Comprehensive analysis of Aspirin and Apixaban: thedevelopment, validation, and forced degradation studies of bulk drugs and in-house capsule formulations using the RP-HPLC method.

Objectives: This study aimed to develop a robust Reverse Phase-High-Performance Liquid Chromatography (RP-HPLC) method for simultaneous determination of Aspirin (ASP) and Apixaban (API) in bulk and in-house capsule formulations.

Methods: The separation was conducted on a Phenomenex Luna C₁₈ column using a Shimadzu LC20AT High-performance liquid chromatography (HPLC) system. The mobile phase consisted of 40:60 Acetonitrile (ACN): phosphate buffer (pH 4) modified by O-Phosphoric Acid (OPA). The parameters included a flow rate of 1 ml/min, a column temperature of 30°C, and Ultra-Violet (UV) detection at 227 nm. Method validation encompassed linearity, precision (Intraday and Interday), accuracy (% Recovery), and sensitivity (Limit of Detection (LOD) and Limit of Quantification (LOQ)). Stability testing followed The International Council for Harmonization (ICH) guidelines.

Results: The developed method demonstrated reliable separation of Aspirin and Apixaban with retention times of 5.37 min and 7.10 min, respectively. It exhibited linearity over the concentration ranges of 50-300 μg/mL for Aspirin and 5-15 μg/mL for Apixaban. The recovery percentage ranged from 90.02% to 101% for Aspirin and 98.18% to 101.18% for Apixaban. LOD and LOQ were determined as 0.84 μg/mL and 2.55 μg/mL for Aspirin, and 0.41 μg/mL and 1.24 μg/mL for Apixaban, respectively. Stability testing confirmed the method's robustness under various stress conditions.

Conclusions: The validated RP-HPLC method offers a reliable tool for routine analysis of Aspirin and Apixaban in pharmaceutical formulations, highlighting its potential for combined dosage applications and routine quality control.