Study of liposomal drug delivery systems 3. Dynamic in-vitro release of steroids from multilamellar liposomes
| Autor: | E.I. Vargha-Butler, D.E.Lopes de Menezes |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Drug
Liposome Chromatography Cholesterol media_common.quotation_subject Vesicle Phospholipid Surfaces and Interfaces General Medicine chemistry.chemical_compound Colloid and Surface Chemistry chemistry Drug delivery Dissolution testing Physical and Theoretical Chemistry Lipid bilayer Biotechnology media_common |
| Zdroj: | Colloids and Surfaces B: Biointerfaces. 6:269-277 |
| ISSN: | 0927-7765 |
| DOI: | 10.1016/0927-7765(96)01259-3 |
| Popis: | The effects of (a) drug input concentration, (b) liposome composition and (c) hydrophobicity of the encapsulated drug on dynamic in-vitro drug release were studied. Two corticosteroids with different hydrophobicities, triamcinolone (TRM) and hydrocortisone (HC), were encapsulated into multilamellar liposomes (MLVs) by a modified hydration method. Both the input drug concentration and the liposomal composition (i.e. phospholipid (PL) and cholesterol (Chol) molar ratios) were varied independently. The liposomes were prepared with, and the dynamic in-vitro release studies conducted in, distilled water (without any additives), using a USP dissolution apparatus under simulated, finite sink conditions at 37°C. The concentration of the drug released (in aliquot samples taken for 24 h) was determined by UV-spectrophotometry. The in-vitro release of steroids from MLVs indicated a biphasic, apparent first-order release which, in the initial phase, seemed to be diffusion-controlled. The release of drug was dependent upon the drug input concentration and the liposomal composition (i.e. cholesterol content), and was influenced by the hydrophobicity of the encapsulated drug. The results showed that a faster drug release was observed for the less hydrophobic HC-containing preparations than for the hydrophobic TRM-loaded vesicles. It was, however, noted that a higher percentage of HC than TRM remained within the liposomes in all preparations after 24 h. The increasing cholesterol content in liposomes at constant drug input provided a minimum release rate for preparations with a PL/Chol = 1 0.5 (M) ratio. However, a further increase of the cholesterol content promoted the release of hydrophobic steroids from the liposome membrane, indicating a displacement of the steroids by cholesterol within the bilayers of the lipid membrane. |
| Databáze: | OpenAIRE |
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