Improvement of ascorbyl palmitate stability in lipid nanoparticle dispersions for dermal use

The aim of this work was to investigate and compare the stability of ascorbyl palmitate (AP) in nanoemulsions (NE), solid lipid nanoparticle (SLN) dispersions and oil-loaded SLN (also described as nanostructured lipid carriers, NLC) dispersions of different compositions and stored under different conditions. The SLN and NLC dispersions investigated showed no greater protection of AP from the aqueous environment than nanoemulsions. AP being significantly more stable in formulations from which oxygen had been removed by degassing with argon after preparation. The stability of AP in NLC is influenced most by the total lipid concentration and the type of phospholipid. Higher lipid concentrations and hydrogenated phospholipid in dispersions offer better protection. After one month there was still 85% of non-degraded AP in formulation which contains hydrogenated phospholipid and 10% of lipid. AP stability therefore depends on appropriate selection of concentration and type of lipid, the selection of non-oxidizable components of the carrier system and appropriate choice of storage conditions.