Abstract

BIO-EQUIVALENCE STUDY OF ORAL TYLOSIN-DOXYCYCLINE FORMULATIONS (STANDARD TYLOSIN-DOXYCYCLINE AND COLITHROPRIM®) IN BROILER CHICKENS

Ashraf Elkomy* and Mohamed Aboubakr

ABSTRACT

The present study was designed to assess the comparative bio-equivalence of Standard tylosin-doxycycline combination and Colithroprim® in healthy broiler chickens after oral administration of both products in a dose of 10 mg tylosin base and 12.5 mg of doxycycline base/kg.b.wt. Twenty four broiler chickens were divided equally into two groups (12 chickens for each group). The first group was designed to study the pharmacokinetics of Standard tylosin-doxycycline combination, while the 2nd group was designed to study the pharmacokinetics of Colithroprim®. Each broiler chicken in both groups was orally administered with 10 mg tylosin base and 12.5 mg of doxycycline base/kg.b.wt. Blood samples were obtained from the wing vein and collected immediately before and at 0.08, 0.16, 0.25, 0.5, 1, 2, 4, 6, 8, 12 and 24 hours after a single oral administration. The disposition kinetics of tylosin in Standard tylosin-doxycycline combination and Colithroprim® following oral administration of 10 mg tylosin base and 12.5 mg of doxycycline base/kg.b.wt, revealed that the maximum blood concentration [Cmax] were 3.17 and 3.08 μg/ml and attained at [tmax] of 1.01 and 1.02 hours for both products, respectively. The disposition kinetics of doxycycline in Standard tylosin-doxycycline combination and Colithroprim® following oral administration of 10 mg tylosin base and 12.5 mg of doxycycline base/kg.b.wt, revealed that the maximum blood concentration [Cmax] were 4.21 and 3.95 μg/ml and attained at [tmax] of 1.02 and 1.13 hours for both products, respectively. In conclusion: Colithroprim® is bioequivalent to Standard tylosin-doxycycline combination, since tylosin ratios of Cmax, AUC0-24 and AUC0-∞ (T/R) were 0.97, 0.94 and 0.93 respectively, and doxycycline ratios of Cmax, AUC0-24 and AUC0-∞ (T/R) were 0.94, 0.94 and 0.93 respectively. These are within the Bio-equivalence acceptance range. Standard tylosin-doxycycline combination and Colithroprim® are therefore bioequivalent and interchangeable.

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