Analysis of gabapentin in equine plasma with measurement uncertainty estimation by liquid chromatography-tandem mass spectrometry.

The research article is about a new, sensitive method developed for analyzing gabapentin (GPT) in horse plasma using liquid chromatography-tandem mass spectrometry. This method will help in understanding the effects of GPT, an antiepileptic drug used for managing different kinds of pain in horses, and also aid in controlling its misuse in racehorses.

Introduction

• Gabapentin (GPT) is an antiepileptic drug used for managing neurotrophic pain and as an additive therapy for refractory partial seizures in humans.
• It is now being investigated for use in veterinary medicine for the treatment of laminitis, neuropathic, or chronic pain.
• Due to its availability from prescription and online sources, GPT can potentially be used in racehorses to disguise pain, necessitating a method to detect its presence in equine plasma.

Methodology

• The researchers developed a liquid chromatography-tandem mass spectrometry method for GPT analysis in equine plasma.
• Sample preparation involved quick protein precipitation with acetonitrile.
• The researchers achieved analyte separation on a reversed-phase ACE C(18) column and analyzed it using a hybrid triple-quadrupole linear ion trap mass spectrometer in positive electrospray ionization mode.

Results and Observations

• The limits of detection, quantification, and confirmation of GPT were found to be 1, 10, and 20 ng/mL, respectively.
• The calibration curve exhibited excellent linearity within the 10-2500 ng/mL range (r(2) > 0.999).
• Intra- and interday precision defined by coefficient of variation was less than 10%, indicating a high level of consistency in the measurements.
• Intra- and interday accuracy (bias %) ranged within 90-110%, affirming the reliability of the method.
• The estimation of measurement uncertainty was 8.6%, a relatively low value that adds to the validation of this new method.

Applications and Conclusions

• Satisfactory results from the test allowed the method to be used successfully for analyzing GPT in equine plasma in two instances: i) after GPT administration to research horses for pharmacokinetic studies, and ii) in routine forensic analysis in racehorses in Pennsylvania for doping control.