Labrasol mediated enhanced solubilization of natural hydrophobic drugs in Pluronic micelles: Physicochemical and in vitro release studies

• Solubilization of Quercetin and Curcumin in Pluronics and Pluronic-Labrasol mixed micelles was studied. • Pluronic-Labrasol mixed micelles showed enhanced drug loading than pure Pluronic micelles. • DPV and Fluorescence measurements demonstrated that drugs are solubilized within the micelles. • DLS measurements confirmed that the addition of Labrasol in Pluronics resulted in small sized micelles. • The in vitro release profile showed sustained release behaviour in both Pluronic and Pluronic-Labrasol mixed micelles. In present work, the solubilization of two natural hydrophobic drugs Quercetin (QCT) and Curcumin (CUR) has been systematically investigated in Pluronics (P84, F127, F68) and Pluronics-Labrasol mixed micelles. UV–Visible studies confirmed that the solubility, drug loading efficiency, partition coefficient (P), standard free energy of solubilization (ΔG ° ) of QCT and CUR were significantly higher in Pluronic P84 and P84-Labrasol mixed micelles than other investigated systems. Solubilization locus of both drugs in pluronic and Pluronic-Labrasol mixed micelles was scrutinized by employing DPV measurments. Enhanced solubilization of both drugs in Pluronic P84 and P84-Labrasol mixed micellar solution is also well supported by increased fluorescence intensity in respective fluorescence titrations. Inferences from Dynamic light scattering (DLS) studies revealed that the hydrodynamic diameter (D h ) of Pluronic-Labrasol mixed micelles is smaller than pure Pluronic micelles. Upon the inclusion of QCT and CUR, D h of both Pluronic and Pluronic-Labrasol mixed micelles was found to be increased . Pluronic and Pluronic-Labrasol mixed micellar formulations exhibited the sustained release behaviour for both QCT and CUR. The improved solubilization of QCT and CUR may serve as an efficient system for sustained drug delivery enabling enhanced oral absorption and bioavailability.