title: Formulation and stabilization of norfloxacin in liposomal preparations.
abstract: A number of liposomal preparations of norfloxacin (NF) containing variable concentrations of phosphatidylcholine (PC) (10.8-16.2mM) have been formulated and an entrapment of NF to the extent of 41.7-56.2% was achieved. The values of apparent first-order rate constants (kobs) for the photodegradation of NF in liposomes (pH7.4) lie in the range of 1.05-2.40×10(-3)min(-1) compared to a value of 8.13×10(-3)min(-1) for the photodegradation of NF in aqueous solution (pH7.4). The values of kobs are a linear function of PC concentration indicating an interaction of PC and NF during the reaction. The second-order rate constant for the photochemical interaction of PC and NF has been determined as 8.92×10(-2)M(-1)min(-1). Fluorescence measurements on NF in liposomes indicate a decrease in fluorescence with an increase in PC concentration as a result of formation of NF(-) species which exhibits poor fluorescence. Dynamic light scattering has shown an increase in the size of NF encapsulated liposomes with an increase in PC concentration. The stabilization of NF in liposomes is achieved by the formation of a charge-transfer complex between NF and PC.
authors.affiliation: Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Toll Plaza, Super Highway, Gadap Road, Karachi 74600, Pakistan.
authors.forename: Iqbal
authors.initials: I
authors.lastname: Ahmad
authors.affiliation: Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Toll Plaza, Super Highway, Gadap Road, Karachi 74600, Pakistan; HEJ Research Institute of Chemistry, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi 75270, Pakistan. Electronic address: adeelarsalan@hotmail.com.
authors.forename: Adeel
authors.initials: A
authors.lastname: Arsalan
authors.affiliation: HEJ Research Institute of Chemistry, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi 75270, Pakistan.
authors.forename: Syed Abid
authors.initials: SA
authors.lastname: Ali
authors.affiliation: Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Toll Plaza, Super Highway, Gadap Road, Karachi 74600, Pakistan.
authors.forename: Raheela
authors.initials: R
authors.lastname: Bano
authors.affiliation: HEJ Research Institute of Chemistry, International Center for Chemical and Biological Sciences (ICCBS), University of Karachi, Karachi 75270, Pakistan.
authors.forename: Iqra
authors.initials: I
authors.lastname: Munir
authors.affiliation: Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, Toll Plaza, Super Highway, Gadap Road, Karachi 74600, Pakistan.
authors.forename: Arif
authors.initials: A
authors.lastname: Sabah
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000528:radiation effects; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D006863:Hydrogen-Ion Concentration; D008027:Light; D008081:Liposomes; D009643:Norfloxacin / Q000737:chemistry* / Q000528:radiation effects; D010713:Phosphatidylcholines / Q000737:chemistry; D010782:Photolysis; D013050:Spectrometry, Fluorescence
chemical_list: D000900:Anti-Bacterial Agents; D008081:Liposomes; D010713:Phosphatidylcholines; D009643:Norfloxacin
keywords: Charge-transfer complex; Kinetics; Liposomal preparation; Norfloxacin; Photodegradation; Stabilization