Hydrophilic gel containing coenzyme Q 10 -loaded liposomes: Preparation, characterization and stress stability tests

Abstract

The aim of this study was to develop a semisolid formulation containing liposomes loaded with coenzyme Q10 (Q10). Q10-loaded liposome dispersion prepared from non-hydrogenated lecithin and characterized for particle size, polydispersity index (PDI), pH value and Q10-content was incorporated into carbomer gel, and a liposome gel was obtained. Liposome gel and liposome-free gel were analyzed for flow properties by continuous rheology measurements, pH values and Q10-content, 48 h after preparation and after a temperature stress test (1 cycle: 24 h at 4 o C, 24 h at 20±2 o C and 24 h at 40 o C), in order to predict their long-term stability. Liposomes were identified in liposome dispersion and liposome gel by freeze fracture electron microscopy (FFEM), while their particle size, PDI and zeta potential were determined by photon correlation spectroscopy (PCS). Q10-loaded liposomes were of small particle size (125 nm), homogeneous (PDI=0.2) and negatively charged, and their incorporation into the gel did not significantly change (p&0.05) their particle size and PDI. FFEM confirmed liposomes presence in the liposome gel. Liposome and liposome-free gel revealed non-Newtonian, shear-thinning plastic flow behavior. The temperature stress test revealed that temperature changes did not significantly influence (p&0.05) the pH value, while they significantly decreased (p&0.05) Q10-content in gels. Q10 was significantly more stable (p&0.05) in liposome gel than in liposome-free gel. Rheological parameters of liposome-free gel significantly changed, in contrast to the liposome gel. In conclusion, Q10-loaded liposome gel suitable for dermal use was developed, exhibiting high stability even after subjecting to the temperature stress test.