Evaluation of the physicochemical stability and skin permeation of glucosamine sulfate

Glucosamine sulfate (GS) is known to stop the degenerative process of osteoarthritis. Because most of the GS formulation on the market is in the oral form, an alternative formulation such as a transdermal delivery system (TDS) is necessary in order to increase patient compliance. As the initial step to develop a TDS of GS, the physicochemical stability and permeation study in rat skin were examined. Evaluation of the stability of GS at different pHs showed the compound to be most stable at pH 5.0. The degradation rate constant at 25°C was estimated to be 5.93 ×10^- 6 hr^- 1 (t₉₀~ 2.03 years) in a pH 5 buffer solution. Due to its hydrophilic characteristic, low skin permeability was expected of GS. However, the skin permeation rate was determined to be 13.27 µg/cm²/hr at 5% concentration. Results of this study suggest the possibility of developing GS into a transdermal delivery system.