Development and Optimization of Puerarin-loaded in situ liquid crystal gels for ocular delivery in dry eye disease

Objectives: To design and optimize puerarin-loaded LCGs for controlled ocular delivery in DED, elucidating the drawbacks inherent to conventional ophthalmic vehicles regarding corneal bioavailability and precorneal elimination. Methods: Nine different formulations (PF1–PF9) were developed via a modified fusion-vortex method where glyceryl monooleate (GMO) and Soluplus® were used as independent variables in a 3 ² full factorial design. The formulations were examined for physicochemical characteristics, drug release kinetics, ex vivo corneal permeation, ocular irritation (HET-CAM), cytotoxicity (MTT assay in HCE-T cells), and stability according to ICH Q1A(R2) guidelines. Results: The optimization was carried out by the desirability function approach using Design Expert® v.13. Acceptable pH (7.14–7.26), drug content (96.4–98.6%) and entrapment efficiency (82.3–94.3%) were achieved by all the formulations. Corneal permeation and viscosity were well described by quadratic (R ² adj = 0.9977) and linear models (R ² adj = 0.9954), respectively. The optimum formulation PF6 (GMO 60% w/w, Soluplus® 15% w/w) possessed the highest desirability (D = 1), cumulative corneal permeation of 76.4 ± 2.43% in 8 hours with flux of 52.34 ± 1.78 μg/cm ² /h and precursor viscosity of 121.4 ± 3.7 mPa·s with non-Fickian anomalous transport qualified as the best fit for drug release profile (R ² = 0.9997). HET-CAM non-irritant classification was confirmed (IS = 0.38 ± 0.04), and IC ₅₀ of PF6 (182.4 ± 4.1 µg/mL) was greater than free puerarin (148.6 ± 3.2 µg/mL). Less than 3.5% variation was found in the stability studies over three months. Conclusion: PF6 exhibited superior corneal permeation, prolonged release, and good ocular safety, indicating its potential as a viable candidate therapeutic platform for DED treatment worth further in vivo validation.