Equine Endometrial Tissue Concentration of Fluconazole Following Oral Administration

The objective of this study was to determine the plasma and endometrial tissue concentrations of orally administered fluconazole and to determine if these tissue levels surpassed the minimum inhibitory concentration (MIC) for Candida spp. organisms in the reproductive tract of the mare. Mares from study 1 (n = 9) were administered a single oral loading dose of 14 mg/kg fluconazole. Plasma and endometrial tissue samples were collected before fluconazole administration and for 24 hours after the loading dose. Study 2 mares (n = 3), a subset of study 1, were administered the loading dose, followed by maintenance doses of 5 mg/kg every 24 hours for 6 days. Plasma and biopsy samples were collected for 48 hours after the last maintenance dose. High pressure liquid chromatography-tandem mass spectrometry was used to determine the concentration of fluconazole in all samples. The mean plasma and endometrial fluconazole levels 24 hours after the loading dose were 9.53 ± 0.824 μg/mL (mean ± standard deviation) and 11.3 ± 2.38 μg/g, respectively. Fluconazole levels in plasma and endometrial tissue 24 hours after the last maintenance dose were 7.82 ± 1.81 μg/mL and 7.23 ± 3.86 μg/g, respectively. Oral fluconazole administered as a 14-mg/kg loading dose and a 5-mg/kg maintenance dose every 24 hours will result in endometrial tissue levels near the accepted MIC values for most Candida spp. and surpass the MIC for Candida albicans in the reproductive tract of the mare. Consequently, this dosage regimen could be considered for the treatment of infectious endometritis caused by susceptible fungal organisms of Candida spp. in the mare.