3MATERIALSANDMETHODS3.1Materials.PDFVIP

SLN and NLC for topical delivery of antifungals 3 MATERIALS AND METHODS 3.1 Materials In the present section a physicochemical description of the materials that have been used will be given. All materials have been used as received and were of reagent grade. 3.1.1 Lipid materials The solid lipids used to prepare SLN and NLC consist of a mixture of several chemical compounds which needs to have a sufficiently high melting point, normally higher than 40ºC. According to the purpose of the present investigation, well tolerated and in vivo biodegradable substances were selected for the preparation of the above mentioned lipid particles. The selected raw materials are of GRAS status and are well accepted for human use. ® 3.1.1.1 Dynasan 116 ® Dynasan bases are market products from Contensio Chemicals GmbH (Witten, Germany). These products consist of lipid materials with a high content of microcrystalline triacylglycerols (approximately 90%) and monocarboxilic acids (approximately 10%). The triacylglycerols are glycerol esters of selected, even-numbered and unbranched fatty acids of natural origin, are free from antioxidants and other stabilizing agents. Dynasan® 116 (triacylglycerol of palmitic acid) was the selected solid lipid for the production of clotrimazole-loaded SLN and NLC formulations. Its melting range is between 62ºC and 64ºC [258]. This lipid is hardly soluble both in n-hexane and ether as well in ethanol, and is practically insoluble in water. If Dynasan® 116 is rapidly cooled from the melt, glassy amorphous masses are initially formed which change on standing into crystalline modifications with volume expansion. The stable β modification has a very sharp melting point and is of