Quantitative HPLC-UV method for the determination of firocoxib from horse and dog plasma.

The research article summarises the development of a sensitive high-performance liquid chromatography-ultraviolet (HPLC-UV) method to measure levels of firocoxib, a selective COX-2 inhibitor, in horse and dog plasma.

Methodology

• The researchers developed a reversed-phase HPLC-UV method to determine the quantity of firocoxib, a specific COX-2 inhibitor, in plasma samples.
• This method starts by mixing a 1.0 mL sample of dog or horse plasma with water. This mixture is then passed through a hydrophobic-lipophilic copolymer solid-phase extraction column, which helps in isolating firocoxib from the other components present in the plasma.
• Quantitation of firocoxib is determined by comparing to an external standard curve.

Validation and Results

• The method developed was validated and it showed to have a limit of quantitation of 25 ng/mL and a detection limit of 10 ng/mL. These parameters define the smallest amount of firocoxib that can be measured quantitatively and detected, respectively.
• The validated upper limit of quantitation, representing the largest quantity of firocoxib that could be accurately measured using this method, was found to be 2500 ng/mL for horses and 10,000 ng/mL for dogs.
• The average recoveries of firocoxib from the plasma samples were high, ranging from 88-93% for horse plasma and 96-103% for dog plasma, indicating that the method is efficient in extracting and determining firocoxib.
• The coefficient of variation for all measurements was less than 10%, suggesting that the method provides consistent results.

Conclusion

• Given the validation results, the HPLC-UV method developed for the determination of firocoxib in plasma samples is thought to be suitable for analyzing clinical samples from pharmacokinetic and bioequivalence studies and drug monitoring.
• This allows for better understanding of firocoxib behaviour within the body, its pharmacokinetics, and can also aid in monitoring the drug levels in dogs and horses, making it a valuable tool in veterinary medicine.