title: Incorporation of vitamin D3-derivatives in liposomes of different lipid types.
abstract: Vitamin D3-derivatives are known to be effective in differentiation and proliferation of epidermal cells. However, under certain circumstances, they also may show a hypercalcamic activity which can be a serious limitation in their use for dermatological application. For keeping small the negative side effects of vitamin D3-derivatives and for increasing the drug concentration in the skin we investigated their incorporation in liposomes to optimize their use for psoriasis treatment. The incorporation of vitamin D3-derivatives in liposomes of different lipid composition was studied by HPLC, DSC and freeze-fracture electron microscopy. Incorporation rates of more than 80% of the offered drug were found with significant variations related to the number of hydroxyl-groups in the A-ring, opened or closed B-ring, and some modifications in the side chain of the steroid-molecules. In general, the incorporation rates in egg-PC liposomes have been of about 3% up to 10% higher than in DMPC liposomes. Results, obtained by DSC and freeze-fracture electron microscopy, show a depression of the phase transition of DMPC bilayers by incorporation of vitamin D3 already at a concentration of 10 mol%. These results support the idea that vitamin D3 and its analoga investigated are incorporated into the lipid bilayer modifying there the lipid-lipid interactions.
authors.affiliation: Institute of Organic and Macromolecular Chemistry, Friedrich-Schiller-University Jena, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Merz
authors.forename: B
authors.initials: B
authors.lastname: Sternberg
mesh_terms: D002152:Calorimetry, Differential Scanning; D002762:Cholecalciferol / Q000008:administration & dosage* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D004134:Dimyristoylphosphatidylcholine; D004337:Drug Carriers; D005614:Freeze Fracturing; D008055:Lipids / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry
chemical_list: D004337:Drug Carriers; D008055:Lipids; D008081:Liposomes; D002762:Cholecalciferol; D010758:Phosphorus; D004134:Dimyristoylphosphatidylcholine