Smart polymers are those which exhibit change depending upon the change in environmental conditions. Alteration in polymer properties can be used to: Stimuli responsive polymers can be broadly categorized into micelles, polyplexes and polymer drug conjugates. In this review, we discuss various mechanisms by which polymer systems are assembled in situ to form implanted devices for sustained release of therapeutic macromolecules, and we highlight various applications in the field of advanced drug delivery. Through this paper we emphasize on the role of polymers in existing and novel drug delivery systems both as formulations and in devices, their advantages and limitations. Biocompatible polymers offer a safe passage for drug delivery due to their well engineered molecular architecture according to the transitions in the underlying mechanisms of the biological process. An Academic Publisher, Received 7 November 2015; accepted 11 January 2016; published 14 January 2016. Biodegradable systems can be made either by natural polymers (e.g. The degradable polymers are ruptured into biologically suitable molecules that are assimilated and discarded from the body through normal route. Hydrogels can be made both from natural and synthetic polymers. STRUCTURE: Dextran is can be defined by Leuconostoc mesenteroides (lactic-acid bacteria with the help of which dextran is synthesized using sucrose) which contains a glucan which is (16)-linked and has side chains that are attached to the backbone of 3-positions of glucose units. Surface coating with hydrophilic polymers like Polyethylene glycol (PEG) minimizes their uptake by liver and enhances bioavailability. Gamma PGA has a wide number of potential uses ranging from food and medicine to water treatment. Novel drug delivery systems include micelles, dendrimers, liposomes, polymeric nanoparticles, cell ghosts, microcapsules and lipoproteins. The formulation is simple, which is totally free of organic solvent. Advantages of CRDDS • Controlled delivery of active agent at predetermined rate • Maintenance of optimal and effective drug level for prolonged periods • Reduction of untoward effects like git irritation • Increased patient compliance 7. A number of polymers have been studied systematically from this point of view and there is every indication that the systems described have the potential to become clinically valuable and therefore marketable drug delivery systems. Nanoparticle drug delivery systems are engineered technologies that use nanoparticles for the targeted delivery and controlled release of therapeutic agents. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. Smart polymers for the controlled delivery of drugs – a concise overview. Drugs are bound with magnetic nanoparticles e.g. Particle shape and size depend on variable parameters; among them, polymer type and concentration, stirring speed, pH and type of solvent. Polyglutamic acid (PGA) is a polymer of the amino acid glutamic acid (GA). Topical polymers are mostly prepared by organic polymers such as carbomers  . Implants approved by the FDA for eye: Retisert, Vitrasert, and Ozurdex  . Diffusion based drug delivery systems (as shown in Figure 1) and solvent activated drug delivery systems are the other areas being explored for utilizing the polymers  . The pharmaceutical applications of polymers range from their use as binders in tablets to viscosity and flow controlling agents in liquids, suspensions and emulsions. ・ Polyaprolctone: PCL have been taken into consideration to be used as implantable biomaterial because it has ester linkage that can be hydrolysed in physiological conditions. With the presence of organic solvents and aqueous-organic interfaces on drugs that are encapsulated leads to adverse effects like eliminating the bioactivity of microspheres. Role of polymers in drug delivery will grow steeply in future to handle various unsolved issues. Biodegradable and bio-reducible polymers make the magic possible choice for lot of new drug delivery systems. A polymer (natural or synthetic) is aggregated with a drug in controlled drug delivery and hence it gives a effective and controlled dose of dug avoiding overdose  . es may be in the form of implants for controlled drug delivery. The permeability or the impermeability of the silicone material is decided by the thickness and the grade used. Biodegradable materials are used in medicine and other areas. The polymers mostly used in the non-biodegradable implants include polyvinyl alcohol (PVA), silicone and ethylene vinyl acetate (EVA). A crucial limitation in the development of biodegradable polymer microspheres for controlled-release drug delivery applications is the difficulty of specifically designing systems that exhibit precisely controlled release rates. Retisert, is an intraocular implant for the treatment of noninfectious uveitis that contains fluocinolone acetonide (FA). The implants can be modified into different shapes, such as films, pellets, plugs, rods and discs  . 1. Its hydrophilic nature provides the protection to protein from any immune response. PGA has been known since 1954 as a tough fiber-forming polymer. 2. In most of the implants (a drug delivery system), a permeable polymeric membrane surrounds the core of solid drugs. Studies need to be performed in the areas of surface and bulk properties of polymers as these properties govern their utilization various applications. Due to non biodegradable polymers, there is no initial burst release in diffusion-controlled systems. application examples show the advantages of the array of hundreds of uniform anchored vesicles. ・ Polyethylene glycol: Polyethylene glycol is a hydrophilic polymer. The modification of surface by attaching dextran or PEG to the phospholipid bilayer increases their circulation time in blood. They are stable colloidal system with solid hydrophobic core. Chitosan is a polysaccharide polymer. Its biodegradable, low toxic and biocompatible properties make it suitable for use in drug formulations  . 1. 10. They solubilize by accommodating both hydrophobic and hydrophilic drugs. In these systems, a drug core is surrounded by a polymer film, and the drug release rate is controlled by the properties of the polymer (e.g., polymer composition and molecular weight), the thickness of the coating, and the physicochemical properties of the enclosed drug, such as solubility, drug … 3. It is possible to reproduce the distribution of size of the microsphere particles but the result is not uniform generally and the standard deviation that we get is equal to half of the average size. If the polymer is non- degradable it should be ensured that it is not accumulated within the body and if it is degradable the broken components should be such that they lie below renal threshold level, non toxic and should not produce any immune response  . The amino groups at the dendrimer end react with phosphate groups of nucleic acids and form transfection complexes. Dendrimers are hyperbranched, monodisperse (uniform size particles in a dispersed phase), 3-D molecules of size 1 - 100 nm macromolecules. 2. In diffusion based drug delivery systems drug is dissolved in a non-swell able system or a fully swollen matrix which do not decompose during their activation time. Synthetic biodegradable polymers are also present that include PLA, PLGA, PGA, poly(phosphazenes), poly(caprolactone), poly(anhydride), poly(phosphoesters), poly(cyanoacry- lates), poly(acrylic acid), poly(amides), poly(ortho esters), polyethylene glycol, and polyvinyl alcohol and poly (isobutylcynoacrylate), poly(ethylene oxide), and poly(paradioxane). Contents of the powerpoint on Polymers – Controlled Drug Delivery Systems include: Describe diffusion controlled devices, using polymers Explain the chemically controlled devices and bioerodible polymer Describe the release mechanisms in terms of hydrophilic and hydrophobic polymer. , dendrimers, liposomes, polymeric nanoparticles, cell ghosts, microcapsules and lipoproteins was assumed have! ) [ 19 ] advantages of polymers in controlled drug delivery system pellets behaviour [ 19 ] nontoxic and non-immunogenic time- and distribution-controlled drug delivery through is! 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