Pharmacokinetics of intravenous, plain oral and enteric-coated oral omeprazole in the horse.

The research article is about a study that explored the pharmacokinetics of omeprazole administered in different forms and conditions in horses. It was found that enteric-coated oral omeprazole, particularly when the horses were fasted, had a higher bioavailability compared to the other methods of administration.

Study Design

• The goal of the study was to understand how omeprazole, a medication often used for gastric ulcers in horses, behaves in the horse’s body and how its rate of absorption and overall availability can be influenced by different methods of administration.
• Twelve horses served as the subjects of the experiment, which consisted of four different treatment groups: fasted state intravenous omeprazole (IV-Fasted), fasted state enteric-coated oral omeprazole (ECO-Fasted), fed state enteric-coated oral omeprazole (ECO-Fed), and fasted state plain oral omeprazole (PL-Fasted).
• The respective pharmacokinetic properties of these different applications were then tracked and recorded, using UHPLC-MS (Ultra High-Performance Liquid Chromatography-Mass Spectrometry) to determine plasma omeprazole concentrations.

Results and Findings

• Higher rates of bioavailability (the amount of the drug that is able to be absorbed and used by the body) were discovered among the horses in the ECO-Fasted group, in relation to those in the PL-Fasted group.
• Similarly, the area under the curve or AUC, representing the total drug exposure over time, was higher in the ECO-Fasted group compared to the PL-Fasted group.
• There were no consequential differences found between the ECO-Fasted and ECO-Fed groups in terms of bioavailability, peak concentration (Cmax), time to reach peak concentration (Tmax), or AUC.
• When the half-life data from the oral formulations was combined, it was discovered to be longer than the half-life found in the IV-Fasted group. This indicates the drug stayed in the horse’s system longer when administered orally.

Conclusions

• The study concluded that enteric-coated omeprazole showed higher bioavailability than previously believed, with feeding having minor effects.
• The bioavailability of plain omeprazole was about half that of the enteric-coated form, emphasizing the advantage of the enteric-coating.
• The longer half-life found following oral administration is in line with a common pharmacokinetic phenomenon known as the “flip-flop effect”, which hadn’t been previously reported for omeprazole in horses.