To establish a flow-through cell method for determining the dissolution of tazarotene gel and analyze the correlation between its in vitro release behavior and microscopic characteristics.

A closed-loop flow-through cell system was employed to systematically investigate the effects of release medium composition, surfactant concentration, flow rate, filter membrane pore size, and fluid flow pattern on the in vitro release profile of tazarotene, while comparing the release behavior differences between commercial generic and originator products. Additionally, confocal laser micro-Raman imaging was utilized for non-destructive characterization of critical microstructure parameters including API polymorphic form and particle size distribution in both formulations, followed by analysis of key quality attributes contributing to the observed in vitro release performance disparities.

The dissolution curve with a suitable degree of distinction can be obtained by using 0.9% sodium chloride solution containing 0.5% sodium dodecyl sulfate as dissolution medium, at (32±0.5) ℃ with a flow rate of 8 mL·min^-1 and a 100 μm filter membrane. Although the polymorphic form of the active pharmaceutical ingredient (API) in generic formulations was consistent with that of the originator product, the undissolved particle counts (54 particles·mm^-2) in the generic drugs was significantly higher compared to the originator product (25 particles·mm^-2), resulting in statistically significant differences in their in vitro release profiles.

The microstructural characteristics reflect differences in the types of key solubilizing agents used as excipients in the formulation, which may influence the in vitro release properties of the product. It is recommended that domestic manufacturers promptly optimize formulation processes and improve product quality.