Development and validation of a high-performance liquid chromatography method for the quantification of l-tetrahydropalmatine in extended-release tablets

Abstract

This study aimed to develop and validate a high-performance liquid chromatography (HPLC) method for quantification of l-tetrahydropalmatine (l-THP) in extended-release tablets used in an in vitro - in vivo correlation study. A reversed-phase C18 column (250×4.6 mm; 5 μm) was used with an injection volume of 20 μl and a total run time of 10 minutes. Various mobile phase compositions and flow rates were investigated, and the optimal mobile phase was a mixture of acetonitrile and 0.05 M phosphate buffer (pH 4.5) in a 30:70 ratio, with a flow rate of 1.5 ml/min. The method demonstrated a limit of detection (LOD) of 3.125 ng/ml and a limit of quantification (LOQ) of 12.5 ng/ml, with a linear calibration range from 10 to 100 μg/ml (R²=0.999). Validation was conducted in accordance with the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) Q2(R1) guidelines, confirming the method’s accuracy, precision, specificity, linearity, and sensitivity. The method was successfully applied to quantify l-THP in three extended-release tablet samples (FR, MR, SR), yielding measured drug contents of 105.25±0.73, 100.67±1.59, and 103.65±1.09%, respectively. This HPLC method can be used for quality control in the formulation and development of extended-release tablets containing l-THP.