Pharmacokinetics and Bioequivalence of Doxycycline (Providox^® and Doxyvet 0-50 S^®) Oral Powder Formulations in Chickens

A bioequivalence and pharmacokinetics profiles of two doxycycline powder formulations (Providox^® and Doxyvet 0-50 S^®) were compared in 24 healthy chickens following administration of a single oral dose (20 mg/kg bw). Serial blood samples were drawn at 10 points after administration to determine doxycycline concentrations in chicken plasma by HPLC/UV. the pharmacokinetics parameters; area under plasma concentration-time curve (AUC_0-24), maximum plasma concentration (C_max) were determined for both formulations. The average means of AUC_0-24 and C_max for Providox^® and Doxyvet 0-50 S^® were very close (62.32 ± 3.34 and 57.55 ± 4.66 µg.h/ml and 5.36 ± 0.26 and 5.08 ± 0.25 µg/ml, respectively) with no significant differences based on ANOVA. The 90% confidence intervals of the parameters AUC_0-24 and C_max between two formulations were within the range 80 to 125 % of bioequivalence according to US FDA regulation. The relative bioavailability of Providox^® compared to Doxyvet 0-50 S^® was 108.24%. Therefore, the Providox^® and Doxyvet 0 - 50 S^® were considered to be bioequivalent.