality of parietal cells in the horses’ gastric mucosa.