Pharmacokinetics and tissue residue profiles of erythromycin in broiler chickens after different routes of administration
Goudah, A.; Abo El Sooud, K.; Abd El-Aty, A.M.
Deutsche Tierärztliche Wochenschrift 111(4): 162-165
2004
ISSN/ISBN: 0341-6593 PMID: 15171602 Document Number: 569449
This study investigated the disposition kinetics and plasma availability of erythromycin in broiler chickens after single intravenous (iv), intramuscular (im), subcutaneous (sc) and oral administrations (po) of 30 mg kg-1 erythromycin. Tissue residue profiles were also studied after multiple intramuscular, subcutaneous, and oral administrations of 30 mg kg-1 twice daily for three consecutive days. Plasma and tissue concentrations of erythromycin were determined using microbiological assay methods with Micrococcus luteus as the test organism. Following intravenous injection, plasma concentration vs. time curves were best described by a two compartment open model. The decrease in plasma drug concentration was bi-exponential with half-lives of (t1/2 alpha ) 0.19 and (t1/2 beta ) 5.3 h for the distribution and elimination phases, respectively. After intramuscular, subcutaneous and oral administrations of erythromycin at the same dose, the drug was detected in plasma after 10 min and reached its minimum level at 8 h post-administration. The peak plasma concentrations (Cmax) were 5.0, 5.3, and 6.9 micro g/ml-1 and were attained at 1.7, 1.4, and 1.3 h (Tmax), respectively. The elimination half-lives (T1/2el) were 3.9, 2.6, and 4.1 h and the mean residence times (MRT) were 3.5, 3.2, and 3.6 h, respectively. The systemic bioavailabilities were 92.5, 68.8, and 109.3%, respectively. In vitro protein binding of erythromycin in broiler plasma ranged from 21 to 31%. The limit of quantification (LOQ) for the assay was 0.03 micro g/ml-1 in plasma and tissues. The tissue level concentrations were highest in the liver and decreased in value in the following order: plasma > kidney > lung > muscle and heart. No erythromycin residues were detected in tissues and plasma after 24 h except in liver and kidney where it persisted for 48 h following intramuscular and oral administrations.