Endometrial concentrations of ampicillin in mares after intrauterine infusion of the drug.

The research sought to measure how much of the penicillin-based antibiotic, ampicillin, was detectable in horse blood and the mucous membrane of the uterus after administration. More of the drug was found in mares in a particular phase of their reproductive cycle, except for just before biopsy. Despite this, the drug was found in the membrane hours after administration in both stages of reproduction.

Research Methodology

• The study revolved around a semi-synthetic penicillin, ampicillin, and its presence in the blood and endometrial systems of mares post-administration. The ampicillin was administered via intrauterine infusion.
• Researchers focused on concentrations of ampicillin in the blood over periods of up to 24 hours following a 3g infusion and took blood samples on four different occasions within this timeframe.
• Additional endometrial biopsy specimens were obtained at the end of the 24-four hour period to measure and compare the amount of ampicillin present in the uterus.

Findings and Analysis

• The research showed that more ampicillin was measurable in mares during their diestrous phase, a phase of their reproductive cycle when they are not in the heat, except for the sample taken just before the 24-hour biopsy.
• Intriguingly, none of the pre-biopsy serum samples showed any presence of ampicillin, however, ampicillin was detected in the serum of 4 out of 5 mares that were in their diestrous phase after the endometrial biopsy was taken.
• It worth noting that, all 24-hour biopsy specimens had ampicillin concentrations greater than the minimum inhibitory concentration, which is the smallest concentration of drug that visibly inhibits growth. This was regardless of their reproductive cycle stage.

Conclusion

• This research demonstrated how traces of ampicillin remained detectable in the blood and endometrial systems of mares long after intrauterine infusion. The stage of the reproductive cycle appeared to influence the concentration of the drug in the bloodstream, but not in the endometrium.