Lauroyl/palmitoyl glycol chitosan gels enhance skin delivery of magnesium ascorbyl phosphate.

Palmitoyl glycol chitosan (GCP) hydrogel has been reported as erodible controlled-release systems for the delivery of both hydrophilic and hydrophobic molecules. In this study we prepared lauroyl/palmitoyl glycol chitosan (GCL/GCP) in gel form and evaluated their application for skin delivery of the hydrophilic compound, magnesium ascorbyl phosphate (MAP), which is widely used in cosmetic formulations. Release of MAP from the polymer gels was significantly decreased with increasing concentration of GCL/GCP in the formulations in comparison with glycol chitosan (GC). In both aqueous and 10% ethanol vehicles, MAP flux was increased 1.58- to 3.96-fold of 1% GC from 1% GCL/GCP. Increase in MAP flux was correlated to the increase in GCL/GCP concentration prepared in 10% ethanol vehicle. GCL/GCP, in either water or 10% ethanol vehicles, increased the skin penetration and skin deposition of MAP in comparison with GC, hydroxypropylmethylcellulose, and carbopol, while sustaining its release from the polymer gels. Both the enhancement in skin penetration/deposition and sustained release of MAP were depended on polymer concentration. Also, with increase in polymer concentration, epidermal to dermal drug deposition ratio tended to increase, which will be beneficial to its activity in the epidermis, such as inhibition of tyrosinase and protection from UV damage. These data suggested both GCL and GCP can be applied as delivery vehicles to improve percutaneous absorption of MAP.