The Complete Analysis of the Distribution Kinetics of the Oxytetracycline Antibiotic in the Exoskeleton of Farmed Pacific White Shrimp, Litopenaeus vannamei.

Oxytetracycline ( OTC) in shrimp shells may be dispersed to the environment as shrimp shred old cuticle in growout ponds. The study aims to assess the kinetics of OTC accumulated in shrimp shell. Sub-adult male Litopenaeus vannamei in the C- D₀ molting stage, were force fed with medicated feeds at various accurate dose levels that included 50, 500 and 1000 mg/kg-body weight ( BW). In addition to hemolymph, hepatopancreas and muscle were serially collected for 50 mg/kg- BW-dose group while cuticle was sampled for higher dose levels. All were assayed for OTC by a validated high-performance liquid chromatography ( HPLC) method. Mineral contents in shell samples of 500 mg/kg- BW-dose were also determined. The bioavailability markedly decreased with increasing dose due to incomplete dissolution and/or mild dysfunction in absorption. Administered doses, 2.69 and 2.25%, ended up in the shell after dosing with 500 and 1000 mg/kg- BW, respectively. OTC data after a dose of 50 mg/kg- BW was fitted into a three-compartment model with an added shell compartment with r² of 0.9920. The model was successfully extrapolated to predict OTC distribution in shell at higher doses. In addition, there was evidence that OTC may disturb the biomineralization process via complex formation with calcium and magnesium lowering the exoskeleton mineral contents. [ABSTRACT FROM AUTHOR]