# Hematological and Biochemical Effects Associated with Prolonged Administration of the NSAID Firocoxib in Adult Healthy Horses

## TL;DR

This study examines the effects of long-term firocoxib use in horses and finds that while some blood changes occur, they return to normal after treatment stops.

## Contribution

The study provides preliminary evidence on the safety of prolonged firocoxib administration in horses.

## Key findings

- Some hematological and biochemical effects were observed during treatment but returned to baseline post-treatment.
- No clinically relevant adversities were observed during or after treatment.
- The results suggest a need for further studies with more comprehensive designs.

## Abstract

Non-steroidal anti-inflammatory drugs (NSAIDs) represent one of the most commonly used classes of drugs in both human and veterinary medicine. However, many clinical side effects have been observed, especially when treatment has been prolonged. While the anti-inflammatory efficacy and safety of repeated administration of firocoxib (Previcox®), which is a selective NSAID COX-2 inhibitor, has been evaluated for short-term use (one to fourteen days), its clinical relevance for longer-term use is not known. As a preliminary study, healthy, adult male and female horses (n = 7) were treated with daily oral firocoxib (0.11–0.14 mg/kg) for 40 days concomitant with the collection of blood samples encompassing treatment to assess hematological and biochemical endpoints. While this preliminary or pilot study was not without inherent limitations, treatment resulted in some hematological or biochemical effects that returned to pre-treatment or baseline values post-treatment without any clinically relevant adversity. Thus, the apparent favorable outcomes with the extended use of firocoxib provide a basis for future studies to reproduce these results with other more comprehensive study designs that may involve prolonged administration to healthy as well as injured or diseased horses to evaluate efficacy and the use of other clinically relevant endpoints.

Non-steroidal anti-inflammatory drugs (NSAIDs) represent one of the most commonly used classes of drugs in both human and veterinary medicine. However, many clinical side effects have been observed, especially when treatment has been prolonged. While the anti-inflammatory efficacy and safety of repeated administration of firocoxib (Previcox®), which is a selective NSAID COX-2 inhibitor, has been evaluated for short-term use (one to fourteen days), its clinical relevance for longer-term use is not known. As a preliminary study, healthy, adult male and female horses (n = 7) were treated with firocoxib for 40 days concomitant with the collection of blood samples encompassing treatment to assess hematological and biochemical endpoints. Daily oral administration of firocoxib was performed with one 57 mg tablet/animal (0.11–0.14 mg/kg), which was crushed and mixed with feed. Blood samples were collected one day before treatment (D0 or basal sample), during (D10, D20, D30, and D40), and after treatment (D55 and D70). Results indicated some hematological and biochemical effects were significantly reduced (p < 0.05) towards the end of treatment on D40 relative to pre-treatment or baseline values on D0. Post-treatment, all values returned to pre-treatment values within 30 days without any apparent clinical adversities. In conclusion, while these preliminary results are favorable for prolonged use of firocoxib in horses, future studies are required to evaluate the efficacy of prolonged use accompanied with other clinically relevant endpoints in healthy as well as injured or diseased animals.