Lanolin-based organogels as a matrix for topical drug delivery

The current study deals with the development of lanolin-based emulsion gels by hot emulsification method. Bright-field, phase contrast, and fluorescent micrographs of the gels have shown the uniform distribution of circular water droplets in the formulations. Coalescence of water droplets was observed in gels containing higher proportion of water. Fourier transform infrared spectrophotometric studies indicated absence of Ln-drug chemical interactions. X-ray diffraction studies suggested an increase in amorphousness of the gels with the incorporation of water into the gel structure. The salicylic acid (SA), model drug, release from the gels was found to follow Higuchi kinetics. KrossmeyerPeppas model fitting indicated non-Fickian release of the drug. As the water content of the gels increased, there was a corresponding increase in the rate of release of the drug. The gels showed non-Newtonian and thixotropic flow behavior. The gel to sol transition and melting temperatures of the gels were identified by differential scanning calorimetric (DSC) thermal analysis and falling ball method. DSC thermograms indicated an increase in thermal stability with the increase of water content in the gels. The gels showed sufficient spreadability and biocompatibility characteristics to be used as topical formulations. SA loaded gels showed good antimicrobial efficacy against Bacillus subtilis, a Gram-positive bacterium. Based on the preliminary studies, the developed gels may be regarded as carriers in topical drug delivery. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013