Development and Validation of Liquid Chromatography Method for the Determination and Quantification of Impurities in Imiquimod

New stability indicating reverse phase high performance liquid chromatography (HPLC) method is developed for the determination of Imiquimod and its impurities. Separation is achieved on a C18 column (Inertsil-ODS3 4.6 × 250 mm, 5  µm) using gradient elution mode with mobile phase-A having disodium hydrogen phosphate buffer (10 mM) with 0.1% v/v triethyl amine and pH adjusted to 6.0 with ortho-phosphoric acid while mobile phase-B consist of an equal mixture of methanol and acetonitrile. The flow rate was optimized to 1.2 mL/min and column oven temperature 30°C. Detection was carried out at wavelength 226 nm. This developed method is then validated as per International Council for Harmonisation (ICH) guideline and found out to be linear, accurate, specific, selective, precise, and robust. The drug is also subjected to forced degradation using stress conditions of acid-base hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found out only in harsh condition of oxidative degradation where degradation impurity is also predicted. All degradation products were well separated. Test solution was found to be stable for 24 hrs. The method can be successfully applied for the determination of Imiquimod and its impurities in routine and stability samples.