Title : The Physicochemical, biopharmaceutical, and in vitro efficacy properties of diclofenac-loaded liposomes
Abstract:
Diclofenac-loaded liposomes were developed as a tool to treat inflammatory skin disorders. Topical administration of this molecule is a challenge that can be addressed by encapsulation into drug delivery systems. The aim of the current study was to develop, purify and optimize the process to obtain Small Unilamellar Vesicles (SUVs) of 50-100 nm liposomes drug delivery system for the local administration of diclofenac. The physicochemical properties of SUVs were characterized using dynamic light scattering (DLS) to measure particle size, Z-potential, polydispersity index (PDI), and nanoparticle concentration, while the encapsulation efficiency (%EE) was determined using HPLC-UV analysis, with a previous separation of free diclofenac from liposomes by centrifugation with ultrafiltration units. The in vitro permeation and release profiles were investigated with vertical diffusion Franz cells. Vesicles obtained (size, 86.43 ± 8.36 nm; polydispersity, 0.145 ± 0.026; Z-potential, -17.93 ± 0.42 mV) were able to encapsulate diclofenac with high yield (88.8 ± 8.2 %). Additionally, a fluorescence quenching assay was used to demonstrate that diclofenac predominantly localizes in the external region of the lipid bilayer of SUVs, likely interacting with the polar head groups of the phospholipids. The formulation was purified by evaporation at room temperature for 72h to eliminate the ethanol. Diafiltration methods were tested, but a high diclofenac content was found in the diafiltered portion, losing part of the drug load from the liposomes. The anti-inflammatory efficacy was examined at non cytotoxic concentrations after cell inflammation induction with LPS y qPCR, showing a 70% reduction in the levels of TNF-α and CXCL1, however no reduction was found in IL6 or IL8.
