Chromatographic Method for Simultaneous Determination of Triamcinolone Acetonide and Triethyl Citrate in Polymeric and Biological Matrices

Hot-melt extrusion (HME) is widely used in pharmaceutical manufacturing; however, reliable analytical tools are required to simultaneously monitor drug content and excipient stability under thermal processing. In this study, a selective and robust HPLC–UV method was developed and validated for the concurrent determination of triamcinolone acetonide (TA) and triethyl citrate (TEC) in HME polymeric films and porcine buccal mucosa. Chromatographic separation was achieved on a C18 column using an acetonitrile–water mobile phase (30:70, v/v) at a flow rate of 0.6 mL min−1, with detection at 240 nm for TA and 210 nm for TEC. The method was validated for selectivity, linearity, precision, and accuracy, including selectivity assessment in the presence of mucosal extract and polymeric matrix components, and recovery of TA in porcine buccal mucosa. Excellent linearity was obtained over 0.20–12.5 µg mL−1 for TA and 4.5–30.0 µg mL−1 for TEC (r ≥ 0.998), with precision below 6.3% and TA recovery exceeding 94%. Application to extruded films confirmed uniform analyte distribution and enabled simultaneous monitoring of TA degradation and TEC loss under thermal stress. These results demonstrate that the proposed method is suitable for formulation development, process monitoring, and stability assessment of HME-based pharmaceutical systems.