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Philos Trans A Math Phys Eng Sci. 2016 Jul 28;374(2072). pii: 20150128. doi: 10.1098/rsta.2015.0128.

Determining drug release rates of hydrophobic compounds from nanocarriers.

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Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA.
Department of Pharmaceutical Technology, Institute of Pharmacy, Friedrich-Schiller-Universität Jena, Jena, Germany.
J. Crayton Pruitt Family Department of Biomedical Engineering and Department of Chemical Engineering, University of Florida, Gainesville, FL 32611, USA.
Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA


Obtaining meaningful drug release profiles for drug formulations is essential prior to in vivo testing and for ensuring consistent quality. The release kinetics of hydrophobic drugs from nanocarriers (NCs) are not well understood because the standard protocols for maintaining sink conditions and sampling are not valid owing to mass transfer and solubility limitations. In this work, a new in vitroassay protocol based on 'lipid sinks' and magnetic separation produces release conditions that mimic the concentrations of lipid membranes and lipoproteins in vivo, facilitates separation, and thus allows determination of intrinsic release rates of drugs from NCs. The assay protocol is validated by (i) determining the magnetic separation efficiency, (ii) demonstrating that sink condition requirements are met, and (iii) accounting for drug by completing a mass balance. NCs of itraconazole and cyclosporine A (CsA) were prepared and the drug release profiles were determined. This release protocol has been used to compare the drug release from a polymer stabilized NC of CsA to a solid drug NP of CsA alone. These data have led to the finding that stabilizing block copolymer layers have a retarding effect on drug release from NCs, reducing the rate of CsA release fourfold compared with the nanoparticle without a polymer coating.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'.


dissolution; drug release; magnetic nanoparticles; nanocarriers; nanoparticles

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