Byline: Mahmood Ahmad, Muhammad Iqbal, Naveed Akhtar, Ghulam Murtaza , Muhammad Asadullah Madni and Fatima Rasool – Email:[email protected] Abstract.- Diclofenac sodium and diclofenac potassium in tablet dosage form were tested for their bioavailability and disposition kinetics in a group of 18 rabbits in normal and Escherichia coli induced febrile condition with a washout period of 7 days. Biochemical and physiological parameters were measured in both normal and febrile state. Diclofenac levels in plasma were determined using a reversed-phase HPLC method. Primary kinetic parameters i.e. AUC0-8, Cmax, tmax and other disposition kinetics, were obtained with non-compartmental procedure. The values of physiological and biochemical parameter were significantly (p0.05) low in febrile rabbits as compared to that of normal animals.