Simultaneous Determination of Doxycycline Hyclate and Fusidic Acid by RP-HPLC in Bulk and Microemulsion Formulation

SUMMARY. For separation and simultaneous quantification of more than one analyte in pharmaceutical dosage forms required sensitive and reproducible chromatography based analytical methods. A method for simultaneous quantification of doxycycline hyclate (DH) and fusidic acid (FA) using high performance liq-uid chromatography was developed. The mobile phase was combination of acetonitrile, 0.010 M oxalic acid and methanol (34:36:30 %v/v) in isocratic mode with C8 analytical column (4.6 mm, 150 mm, 3.5 µm). The developed method was validated against ICH guidelines for establishing the linearity, LOD, LOQ, accuracy and precision along with system suitability testing. Percentage recovery of DH was found to be 101.66% and 102.66% for FA respectively in microemulsion formulation. The calibration range was 125 to 1500 µg/ mL with a co-efficient correlation (r² > 0.999). Intermediate precision was found to be 1.18% and 1.05% and accuracy in termed of % recovery was between 95%-105% for DH and FA, respectively. An accurate and precise method was successfully developed and validated for reliable simultaneous quantification of DH and FA and may be implemented for routine analysis of both DH and FA in topical formulation. DH and FA had undergone through stress degradation studies by continuous exposure with acid, alkali, hydrogen peroxide (oxidative), heat and U.V. light degradation studies.