Development and Characterization of EGCG-Loaded TPGS/Poloxamer 407 Micelles with Evaluation of In Vitro Drug Release and In Vivo Pharmacokinetics and Tolerability Observations Following Oral Administration

Background: Epigallocatechin-3-gallate (EGCG), a potent green tea polyphenol, possesses significant therapeutic potential, but its clinical application is limited by poor gastrointestinal stability and low oral bioavailability. To address this, a novel herbal nanomedicine-based delivery system was developed utilizing D-α-tocopheryl polyethylene glycol succinate (TPGS) and Poloxamer 407. Objectives: This study aims to develop and characterize EGCG-loaded TPGS/Poloxamer 407 micelles, evaluating their physicochemical properties, storage stability, in vitro drug release profile, in vivo oral bioavailability, and preliminary tolerability observation. Methods: The micelles were prepared using the film hydration method followed by lyophilization. Results: The optimized 2:2 TPGS-to-poloxamer 407 weight ratio yielded EGCG-loaded micelles, displaying a mean particle size of 15.4 nm, a polydispersity index (PDI) of 0.16, a zeta potential of -17.7 mV, an encapsulation efficiency of 82.7%, and a drug loading capacity of 7.6%. The critical micelle concentration (CMC) was determined to be 0.00125% w/v. Transmission electron microscopy (TEM) confirmed the micelles' uniform spherical morphology. In vitro release studies demonstrated a sustained release profile in both simulated gastric and intestinal fluids. EGCG formulation remained stable for at least six months when stored at 4 °C. No adverse clinical signs were noted during the 28-day tolerability observation. In vivo pharmacokinetic evaluation in mice revealed a significant elevation in oral bioavailability, achieving a 2.27-fold increase in area under the curve (AUC) and a 1.8-fold increase in peak plasma concentration (Cmax) compared to free EGCG. Conclusions: Collectively, these findings underscore the potential of the TPGS/poloxamer 407-based micelle system as a promising oral delivery platform for EGCG, enhancing its stability and pharmacokinetic performance.