Lonidamine and related impurities: HPLC analysis, stability profile and degradation pathways

Abstract

A sensitive HPLC-DAD method for the simultaneous determination of the anticancer lonidamine and five potential impurities in pure powder and tablet dosage forms was developed and validated. The impurities comprised by-products from thermal and photodegradation and potential secondary products from the drug synthesis. The structure of the main drug impurity was elucidated with the aid of GC-MS chromatography. A good resolution of all the analytes was achieved on a Gemini C18 column using isocratic elution and DAD detection. The optimal mobile phase consisted of a mixture of methanol–phosphate buffer (pH 3) (80 : 20, v/v). At a flow rate of 1.5 ml min⁻¹, the total time of analysis was less than 15 min. The method was determined to be linear in the range of 10–200 μg ml⁻¹ for the quantitation of lonidamine and 0.5–50 μg ml⁻¹ for the related substances with a detection limit of 0.15 μg ml⁻¹ for the impurities. Percentage recoveries ranged from 97.4 to 102.3 and 95.7 to 103.5 for the drug and impurities, respectively, and the relative precision values were less than 3.3%. Finally, the method was demonstrated to be robust, resistant to small variations of chromatographic variables such as pH, mobile phase organic/aqueous composition and column temperature.