Meloxicam-loaded Phospholipid/solutol® HS15 Based Mixed Nanomicelles: Preparation, Characterization, and in vitro Antioxidant Activity

Background: Rheumatoid arthritis (RA) is a debilitating disease which results in joint destruction, mainly due to chronic inflammation and oxidative stress. Meloxicam (MLX) is a preferential cyclooxygenase-2 (COX-2) inhibitor with potential free radical scavenging activity. Mixed nanomicelles (NMs) of MLX can augment its antioxidant effects. Objective: The present study aims to prepare, characterize, and evaluate the in vitro antioxidant effects of MLX-loaded mixed nanomicelles (MLXNMs). Method: Conventional thin-film hydration method was employed to fabricate MLX-NMs. The formulations were characterized for particle size, zeta potential, entrapment efficiency (EE), and drug loading (DL). Additionally, the optimized formulation was characterized for small-angle neutron scattering (SANS), in vitro drug release, and morphology. MLX encapsulation in NMs was confirmed by Fourier Transform Infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), 1H nuclear magnetic resonance (NMR), and X-ray diffraction (XRD), studies. The cell uptake of sulforhodamine B (SRB)- labeled NMs was studied in RAW 264.7 cells. The in vitro antioxidant activity of optimized MLX-NMs was studied by different antioxidant assays. Results: The optimized MLX-NMs exhibited average size and zeta potential of 88 ± 42 nm and -47.4 ± 16.2 mV, respectively. The EE and DL of MLX were 94.13 ± 1.01 % and 4.20 ± 0.05 %, respectively. Morphology studies confirmed the oblate ellipsoidal shape of MLXNMs. The in vitro release study exhibited a biphasic release pattern. MLX encapsulation into the micelle core was confirmed by FTIR, DSC, 1H NMR, and XRD studies. Additionally, SRB-labeled NMs demonstrated efficient in vitro cell uptake in RAW 264.7 cells. Furthermore, in vitro antioxidant studies exhibited superior free radical scavenging activity of MLXNMs as compared to free MLX. Conclusion: The NMs potentiate the in vitro antioxidant effects of MLX. Keywords: Antioxidant, cell uptake, free radical, meloxicam, mixed nanomicelles, rheumatoid arthritis.