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- Kronberg, B, et al.
(author)
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Preparation and evaluation of sterically stabilized liposomes: colloidal stability, serum stability, macrophage uptake and toxicology
- 1990
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In: Journal of Pharmaceutical Sciences. - 0022-3549 .- 1520-6017. ; 79, s. 667-671
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Journal article (peer-reviewed)abstract
- Sterically stabilized liposomes were produced by incorporating a nonionic surfactant, polysorbate 80 (Tween 80), into the lipid bilayer. The sterically stabilized liposomes exhibited a superior entrapment stability compared with surfactant-free liposomes (i.e., liposomes prepared with lipids and cholesterol). The sterically stabilized liposomes were stable at high calcium ion concentrations, and liposome-entrapped carboxyflourescein was retained within the stabilized liposomes in the presence of serum for at least 5 h. The macrophage uptake of the sterically stabilized liposomes was comparable to that of liposomes containing lipids and cholesterol. The sterically stabilized liposomes were non-toxic, in concentrations up to 3.0 mM, to macrophages. These results indicate that polysorbate 80 can be used to produce stable liposomes without changing the uniqe macrophage distribution of this drug delivery system.
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- Carlfors, J, et al.
(author)
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Lidocaine in microemulsion - A dermal delivery system
- 1991
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In: Journal of Dispersion Science and Technology. - 0193-2691 .- 1532-2351. ; 12, s. 467-482
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Journal article (peer-reviewed)abstract
- In order to obtain a microemulsion that is stable at skin tempeature, the regions of existance of microemulsions of water and isoproptyl myristate were studied as a function of hydrophilelipophile balance (HLB) of nonionic surfactant mixtures. The microemulsion dissolves large amount of the local anaesthetic lidocaine. The amount of dissolved lidocaine in the microemulsion was proportional to the isopropyl myristate content and limited to its solubility in this solvent. The addition of lidocaine lowered the phase inversion temperature (PIT) of the system and increased the temperature range for microemulsion stability. The structure of the microemulsion, as investigated by proton Fourier transform pulsed-gradient spin-echo NMR spectroscopy, was found to be bicontinous. The physico-chemical properties of the microemulsion as well as the low toxicity of its components result in formulation intendend for topical administation.
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