A Novel Validated Stability-Indicating RP-HPLC Method for the Determination of Exemestane (Steroidal Aromatase Inhibitor)

Abstract

Background: Exemestane is an active irreversible lipophilic steroidal aromatase inhibitor used to treat breast cancer in addition to surgery and/or radiation in post-menopausal women. It is a white to slightly yellow crystalline powder with a molecular weight of 296.41. Exemestane is freely soluble in N, N-dimethyl formamide, soluble in methanol, and practically insoluble in water. The present robust RP-HPLC method supports the quantitative analysis of Exemestane in pharmaceutical formulations and for carrying out the forced degradation studies. Methods: A novel stability indicating liquid chromatographic method was developed for the determination of Exemestane using HPLC system of Shimadzu Model CBM-20A/20 Alite, equipped with SPD M20A prominence PDA and Zorbax SB C18 (150 mm × 4.6 mm i.d., 3.5 μm particle size) column. A mixture of sodium acetate buffer and acetonitrile (30:70, v/v) was used as a mobile phase with 1.0 ml/min flow rate and the method was validated as per ICH guidelines. Forced degradation studies were performed in different stress conditions such as acidic, basic, oxidation and thermal degradations. Results: The proposed liquid chromatographic method has shown linearity over a concentration range 0.1–200 μg/ml with regression equation y = 59411x - 7316 with correlation coefficient 0.999. During the validation process i.e. the intra-day and inter-day precision studies, accuracy and robustness studies the method has shown an RSD of less than 2.0 %. Exemestane is found to be more stable during all the degradation studies because the percentage of degradation was reported to be less than 10. Conclusions: The proposed method was found to be precise, accurate and robust and it can be applied for the determination of Exemestane in any formulations.