title: Preparation and physicochemical characterization of aqueous dispersions of coenzyme Q10 nanoparticles.
abstract: The present study describes a novel pharmaceutical formulation of coenzyme Q10, viz. submicron-sized dispersions of the substance prepared by emulsification of molten coenzyme Q10 in an aqueous phase. Photon correlation spectroscopy reveals mean diameters of 60 to 300 nm depending on process parameters. Coenzyme Q10 nanoparticles remain stable on storage for more than 30 months. Lipophilic drugs can be incorporated into the nanoparticles demonstrating their potential use as a drug carrier system. Transmission electron micrographs of freeze-fractured replica show spherical particles with an amorphous core. Cryo-electron microscopy reveals the coexistence of small unilamellar vesicles in phospholipid stabilized dispersions. Thermoanalysis and X-ray studies indicate that the dispersed and emulsified coenzyme Q10 does not recrystallize even at 4 degrees C over 30 months. These agree with 1H NMR data which demonstrate that coenzyme Q10 molecules have a high mobility when formulated as nanoparticles and that colloidally dispersed coenzyme Q10 remains in the state of a supercooled melt. Despite the high melting point of the bulk material, coenzyme Q10 dispersions represent no suspensions but O/W emulsions according to the IUPAC definition (1).
authors.affiliation: Institute of Pharmaceutical Technology, Technical University of Braunschweig, Federal Republic of Germany.
authors.forename: B
authors.initials: B
authors.lastname: Siekmann
authors.forename: K
authors.initials: K
authors.lastname: Westesen
mesh_terms: D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D004586:Electrophoresis; D004655:Emulsions; D007202:Indicators and Reagents; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D008854:Microscopy, Electron; D010316:Particle Size; D012542:Scattering, Radiation; D014451:Ubiquinone / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D004655:Emulsions; D007202:Indicators and Reagents; D014451:Ubiquinone; C025204:Ubiquinone Q2