Stability-Indicating Method Development and Forced Degradation Studies Using LC-MS/MS for the Simultaneous Quantification of Atorvastatin Calcium and Ezetimibe in Fixed-Dose Combination Tablets Under ICH Guidelines

Venkatesh, Pooja Agarwal, Karthik Reddy

School of Pharmacy, Manipal College of Pharmaceutical Sciences, Manipal, India

Abstract

Fixed-dose combination (FDC) formulations that include atorvastatin calcium (ATV) and ezetimibe (EZE) are commonly used to treat hyperlipidemia and reduce cardiovascular risk. To ensure these formulations are of high quality, safe, and effective, it is crucial to employ robust analytical methods that can precisely measure both active pharmaceutical ingredients (APIs) and their degradation products within complex matrices. Stability-indicating analytical methods play a vital role in pharmaceutical development, quality control, and meeting regulatory standards, especially under the guidelines set by the International Council for Harmonisation (ICH). This research article is centered on the creation and validation of a sensitive, selective, and stability-indicating liquid chromatography–tandem mass spectrometry (LC-MS/MS) method for the concurrent quantification of atorvastatin calcium and ezetimibe in fixed-dose combination tablets. Additionally, extensive forced degradation studies were conducted to understand degradation behavior under various stress conditions, such as acidic, alkaline, oxidative, thermal, photolytic, and hydrolytic environments, as recommended by ICH Q1A(R2) guidelines. Chromatographic separation was accomplished using a reverse-phase C18 column with a gradient elution comprising an aqueous buffer (with formic acid) and acetonitrile. Detection was carried out using electrospray ionization (ESI) in both positive and negative ion modes, with multiple reaction monitoring (MRM) transitions specific to each analyte. The method underwent validation according to ICH Q2(R1) parameters, which include specificity, linearity, precision, accuracy, robustness, limit of detection (LOD), and limit of quantification (LOQ). Forced degradation studies indicated that atorvastatin is prone to degradation under acidic, oxidative, thermal, and photolytic conditions, while ezetimibe showed significant degradation under acidic, basic, and oxidative stress, aligning with previous findings on the stability profiles of the individual drugs. The developed LC-MS/MS method effectively resolved both drugs and their degradation products, demonstrating excellent peak purity and mass balance, thus confirming its stability-indicating capability. The validated method is appropriate for routine quality control, stability testing, and regulatory submissions for fixed-dose combination formulations of atorvastatin calcium and ezetimibe.

Keywords

Atorvastatin calcium; Ezetimibe; LC-MS/MS; Stability-indicating technique; Induced degradation; ICH guidelines; Method validation; Fixed-dose combination tablets; Pharmaceutical analysis; Degradation kinetics