The detection and biotransformation of guanabenz in horses: a preliminary report.

This study explores the detection and changes in the antihypertensive drug Guanabenz when administered to horses. Using chromatography and mass spectrometry methods, the research found that it is possible to detect Guanabenz in horse serum.

Research Overview

• The research revolves around Guanabenz, a drug primarily used as an antihypertensive agent in humans. It has reportedly been administered to racing horses, which led to this study’s investigation into its quantification in horses’ serum and urine, and the changes it undergoes within the horse’s body.
• The findings from this research are of significant importance to the horse racing industry, as the detection of class 3 foreign substances such as Guanabenz can result in severe penalties for the horse’s trainer.

Research Methodology

• The study employed liquid chromatographic/tandem quadrupole mass spectrometric (LC-MS/MS) to detect Guanabenz in serum samples from horses treated with the drug via intravenous administration at varying dosages.
• The researchers adapted a method previously used in work with another drug named Clenbuterol to make this detection possible and analyzable.
• The researchers also tested urine samples after administering the drug to discover any metabolites of Guanabenz in the horses’ bodies.

Research Findings

• The study found that the Guanabenz parent compound could be detected in horse serum with an apparent limit of detection of approximately 0.03 ng/ml and a limit of quantitation of 0.2 ng/ml.
• Guanabenz concentrations in the serum peaked at around 100 ng/ml after a 0.2 mg/kg dose was administered, and the drug could still be detected up to eight hours post-administration of a 0.04 mg/kg dose.
• The testing of urine samples revealed evidence of at least one glucuronide metabolite, suggesting that Guanabenz undergoes biotransformation within the horse’s body.

Conclusion

• Through the research findings, the study has paved the way for developing a confirmatory test for the presence of Guanabenz in horse racing, which can potentially alleviate the industry’s concerns about illegal drug use and maintain ethical standards.