Body fluid concentrations and pharmacokinetics of chloramphenicol given to mares intravenously or by repeated gavage.

This research investigated the concentration and pharmacokinetics of chloramphenicol in a group of mares, given either intravenously or repeatedly via intragastric administration. The findings revealed that the absorption of the drug decreased with multiple intragastric doses resulting in lower drug concentrations.

Study Methodology and Measurement

• The study was carried out on 6 healthy mares which were administered chloramphenicol, either through a single IV administration (50 mg/kg of body weight) or repeated intragastric administrations (50 mg/kg every six hours).
• Additionally, the concentration of chloramphenicol in different body fluids (synovial fluid, peritoneal fluid, cerebrospinal fluid, and urine) were determined following the intragastric administrations.
• The elimination rate constant (K) values for the IV, the first intragastric dose, and the fifth intragastric dose were calculated and compared.
• Bioavailability after the intragastric administrations was also determined, along with the area under the curve (AUC) for all dosage types.

Study Findings

• The K values for the intravenous and intragastric administrations were not significantly different from each other, suggesting a consistent rate of elimination irrespective of administration method.
• However, the bioavailability of chloramphenicol decreased from 40% after the first intragastric administration to 21% following the fifth intragastric administration, indicating that the method of administration impacts how much of the drug becomes available for use in the body.
• The AUC values for the first and fifth intragastric dosages significantly differed from the IV dosage, with the AUC value for the fifth intragastric dosage also being distinct from the first intragastric dosage.
• Absorption of chloramphenicol was found to decrease with multiple intragastric administrations, leading to lower drug concentrations with subsequent doses.
• Finally, the study also found that repeated intragastric doses did not affect the absorption of xylose, a type of sugar, in the intestines.

Conclusion

The study highlighted that after multiple intragastric administrations, the amount of chloramphenicol absorbed in mares decreases, thereby leading to lower concentrations of the drug. Despite this, the study found no effect on the absorption of intestinal xylose. These findings may have implications for the method and frequency of administering this drug in veterinary medicine.