Pharmacokinetics and bioequivalence of two suxibuzone oral dosage forms in horses.

This research study explores the pharmacokinetics (movement of drugs within the body) and bioequivalence (comparative effectiveness) of two oral dosage forms of suxibuzone in horses. The study concluded that both forms are equivalent in their effectiveness, and the paste variant shows slightly better bioavailability.

Research Objective & Methodology

• The objective of the research was to determine the pharmacokinetics and bioequivalence of two oral suxibuzone formulations – granulated and paste – in horses.
• Suxibuzone is a nonsteroidal anti-inflammatory drug given to alleviate pain and inflammation in horses. It was administered at a dosage of 19mg/kg to six horses through oral intake, following a two-period cross-over design.
• The study aimed to analyse blood and synovial fluid (found in the cavities of joints) samples from the horses for concentrations of Suxibuzone (SBZ) and its two main metabolites, Phenylbutazone (PBZ) and Oxyphenbutazone (OPBZ). These compounds are observed as SBZ rapidly changes into them.
• The concentrations were measured by high-performance liquid chromatographic technique, known for its sensitivity and specificity.

Research Findings

• The drug suxibuzone could not be detected in blood or synovial fluid samples from horses, indicating its high conversion rate into metabolites, PBZ and OPBZ.
• These metabolites were detected between 30 minutes and 72 hours after administration of both the granulated and paste form of the medicine. The average plasma concentration of PBZ peaked at five-seven hours after administration.
• Additionally, the area under the concentration-time curve (AUC – a critical measure in pharmacokinetics) for PBZ post-administration of granulated and paste dosage forms were found to be similar, indicating equal effectiveness.
• The average plasma concentration of OPBZ rose to 5-6.7 micrograms/mL, with the highest concentration detected between nine and twelve hours after taking either formulation. The respective AUCs for OPBZ were also alike, reaffirming the bioequivalence of the two dosage forms.

Conclusion

• The study concluded that the two forms of suxibuzone are bioequivalent in terms of their transformation to PBZ. For OPBZ, the confidence intervals of the pharmacokinetic parameters fell within the acceptable range, suggesting equivalent effectiveness.
• Also, the paste form provided slightly better bioavailability (extent and rate at which the active drug is absorbed and becomes available at the site of drug action) for both PBZ and OPBZ, indicating that it is marginally more efficiently absorbed by the body.