Thiazides I. Limitations of Bratton-Marshall Colorimetric Assay Method and Its Modifications in the Determination of Chlorothiazide in Bioequivalency Studies

Abstract
The bioavailability of a commercially available 250 mg and a 500 mg chlorothiazide tablet was determined in human volunteers using cumulative urinary drug excretion. Urine specimens were analyzed for concentrations of chlorothiazide by four different modifications of the Bratton-Marshail assay procedure. Study results demonstrated that the estimation of this drug's bioavailability could vary with the particular modification used for urinary drug analysis.