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

Abstract

Aims: The present study was designed to assess the comparative bio-equivalence of Doxysol &reg and Doxymed &reg 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 &reg and Doxymed &reg following oral administration of 20 mg doxycycline base/kg.b.wt. revealed that the maximum blood concentration [ C max .] were 4.70 and 4.65 μg/ml and attained at [ t max .] of 1.30 and 1.40 hours, respectively. Doxycycline in Doxysol &reg and Doxymed &reg was eliminated with half-lives [ t 0.5 (β) ] equal to 1.98 and 2.31 hours, respectively. The mean systemic bioavailability of doxycycline in Doxysol &reg and Doxymed &reg after oral administration in healthy chickens was 92.57 and 88.21%, respectively. Conclusion: Doxymed &reg is bioequivalent to Doxysol &reg since C max test / C max reference and AUC test / AUC reference ratios were 99% and 90%, respectively.