Pharmacokinetic, biochemical and tolerance studies on carprofen in the horse.

This study investigates the pharmacokinetics, tolerance and biochemistry of carprofen, a non-steroidal anti-inflammatory drug (NSAID), in Thoroughbred geldings and Shetland ponies, revealing its potential as a long-acting NSAID in horses.

Method of Study

• The drug carprofen, a type of NSAID, was administered to six horses (three Thoroughbred geldings and three Shetland ponies) to study not just its pharmacokinetic behaviour but also its tolerance.
• The drug was delivered via multiple routes: intravenous (iv), intramuscular (im), and oral.
• The administration of the drug was performed once a day, at a dose rate of 0.7 mg/kg for two consecutive weeks.

Findings

• The main findings reveal the principal pharmacokinetic attributes of carprofen in horses and ponies. The volume of distribution was 0.08 – 0.32 litres/kg (average ± se = 0.23 ± 0.04), the systemic clearance was 26.4 – 78.5 ml/min (average ± se = 44.9 ± 8.0), and the plasma elimination half-life was 14.5 – 31.4 hours (average ± se = 21.9 ± 2.3).
• The study didn’t find any indication of carprofen accumulation in plasma when administered orally for 14 days consecutively.
• Carprofen, based on the investigation, was found to be well-tolerated following intravenous and oral administration. Interestingly, intramuscular administration led to an increase in plasma creatine kinase levels, pointing to possible muscle cell damage.

Conclusion

• Based on the results, the study suggests carprofen as a long-acting NSAID for horses from a pharmacokinetic standpoint. This implies that the drug remains effective for a prolonged period following administration.
• The study further suggests that any of the three tested delivery methods (intravenous, intramuscular or oral) can be used to achieve high plasma concentrations of carprofen.