Study of doxofylline and its degradation products in bulk drug by a newly developed stability-indicating HPLC method.

The purpose of this work was to study the stability behavior of doxofylline under different stress conditions and to develop a sensitive stability-indicating HPLC assay method. The stress conditions applied included heat, moisture, acid-base hydrolysis, oxidation, and UV light. The drug was particularly labile under oxidative and thermal stress conditions, with 58.40 and 53.90% degradation, respectively. Good resolution of drug from degradation products formed under stress conditions was achieved on a C18 column using 10 mM KH2PO4 buffer solution (pH 6) methanol (40 + 60, v/v) as the mobile phase (pH 7.2). The flow rate was 1 mLlmin, and the detection wavelength was 273 nm. The method was validated for linearity, range, precision, accuracy, LOD, and LOQ. The RSD was found to be <2%. Since the method effectively separates the drug from its degradation products, it can be used as a stability-indicating method.