FLOATING MICROSPHERES

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FLOATING MICROSPHERES:

FLOATING MICROSPHERES Sravani Boyapati , Department of Pharmaceutical Technology, SVCP, Bhimavaram

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Introduction Advantages Mechanism Polymers Methods of preparation Characterization Conclusion CONTENTS

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These are Gastro Retentive Drug Delivery Dosage Systems (GRDDS) based on Non-Effervescent Approach. Gastro Retentive Floating Microspheres are low density systems that have sufficient buoyancy to float over the gastric contents and remain in stomach for prolonged period and slowly released the drug at desired rate with reduced fluctuations in plasma-drug concentration. These are having size 200µm. 1/16 INTRODUCTION

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Increase Patient Compliance. Bioavailability enhances. Gastro Retention Time is increased. Enhanced absorption of Drugs. Drug release in Controlled manner for prolonged period. Avoid gastric irritation. Better therapeutic effect of short half-life drugs can be achieved. No risk of dumping and released, drug uniformity compared to Single unit Floating drug delivery dosage systems. Site Specific drug delivery to stomach can be achieved. DISADVANTAGES drugs that may irritate the stomach lining or are unstable in its acidic environment should not be formulated in gastroretentive systems. drugs such as isosorbide dinitrate, that are absorbed equally well throughout the GI tract will not benefit from incorporation into a gastric retention system. 2/16 ADVANTAGES

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MECHANISM Liberation of drug due to polymer degradation / erosion. Self diffusion from the pore. Osmotically driven burst mechanism. The drug release and better floating properties depend up on type of polymer, Plasticizer and solvent employed for the preparation. 3/16

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POLYMERS: Eudragit Cellulose acetate Chitosan Carbopol Acrycoat Acrylic resins Methocil Agar Polyacrylates Poly Carbonates PVA PEO CHANNELING AGENTS : HPMC citric acid PVP PEG SOLVENTS: Acetone Dichloromethane Water Acetonitrile Chloroform Ethyl cellulose Ethanol Cyclohexane Isopropanol Ethyl acetate 4/16

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Single Emulsification Solvent Evaporation Technique Double Emulsification Solvent Evaporation Technique Coacervation Phase Separation Technique Spray Drying and Spray Coating Solvent Extraction Emulsion Polymerization Technique Bulk Suspension Other Methods include Pan coating, Fluid Bed Coating, Hot-Melt Microencapsulation 5/16 GENERAL METHOD OF PREPARATION

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O/W (Clonazepam) W/O(Timolol) 6/16 1) SINGLE EMULSIFICATION SOLVENT EVAPORATION TECHNIQUE

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2) DOUBLE EMULSIFICATION METHOD Aqueous solution of polymer + Drug dispersion in oil/organic phase, vigorous homogenization (sonication) Primary emulsion addition of aqueous solution of PVA W/O/W multiple emulsion addition of large aqueous Phase MICROSPHERES in solution Evaporation/ Centrifugation, washing, Drying MICROSPHERES 7/16

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3) COACERVATION PHASE SEPAERATION TECHNIQUE Aq./organic solution of polymer Drug dispersed or dissolved in the polymer solution Phase separation by salt addition, non solvent addition, addition of Incompatible polymer etc Polymer rich globules Hardening Microspheres in aqueous/organic phase separation /drying MICROSPHERES 8/16

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9/16

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4) SPRAY DRYING AND SPRAY COATING: Polymer dissolve in volatile organic solvent (acetone, dichloromethane) Drug dispersed in polymer solution under high speed homogenization Atomized in a stream of hot air Due to solvent evaporation small droplet or fine mist form Leads to formation of Microspheres Microspheres separated from hot air by cyclone separator , Trace of solvent are removed by vacuum drying 10/16

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5) SOLVENT EXTRACTION: Drug is dispersed in organic Polymer in organic solvent ( water miscible organic solvent solvent such as Isopropanol) Organic phase is removed by extraction with water (This process decreasing hardening time for microspheres) Hardened microspheres 11/16

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6.a) EMULSION POLYMERIZATION: Monomer + Aq.Solution of NaOH, Initiator, Surfactant , Stabilizer Dispersion with vigorous stirring Micellar solution of Polymer in aqueous medium Polymerization Microspheres formation Centrifugation, washing, drying MICROSPHERES 6.b) BULK POLYMERIZATION: Monomer + Bioactive material + Initiator Heated to initiate polymerization Initiator accelerate rate of reaction Polymer(Block) Moulded/fragmented MICROSPHERES 12/16

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6.C) SUSPENSION POLYMERIZATION: Monomer + Bioactive material + Initiator Dispersion in water and stabilizer Droplet Vigorous ,Agitation Polymerization by Heat Hardened microspheres Separation and Drying MICROSPHERES 13/16

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Micromeritic Properties: A) Particle size & shape B) True, Tapped densities C) Flow Property determination Surface chemistry by Electron Spectroscopy Entrapment efficiency Release study: Usually carried out in phosphate saline buffer ph 7.4. Two method 1) Rotating paddle dissolution apparatus. 2) Dialysis method 14/16 CHARACTERIZATION

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APPLICATIONS Used as carriers for drugs. Eg: Antifungals, Sulphonamides, Antivirals, Antibiotics. Effective in sparingly soluble and insoluble drugs. Eg: Griseofulvin, P-Nitro aniline Microspheres of NSAIDS reduces gastric irritation. Eg: Aspirin, Ibuprofen, Used to treat gastritis, oesophagitis, stomach and duodenal ulcers. Eg: Terfinadine and Tranilast 15/16

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The Development of Floating microspheres can be advantageous for the administration of some important drugs and significantly improves their therapeutic outcome. Gastroretentivity of a dosage form can be achieved by the development of devices that can float over the gastric fluids. 16/16 CONCLUSION

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Chawla G. Gupta P, Koradia V, Bansal AK. Pharma Tech. 2001: 27 (7): 50-51. Vyas SP. Khar “Targeted and Controlled drug delivery novel carrier systems”, 1 st Edition, 2002. 417-54. www.science direct.com http://www.daviddarling.info/encyclopedia/M/floating microsphere.html REFERENCES

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