Pharmacokinetics of Gentamicin C after IV, IM, SC and Oral Administration , C , C 1 1a and C 2 in Broiler Chickens 2a

Abstract

The pharmacokinetics and bioavailability of four major gentamicin components (C 1 , C 1a , C 2 and C 2a ) in chicken plasma administered at 5 mg/kg body weight by different routes of administration (IV, IM, SC and oral) was determined using reversed-phase high performance liquid chromatography (RP-HPLC) and pre-column derivatization with Phenylisocyanate (PIC). All the components, except for C 1a were well absorbed (bioavailability of 60% or greater) following administration by the IM and SC routes. The bioavailability of C 1a was 58% and 35% following IM and SC administration, respectively. The apparent volume of distribution (V ss and Vd area ) for the C 1 component was significantly smaller than for any of the other components individually or combined. In addition, the C 1 component had a significantly shorter t½β and MRT following intravenous administration and a higher C max /Dose following intramuscular administration. This study showed significant differences in some pharmacokinetics parameters between four gentamicin components (C 1a , C 2a , C 1 and C 2 ) after administration of single mixture of gentamicin by different routes in chickens. The differences may have clinical and toxicological implications, and could explain the high variation in total gentamicin pharmacokinetics.