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KMID : 0370019930070000067
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Chung-Ang Journal of Pharmacal Sciences
1993 Volume.7 No. 0 p.67 ~ p.75
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Physical property of pullulan-coated liposomes and stability against bile salts
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Abstract
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Liposomes have been used as drug carriers for the delivery of peptide, anticancer agent, hormones, and etc. Another possibiltity of liposome as an effective carrier for the oral administration of drugs which are unstable in gastrointestinal tract has been extensively studied in recent years, in the viewpoint of protection of liposome against pH, bile salts and pancreatic lipase in physiological circumstances. Pullulan, a hydrophilic polysaccharide and a coating agent for foods and drugs, was employed in this experiment to coat the DMPC liposomes (MLVs) by adsorption technique. Physical properties of pullulan-coated liposomes were investigated with TEM and particle size analyzer. Turbidity changes were measured and expressed as a relative turbidity (A_t/A_0), in order to compare the stability of uncoated or pullulan-coated liposomes against both pH shock and bile salts attack. The stability of liposomes was independent of pH, since turbidities of liposomes were unchanged for 8 hours in various pH buffer solutions from pH 1.2 to 7.4. On the other hand, from the observations in pH 5.6 or 6.8 buffer solution, pullulan-coated liposomes showed comparative stability against sodium choleate upto 0.15% concentration, although neither uncoated nor pullulan-coated liposomes revealed enough stability against the bile salt at 0.15% or higher concentration. Therefore, it is possible to conclude that pullulan-coated liposmes might be useful as a drug carrier for oral delivery, because of the enhanced stability in gastrointestinal environment. It is still necessary, however, to find out better selections for polymers and coating methods for the purpose of further stabilization of liposomes.
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