SLN enriched hydrogels for dermal application: Full factorial design study to estimate the relationship between...

When considering dermal administration of cosmeceuticals and/or drugs, the stratum corneum layer of the skin, has a barrier function that limits the penetration of active substances to the targeted skin tissues. Solid lipid nanoparticles/SLNs are colloidal carrier systems, which show superiority in dermal administration of cosmeceuticals/drugs. This superiority results from the ability of the SLNs to penetrate the skin layers easily. However, the main problem in dermal administration of colloidal drug systems is the need for a suitable semisolid vehicle for application as well as patient compliance. The main purpose of this study is to investigate the relationship between hydrogels and SLNs by using 3² full factorial design which simplifies the process by establishing the relationship between variables. Two different types of gel forming agent, hydroxypropyl methylcellulose or Carbopol 934 P, in three different polymer concentration used for preparation of SLN-enriched hydrogels. Formulations evaluated for their hardness and cohesiveness by using 3² full factorial design and the optimum formulations obtained for both gelling agents. As a result, mechanical properties of hydrogels consisting either hydroxypropyl methylcellulose or Carbopol 934 P revealed promotive results for dermal application of SLNs. The type and concentration of the gel-forming agent which is selected as a semisolid carrier for lipid nanoparticles are basic parameters affecting the dermal behavior of the system.