Stability-indicating (liquid chromatographic) LC method for the determination of rifabutin in bulk drug and in pharmaceutical dosage form

A novel stability-indicating LC assay method was developed and validated for quantitative determination of Rifabutin in bulk drugs and in pharmaceutical dosage form in the presence of degradation products generated from forced degradation studies. An isocratic, reversed phase LC method was developed to separate the drug from the degradation products, using an Ace5-C18 (250 x 4.6 mm, 5 mu m) column, and 50 mM ammonium acetate (pH-4 by acetic acid) and acetonitrile (50: 50v/v) as a mobile phase. The detection was carried out at the wavelength of 275 nm. The Rifabutin was subjected to stress conditions of hydrolysis (acid, base), oxidation, photolysis and thermal degradation. Degradation was observed for Rifabutin hydrolysis (acid, base), oxidation and photolysis conditions attempted. There is no degradation in thermal condition. The degradation products were well resolved from the main peak. The percentage recovery of Rifabutin ranged from (99.42 to 100.27%) in pharmaceutical dosage form. The developed method was validated with respect to linearity, accuracy (recovery), precision, specificity and robustness. The forced degradation studies prove the stability-indicating power of the method.