Development and Validation of a RP-HPLC Method for the Simultaneous Determination of Rifampicin and a Flavonoid Glycoside - A Novel Bioavailability Enhancer of Rifampicin

Purpose: To develop and validate a sensitive HPLC method for the separation and simultaneous estimation of two ingredients in a composition comprising of rifampicin and a flavonoid glycoside (an enhancer of oral bioavailability of rifampicin).
Methods: Reverse phase (RP) chromatographic separation and estimation was achieved using a Shimadzu HPLC system. RP-18 column was used at the following optimised conditions: mobile phase, acetonitrile:phosphate buffer, 50 mM, pH 5.0 in a ratio of 60:40 v/v; oven temperature, 40 °C; flow rate, 0.8 ml min^-1; detection wavelength, 340 nm; and total run time, 15 min.
Results: The developed method was validated in terms of linearity, range, accuracy, precision, limit of detection, limit of quantification, robustness and specificity. Good linearity was observed (r2 > 0.999) over the study range of both ingredients. The precision values for rifampicin and the flavonoid glycoside were in the range 1.08-2.77 and 1.14-2.98 %, respectively, while the limit of quantification was 0.10 and 0.05μg mL-1 respectively. The method was found to be robust and specific for both ingredients.
Conclusion: The developed method has a potential application in preclinical and clinical studies.

Keywords
Flavonoid glycoside; RP-HPLC; Rifampicin; Stability studies; Validation