BIOAVAILABILITY AND DISPOSITION KINETICS OF AMOXICILLIN

Abstract

OBJECTIVE: The study was planned to observe the bioavailability anddisposition kinetics of amoxicillin in adult rabbits (irrespective of sex) under healthy anddehydrated conditions. Design: Comparative. Place and duration of study: The study wasconducted at the department of pharmacology, University of Veterinary and Animal Sciences,Lahore from April 2013 to October 2013. Methodology: Initially all rabbits were weighed andtheir packed cell volume (PCV) and other biochemical parameters were observed under normalconditions. Bioavailability and disposition kinetics of amoxicillin (10mg/kg body weight) werestudied in normal rabbits following oral and intravenous route of drug administration. After 10days washout period, these rabbits were made dehydrated by keeping the animals off waterbut not food. The animals with 10% decrease in body weight were declared dehydrated. Theirparameters were again measured. Treated rabbits were administered amoxicillin orally andintravenously (10mg/kg body weight). Samples were drawn at prescribed time. Amoxicillinwas assessed in plasma by using microbiological assay method. Plasma concentration wasanalyzed using non compartmental method. Results: The water deprived or dehydrated rabbitsshowed a significant increase in the packed cell volume, blood glucose and plasma globulins ascompared to the normal rabbits. However, there was a significant (p<0.05 & p<0.01) decreasein body weight, total proteins, albumins and albumin globulin ratio of the dehydrated rabbits.The peak plasma concentration, volume of distribution and rate constant of elimination waslower in the dehydrated rabbits as compared to the normal rabbits. The plasma concentrationof amoxicillin after intravenous administration in dehydrated rabbits had a significant (p<0.05& p<0.01) larger area under curve, area under 1st moment curve, a longer half life and a largermean residence time. Conclusions: The study in the dehydrated rabbits indicated the need ofmodification of dosage regimen.