In Vitro Drug Release Evaluation of RDV-Loaded Thermogel and Cyclodextrin

RDV-loaded cyclodextrin inclusion complex was prepared as a control before the drug release study. Literature methods were followed as references [21 (link),22 (link)]. The in vitro release profiles of RDV from the thermogels and cyclodextrin inclusion complexes were measured in Meilubio artificial tears (Dalian, China) at 35 °C. Briefly, 200 μL of RDV-loaded thermogel and cyclodextrin inclusion compound (both 1 mg/mL) were sealed into an MD25-3.5 dialysis membrane. Then, 2 mL of artificial tears was used as release medium. At predetermined time points, 1 mL of release medium was extracted, and 1 mL of artificial tears was replenished to maintain the volume. Cumulative release (%) profile of RDV was calculated using the Agilent 1200 HPLC system (Agilent Poroshell 120 EC-C18, 4.6 × 150 mm i.d., 4 µm) with a mobile phase of 0.05% TFA in H₂O/acetonitrile (50:50 v/v) at 254 nm. The column temperature was 30 °C and the injection volume was set at 10 µL. The total run time was 31.0 min with a flow rate of 1.0 mL/min; the peak at around 18.5 min was assigned to RDV.