Population pharmacokinetics of marbofloxacin in horses: preliminary analysis.

The research aims to investigate the factors affecting the population pharmacokinetics of marbofloxacin in both healthy and diseased horses. The study found that the health status of the horse significantly affects the systemic clearance of the drug.

Study Overview

• The research was conducted on two groups of horses, which includes 21 healthy and 16 diseased horses. The goal was to determine the population pharmacokinetics of marbofloxacin, which is the study of how an organism affects a drug and contributes to variability in drug response.

Methodology and Findings

• The researchers used mixed effects models to test demographic and physiological covariables along with the disease status of the horses.
• The results showed no significant correlation between the tested covariables and compartmental volumes or clearance of distribution.
• However, it was found that the clinical status of the horse significantly impacted the systemic clearance of the drug. In particular, clearance rates were lower, and variance was higher in diseased horses compared to healthy horses.
• This suggests that the dosing regimen needs to be carefully adjusted for diseased horses, particularly because variability of the Area Under the Curve (AUC) was greater in them.

Dosage Regimen Assessment

• Pharmacokinetics and pharmacodynamics are integrated to analyze the AUC/MIC ratio, which represents the efficacy of the drug.
• For the efficacy prediction, a lower ratio (below 60 hours) indicates poor efficacy. As per this, a dosage regimen of 2 mg/kg administered intravenously is inadequate for approximately 19% of the diseased horses if the MIC (Minimum Inhibitory Concentration) of the bacteria was 0.1 microg/mL.
• However, it was also found that 93% of diseased horses could achieve a ratio above 125 hours (predicting very good efficacy) for the MIC(90) of Enterobacteriaceae (0.027 microg/mL).
• These findings highlight the importance of understanding the health condition of an animal when deciding on dosage to optimize the drug’s efficacy and minimize potential adverse effects.