Span-60 based organogels as probable matrices for transdermal/topical delivery systems

The current study describes the development of span-60 based organogels using sunflower oil (SO) as the apolar solvent. The organogels were analyzed for their stability. Subsequently, the stable organogels were characterized by gel-sol transition studies, microscopic analysis, opacity measurement, FTIR spectroscopy, XRD analysis, thermal analysis (using simultaneous TGA-DTA and DSC) and pH measurement. Salicylic acid (SA), model drug, was incorporated within gels and their in vitro release behavior and antimicrobial efficiency against E. coli and B. subtilis were studied. To ascertain the biocompatibility of the gels, hemocompatibility tests were conducted. The stability tests indicated that the gels were inherently stable when stored below 25°C. The gel-sol transition study indicated that as the concentration of the gelator was increased, there was a subsequent increase in the transition temperature. This was also confirmed by the instrumental thermal analysis studied. Microscopic analysis indicated that the solid fibers, formed by the clusters of needle-shaped gelator particles, form the backbone of the organogels structure. Opacity measurements suggested that the rate of gelation of the organogels is higher in organogels with higher gelator concentration. FTIR spectroscopy indicated the presence of hydrogen bonding in both blank and SA-loaded organogels. XRD studies showed that there was a change in the crystallinity of the samples and the change was dependent on the composition of the organogels. The pH of the organogels was found to be within the normal human skin pH range. The release studies indicated that the release of SA from the organogels occurred by Higuchian kinetics and were able to restrict the growth of E. coli and B. subtilis efficiently. The organogels were found to be hemocompatible in nature. Based on the results, the developed organogels may be tried as a drug carrier for transdermal and/or topical formulations