Development and validation of an HPLC method for quantification of solifenacin in spiked human breast milk

An efficient and reliable reversed phase high performance liquid chromatography (HPLC) method was established and validated for the quantitative analysis of solifenacin succinate in fortified human breast milk samples. Chromatographic separation was carried out on a C18 column (150 × 4.6 mm, 5 μm particle size) and a isocratic mobile phase composed of acetonitrile and phosphate buffer (pH 3.5) in a 65:35 (v/v) ratio. The flow rate was at 1.1 mL/min, and detection was performed at 225 nm using a ultraviolet (UV) detector. The method exhibited excellent linearity in the range of 1.0 to 40.0 ng/mL (r² = 0.9999). The validation process was performed in accordance with European Medicines Agency (EMA) bioanalytical guidelines, and included selectivity, accuracy, precision, sensitivity, recovery, robustness, and stability assessments. The liquid-liquid extraction (LLE) procedure used for sample pretreatment provided satisfactory recovery (mean: 99.32 %) and minimized matrix interferences from breast milk. The method showed high reproducibility, did not require an internal standar, and offered a rapid analysis time of approximately 3.4 minutes. This study offers a simple, cost-effective, and sensitive HPLC-UV method for monitoring solifenacin levels in breast milk matrices, providing a valuable tool for evaluating drug safety during lactation.