Pharmacokinetic disposition of intravenous and oral pentoxifylline in horses.

This research focused on studying how the drug pentoxifylline behaves in the body (pharmacokinetics) of horses when administered intravenously and orally, and its metabolism into an alcohol metabolite. It revealed variable absorption in individuals depending on the route of administration and form, but made no specific recommendation for the most appropriate dosage or form for horses due to these inconsistencies.

Objective of the Research

• This study aimed to investigate the pharmacokinetics of the drug pentoxifylline, including how it was metabolized into an alcohol metabolite, in horses. Researchers examined how the drug behaved when administered in three different ways: intravenous administration, and oral administration via sustained-release tablets or crushed and mixed with corn syrup.

Methodology

• The study was conducted on five healthy adult horses. The pharmacokinetics, which is the process the drug undergoes in the body involving absorption, distribution, metabolism, and excretion, was evaluated using model-independent methods.

Findings

• Through intravenous administration, the researchers found that pentoxifylline was quickly cleared from the horses’ systems with a mean residence time of approximately 1.09 hours. It had a large volume of distribution and high clear rate.
• However, oral absorption of pentoxifylline showed significant variations across the individual horses with peak concentration times ranging from 1-10 hours for either form of dosage (tablet or syrup).
• The relative bioavailability, which measures the amount of drug that reaches systemic circulation, was found to be almost identical between whole and crushed tablets. Therefore, the form of the orally administered drug doesn’t seem to alter its pharmacokinetics.
• Ratios of the areas under the pharmacokinetic curves for pentoxifylline and its alcohol metabolite were different when administered orally versus intravenously, indicating that the route of administration might affect how the drug is metabolized.

Conclusion

• Given the significant differences in how the drug is absorbed among individual horses and depending on the administration route, the study does not provide specific dosage or form recommendations for administering pentoxifylline to horses. The results underscore the need for further research to establish a consensus for appropriate dosing.