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Unformatted text preview: MSE/BioE 118 Lectures #20-21 Drug Delivery Systems 1. General Controlled drug release 2. Diffusion-Controlled Delivery Systems Membrane-controlled devices 3. Chemically-Controlled Delivery Systems and Devices Biodegradable polymers Mechanisms of chemical degradation Effect of degradation on material properties Mechanisms of absorption and clearance 4. Design Example: Protein delivery from PLGA microspheres 5. Design Example: Drug-eluting Stents 6. Drug Delivery from Liposomes 1. General Controlled drug release Ratner, Biomaterials Science 1. General Controlled drug delivery (Robert Langer, MIT) Why? Site directed delivery of molecule allows for Higher local doses Minimal or little systemic distribution Delivery of challenging molecules (e.g. short half-life) New approaches to untreatable diseases Macromolecules for controlled delivery Antibiotics Steroids Hormones Growth and differentiation factors Gene therapy (oligonucleotides, DNA) Chemotherapy agents Pharmacokinetics & Toxicity Physicochemical Properties of Drug Design of Formation & Delivery Clinical Indications (acute/chronic) Adapted from Cleland and Langer, ACS v.567, 1994 Biological Function Biological activity Drug Stability in vitro / in vivo 1. General Delivery formulation 1. General Classification of controlled release systems Ratner, Biomaterials Science J = D dC m dx J ux in g/cm 2-sec D diffusion coefcient cm 2 /sec C m concentration in membrane g/cm 3 Ficks rst law J = DK C l K partition coefcient l thickness of membrane J = EDK C l E porosity (# pores/area) tortuosity 2. Diffusion-Controlled Delivery Systems2....
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- Fall '11