Bioequivalence Study of Two Oral Doxycycline Formulations (Doxysol® and Doxymed®) in Healthy Broiler Chickens

Aims: The present study was designed to assess the comparative bio-equivalence of Doxysol® and Doxymed® in healthy broiler chickens after oral administration of both products in a dose of 20 mg doxycycline/kg.b.wt. Materials and Methods: Twenty broiler chickens were divided into two groups. The first group was designed to study the pharmacokinetics of Doxysol, while the 2nd group was designed to study the pharmacokinetics of Doxymed. Each broiler chickens in both groups were injected intravenously with 20 mg doxycycline/kg.b.wt. Blood samples were obtained from the wing vein and collected immediately before and at 5, 15, 30 minute, 1, 2, 4, 6, 8, 12 and 24 hours after a single intravenous or oral administration. Results: Doxycycline in both products obeyed a two compartments open model following I.V. injection in a dose of 20 mg/kg.b.wt. The disposition kinetics of Doxysol® and Doxymed® following oral administration of 20 mg doxycycline base/kg.b.wt. revealed that the maximum blood concentration [Cmax.] were 4.70 and 4.65 μg/ml and attained at [tmax.] of 1.30 and 1.40 hours, respectively. Doxycycline in Doxysol® and Doxymed® was eliminated with half-lives [t0.5(β)] equal to 1.98 and 2.31 hours, respectively. The mean systemic bioavailability of doxycycline in Doxysol® and Doxymed® after oral administration in healthy chickens was 92.57 and 88.21%, respectively. Conclusion: Doxymed® is bioequivalent to Doxysol® since Cmax test/Cmax reference and AUCtest/AUCreference ratios were 99% and 90%, respectively.