Evaluation of the quality of compound liquorice tablets by DSC and HPLC fingerprints assisted with dissolution

A systematic quantitative fingerprint method (SQFM) was applied to evaluate the quality of compound liquorice tablets (CPLTs) in this paper. The method contained three main parameters: macroscopic qualitative similarity (S_m), macro quantitative similarity (P_m) and a leveling variance coefficient (α), which were used to analyze the similarity of curves and evaluate the fingerprints of CPLTs. Firstly, Differential Scanning Calorimetry (DSC) was applied to analyze CPLTs and the active raw materials (RMs). At the same time, the change of appearance and weight during DSC testing revealed that the two main thermal processes of CPLTs were between 240-320 °C and 400-500 °C. The DSC fingerprint (DSC-FP) of 49 batches of CPLTs was collected and the enthalpy values were calculated. Then, we studied the dissolution of CPLTs, collected ultraviolet fingerprints (UV-FP) and the P_m was used to plot the dissolution curve. The results showed that the dissolution and enthalpy had a negative correlation, and the formula was y= -32.38x+3207.49 with r= -0.83. Finally, the High Performance Liquid Chromatography fingerprint (HPLC-FP) of 49 batches of CPLTs was collected and assessed by SQFM. The results of quality evaluation of CPLTs by HPLC-FP combined with DSC-FP showed that 49 batches were divided into 4 levels, which could evaluate the quality of the drug more comprehensively and objectively.