Sodium oxacillin in the horse: serum, synovial fluid, peritoneal fluid, and urine concentrations after single-dose intramuscular administration.

Researchers administrated a single dose of sodium oxacillin to six healthy adult mares and tracked the concentrations of the drug in serum, synovial fluid, peritoneal fluid, and urine over a two-day period.

Methodology

• The research involved six healthy adult mares which were given a single dose of sodium oxacillin, measuring at 25 milligrams per kilogram of their body weight, administered intramuscularly (IM).
• Following the drug administration, the team conducted serial measurements over a 48-hour period, tracking the concentrations of sodium oxacillin in the mares’ serum, synovial fluid, peritoneal fluid, and urine.

Findings

• The mean peak serum oxacillin concentration reached 9.75 micrograms per milliliter half an hour after the injection.
• Concentrations of the drug in synovial and peritoneal fluids were also measured, with mean peak levels reaching 1.45 micrograms per milliliter and 2.60 micrograms per milliliter at 1 hour and 2 hours respectively.
• The concentrations of sodium oxacillin in all the three aforementioned fluids followed a similar pattern of decrease over the 48-hour period, becoming immeasurable by the end of the observation period.
• Urine concentrations of oxacillin were remarkably high compared to other fluids, with a mean peak concentration hitting 2,790.2 micrograms per milliliter in just half an hour post-injection.

Implications and Considerations

• This study presents valuable data on how sodium oxacillin behaves in the equine body upon intramuscular administration, showing a significant distribution across different body fluids and high levels of urinary excretion.
• The speedy decrease in oxacillin concentration across different body fluids needs to be considered when evaluating the efficacy and duration of action of this drug in horses.
• This research may help inform appropriate drug dosing and scheduling strategies for the use of sodium oxacillin in equine medicine, taking into account the fast metabolization and excretion rates seen in this study.