Gastro Retentive Drug Delivery System

Gastro Retentive Drug Delivery System

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  Gastro-retentive drug delivery system CSJMUNIVERSITY KANPUR University Institute of Pharmacy PRESENTED BY Manish Kumar M.Pharm 1st Year Specialization Pharmaceutics
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  CONTENTS  Introduction  Needfor GRDDS  Advantages and Limitations  Ideal Characteristics for GRDDS  Types andApproaches of GRDDS  Marketed Products of GRDDS  Conclusion  References
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  INTRODUCTION  Gastro retentivedrug delivery is an approach to prolong gastric residence time.  Thereby targeting site-specific drug release in the upper gastrointestinal tract (GIT) for local or systemic effects  Gastro-retentive delivery is one of the site specific delivery of the drugs at stomach.  It is obtained by retaining dosage form into stomach and drug is being released at sustained manner to specific site either in stomach or intestine.
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  o Improve thebioavailability of drugs. o To overcome physiological adversities o These are the drug delivery systems which possess the ability of retaining the drug in the GIT particularly in the stomach for prolonged period of time. o Degraded without causing any gastric disturbances.
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  NEED FOR GRDDS Conventional oral drug delivery system (DDS) is complicated by limited gastric residence time (GRT).  Rapid GI transit can prevent complete drug release in absorption zone & reduce the efficacy of the administered dose since the majority of drugs are absorbed in stomach or the upper part of small intestine.  To overcome these limitations by various approaches have been proposed to increase gastric residence of drug delivery systems in the upper part of GIT includes gastro retentive drug delivery system (GRDDS).
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  ADVANTAGES  Enhanced bioavailability Sustained drug delivery/reduced frequency of dosing  Targeted therapy for local ailments in the upper GIT  Reduced fluctuations of drug concentration  Improved selectivity in receptor activation  Reduced counter-activity of the body  Extended effective concentration.  Minimized adverse activity at the colon
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  IDEAL CANDIDATES OFDRUG FOR GRDDS  Drugs acting locally in the stomach.  E.g.Antacids and drugs for H. Pylori viz.,Misoprostol.  Drugs that are primarily absorbed in the stomach.  E.g.Amoxicillin  Drugs that is poorly soluble at alkaline pH.  E.g. Furosemide, Diazepam, Verapamil, etc.  Drugs with a narrow absorption window.  E.g. Cyclosporine, , Levodopa, Methotrexate etc.  Drugs which are absorbed rapidly from the GI tract.  E.g. Metronidazole, tetracycline.  Drugs that degrade in the colon.  E.g. Ranitidine, Metformin.  Drugs that disturb normal colonic microbes.  E.g. antibiotics against Helicobacter pylori.
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  TYPES AND APPROACHESOF GRDDS
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  HIGH DENSITY SYSTEM These have high density than that of gastric fluids[1.4g/cc]  Zinc oxide , iron oxide, titanium dioxide barium sulphate are used as a inert heavy core.  Heavy pellets might Remain longer in Stomach
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  Floating Drug DeliverySystems.  FDDS has a bulk density less than gastric fluids and so remain buoyant in the stomach with out affecting the gastric emptying rate for a prolonged period of time.  F= F buoyancy-F gravity={Df-Ds}gv where, F= total vertical force. Df= fluid density Ds=object density V= volume G= acceleration due to gravity.
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  Swelling and expandingsystem  The swelling is usually results from osmotic absorption of water.  The device gradually decreases in volume and rigidity as a result depletion of drug and expanding agent and/or bioerosion of polymer layer, enabling its elimination.
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  RAFT FORMING  Thissystem is used for delivery of antacids and drug delivery for treatment of gastrointestinal infections and disorders.  The mechanism involved in this system includes the formation of a viscous cohesive gel in contact with gastric fluids, forming a continuous layer called raft.
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  Evaluation ◦ A. InVitro Evaluation a. Floating system 1. Buoyancy lag time 2. Floating time 3. Resultant weight B. In Vivo Evaluation 1. Radiology 2. Scintigraphy 3. Gastroscopy 4. Magnetic marker monitoring 5. 13C-octanoic acid breath test.
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  CONCLUSION  Gastro retentivedrug delivery systems has proved to be a novel approach of controlled delivery of drugs that exhibit an absorption window.  All these drug delivery systems have their own advantages and drawbacks.  From this we can concluded that GRDDS can be a better alternative than other oral drug delivery system having a retentive drug delivery system
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  REFERENCES  S. P.Vyas,Roop K. Khar, CONTROLLED DRUG DELIVERY – Concepts & Advances, Vallabh Prakashan, page no. 196-217.  https://www.slideshare.net/UmasankarKrishnamaraju/gastrorentive- drug-delivery-systems  N K Jain. Gastroretentive drug delivery systems Garima Chawla, Piyush Gupta and Aravind K. Bansal editors. Progress in controlled and novel drug delivery systems. New Delhi. ,