The non-sink dissolution measurements were performed in FaSSIF using the μDISS Profiler (Pion Inc., USA). Each channel was calibrated with its own standard curve prior to the experiment. For calibration, stock solutions were prepared using dimethyl sulfoxide containing either crystalline celecoxib alone or celecoxib (30 wt%) in PVP. The standard curves were established with 6-8 concentrations by sequentially adding 5 μL aliquots of the stock solution into 3 mL of FaSSIF maintained at 37 ± 1 °C and stirred at 800 rpm. The standard curve showed a linear correlation R 2 ≥ 0.99 over a range of 15-270 μg mL -1 . The dissolution and solubility of all compounds was determined in FaSSIF. The path lengths (2-20 mm) of the in situ UV probes were selected based on the drug solubility in the selected medium and the expected degree of supersaturation. When a high solubility was anticipated, the shorter probe length (5 mm) was used.