| Peculiar Mechanism of Solubilization of a Sparingly Water Soluble Drug into Polymeric Micelles. Kinetic and Equilibrium Studies. | |
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MedLine Citation:
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PMID: 22462632 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Complementary kinetic and equilibrium studies on the solubilization process of the water sparingly soluble Tamoxifen (TAM) drug in polymeric aqueous solutions have been performed by using the spectrophotometric method. In particular the amphiphilic copolymers obtained by derivatisation of polymeric chain of poly(N-2-hydroxyethyl)-DL-aspartamide, PHEA, with polyethylene glycols, PEG (2000 or 5000 Da), and/or hexadecylamine chain, C16, namely PHEA-PEG2000-C16, PHEA-PEG5000-C16, PHEA-C16, have been employed. Preliminary to the kinetic and equilibrium data quantitative treatment the molar absorption coefficient of TAM in polymeric micelle aqueous solution has been determined. By these studies the solubization sites of the TAM into the polymeric micelles have been determined and the solubilization mechanism has been elucidated through a non-conventional approach by considering the TAM partitioned between three pseudo-phases, i.e. the aqueous pseudo-phase, the hydrophilic corona and the hydrophobic core. The simultaneous solution of the rate laws associate to each step of the proposed mechanism allowed the calculation of the rate constants associated to the involved processes, the values of which are independent of both the copolymer concentration and nature, with the exception of the rate of the TAM transfer from the corona to the core. This has been attributed to the steric barrier, represented by the corona, which hampers the solubilisation into the core. The binding constant values of the TAM to the hydrophilic corona of the polymeric micelles, calculated through the quantitative analysis of the equilibrium data, depend on the thickness of the hydrophilic head group, while those of the hydrophobic core are almost independent on the copolymer type. Further confirmation to the proposed solubilization mechanism has been provided by performing the kinetic and equilibrium measurements in the presence of PHEA-PEG2000 and PHEA-PEG5000 copolymers. Keywords Dissolution kinetic, equilibrium, drug polymeric micelle, binding constant. |
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Authors:
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Maria Liria Turco Liveri; Mariano Licciardi; Luciana Sciascia; Gaetano Giammona; Gennara Cavallaro |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2012-3-30 |
Journal Detail:
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Title: The journal of physical chemistry. B Volume: - ISSN: 1520-5207 ISO Abbreviation: - Publication Date: 2012 Mar |
Date Detail:
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Created Date: 2012-4-2 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 101157530 Medline TA: J Phys Chem B Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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