Fluorometric and Microbiological Assays for Rifampicin and the Determination of Serum Levels in the Dog

Abstract

Rifampicin is oxidized with hydrogen peroxide to a product that is fluorescent in alkaline solutions. Maximum fluorescence is measured at 480 nm with an excitation wavelength of 370 nm. The lower limit of detection of rifampicin in water is 0.1 μg/ml. A microbiological assay with Staphylococcus aureus 560 as the assay organism verified the reliability of the fluorometric assay. The fluorametric and microbiological assays were applied to the estimation of rifampicin in serum and were used to obtain concentration-time data for dogs that had been treated orally with 10 mg/kg rifampicin. Half-life of rifampicin in the dog was 8 h.