Solid lipid nanoparticles for topical administration of Kaempferia parviflora extracts

Extracts of Kaempferia parviflora (KP) were formulated in solid lipid nanoparticles (SLNs) in order to enhance their transdermal permeability. The KP extracts were entrapped within SLNs by adding them to a melted mixture of oils, surfactants and PEGylating agents and subsequently forming an oil-in-water microemulsion at an elevated temperature. Cooling of this microemulsion resulted in the formation of SLNs. The formulation with the optimum properties was composed of stearyl alcohol as the nanoparticle matrix and Tocopheryl Polyethylene Glycol Succinate (TPGS) as the surfactant. Particle sizes of 82-108 nm were obtained with entrapment efficiencies as high as 87%. The release of the flavonoids from the SLN matrix was measured after suspending them in a Phosphate Buffered Saline (PBS)/Tween 80 solution and demonstrated biphasic patterns. Permeability studies using a skin model composed of human-derived epidermal keratinocytes were conducted in which a topically applied KP extract-loaded SLN was compared to a KP-hydroxypropyl methylcellulose/Tween 80 gel formulation containing KP extract. The amount of total KP flavonoids in the SLNs and gel that had permeated through the skin after 25 hours (95.57 +/- 9.08 and 81.04 +/- 5.82 g, respectively) were found to be significantly different (P < 0.05). In addition, the flux values of three of the flavonoids were greater when incorporated in SLNs.