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  • cationic lipids  (1)
  • lipophilic drug  (1)
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  • 1
    ISSN: 1573-904X
    Keywords: lipoplexes ; cationic lipids ; differentiated Caco-2 cells ; transfection enhancers ; gene delivery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The use of rapidly dividing in vitro cell culture systems to assess the efficiency of gene delivery is now recognised as a poor indicator of in vivo success. We investigated whether differentiated Caco-2 cell filter-cultures would make a more suitable model for studying gene transfer to an epithelium. Methods. Caco-2 cells were cultured on semi-permeable membrane filters into differentiated polarised monolayers. Monolayer differentiation was assessed by monitoring the transport of taurocholic acid. Cells at different stages of differentiation were transfected with DNA/DOTAP lipoplexes and later analysed for reporter gene activity. The uptake of radiolabled DNA was also evaluated at various stages of differentiation. Results. Caco-2 cultures developed a resistance to lipoplex-mediated transfection as early as three days, when some cells were still dividing and undifferentiated. As cultures matured, expression of reporter gene progressively decreased partly due to reduced internalisation of DNA. The resistance to transfection could be overcome in part by pre-treatment of monolayers with calcium chelating agents or surfactants. However, transgene expression in treated monolayers was still significantly lower than that in dividing cultures. Conclusions. Differentiated Caco-2 cells are a more appropriate model for gene-transfer studies to the intestinal epithelium because they demonstrate a resistance to transfection similar to that observed in vivo.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-904X
    Keywords: self-emulsification ; oral delivery system ; formulation ; soft gelatin capsule ; lipophilic drug
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Self-emulsifying drug delivery systems (SEDDSs) represent a possible alternative to traditional oral formulations of lipophilic compounds. In the present study, a lipophilic compound, WIN 54954, was formulated in a medium chain triglyceride oil/nonionic surfactant mixture which exhibited self-emulsification under conditions of gentle agitation in an aqueous medium. The efficiency of emulsifi-cation was studied using a laser diffraction sizer to determine particle size distributions of the resultant emulsions. An optimized formulation which consisted of 25% (w/w) surfactant, 40% (w/w) oil, and 35% (w/w) WIN 54954 emulsified rapidly with gentle agitation in 0.1 N HCl (37°C), producing dispersions with mean droplet diameters of less than 3 µm. The self-emulsifying preparation was compared to a polyethylene glycol 600 (PEG 600) solution formulation by administering each as prefilled soft gelatin capsules to fasted beagle dogs in a parallel crossover study. Pharmacokinetic parameters were determined and the absolute bioavailability of the drug was calculated by comparison to an i.v. injection. The SEDDS improved the reproducibility of the plasma profile in terms of the maximum plasma concentration (C max) and the time to reach the maximum concentration (t max). There was no significant difference in the absolute bioavailability of WIN 54954 from either the SEDDS or the PEG formulations.
    Type of Medium: Electronic Resource
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