DRUG TARGETING

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DRUG TARGETING Seminar by: Ms. Komal R. Nikam II sem.,(Pharmaceutics) AVCOP, Sangamner . 1

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Contents 2

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Introduction 3

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To obtain a desired therapeutic response , the correct amount of drug should be transported and delivered to the site of action with subsequent control of drug input rate. To avoid distribution of drug to other tissues which seems to be unnecessary, wasteful and a potential cause of toxicity. WHY TO TARGET A DRUG? 4

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HISTORY: Paul Ehrlich who proposed drug delivery to as ‘magic bullet’ . Bangham - phospholipid hexagonal liquid crystals. Gregoriadis described drug targeting using novel drug delivery systems as ‘old drug in new clothes’. The Concept of Targeting 5

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Specific features of targeting: Controlled rate Mode of drug delivery to pharmacological receptor specific binding with target cells Protection of the drug from route to the site of action. Higher drug concentration at the site of action and resultant lower concentration at non-target tissue where toxicity might crop-up. The restricted distribution of the parent drug to the non-target site with maximize the benefits of targeted drug delivery. 6

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Entities essential for successful transportation of the loaded drug. Drug vectors which transport and retain drug in route , which elute or deliver it within target. Carriers characteristics can be inherent or acquired (through structural modification) Carriers 7

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An ideal drug carrier should have the following features : 8

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Based on the nature of their origin carriers are categorized as: 9

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Carrier Systems Used for Targeted Drug Delivery 10

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Examples of some drug carrier systems 16

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1.LIPOSOMES : They are spherical vesicles with a phospholipid bilayer. Liposomes helps to improve : Therapeutic index Rapid metabolism Unfavorable pharmacokinetics. Low solubility. Lack of stability. Irritation. 17

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2.Niosomes : Non ionic surfactant vesicles. Enhance the penetration of drug. Used for: Targeting of bioactive agents. Delivery of peptides Transdermal delivery of drug 19

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3.Micelle : Micelle is an aggregate of amphipathic molecules in water, with the nonpolar portions in the interior and the polar portions at the exterior surface, exposed to water. Hydrophobic drugs can be encapsulated into inner core. 20

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4.Polymeric Nanoparticles : Consider as potential carrier due to their applications in drug targeting to particular organs/tissues. Used as carriers of DNA in gene therapy. Ability to deliver proteins, peptides and genes through a oral route of administration . 21

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5.Resealed erythrocytes : Extensively studied for their potential carrier capabilities for the delivery of drugs and drug-loaded microspheres. Used as circulating carriers to a drug for a prolonged period of time in circulation or in target-specific organs, including the liver, spleen, and lymph nodes. 23

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Nanocarrier based targeted drugs in market: 24

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Levels of Drug Targeting 25

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ACTIVE TARGETING First order targeting ( organ compartmentalization) Second order targeting ( cellular targeting) Third order targeting ( intracellular targeting ) 35

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Ligand mediated active targeting could be achieved using specific uptake mechanisms such as : Receptor dependent uptake of LDL Synthetic lipid microemulsions LDL particles coated with the apoprotein 40

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Targeting Ligands 1.Physical Targeting : The selective drug delivery programmed and monitored at the external level with the help of physical means is referred to as physical targeting. 2.Dual Targeting : This classical approach of drug targeting employs carrier molecules, which have their own intrinsic antiviral effect thus synergies the antiviral effect of the loaded active drug. 41

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3.Double Targeting : Drug targeting may be combined with another methodology , other than passive and active targeting for drug delivery systems. 4.Combination Targeting : For the site specific delivery of proteins and peptides.These targeting systems are equipped with carriers, polymers and homing devices of molecular specificity that could provide a direct approach to target site. 42

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Approaches used in Combination Targeting: 43

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Problems associated with targeted delivery systems : These include : Rapid clearance of targeted systems specially antibody targeted carriers. Immune reactions against intravenous administered carrier systems. Target tissue heterogeneity. Problems of insufficient localization of targeted systems into tumour cells. Diffusion and redistribution of released drug leading to nonspecific accumulation 44

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Conclusion & Prospect 45

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As this approach provides drug at right site in the body, at the right time, at the right concentration so there is no chance of side effect & no barrier at target site during clearance process. Utilizing all this, most of formulation are in market and many more in clinical trials. In future this approach help in treatment of life threatening diseases like cancer and severe infectious diseases. 46

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References 47

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References 1.Khar R. k., Diwan Manish, ‘Targeted Delivery of Drugs’, In: Jain N.K.,editor , ‘Advances in Controlled & Novel Drug Delivery’, first edition 2001,CBS publishers & Distributors, New Delhi, pg.no . 452-464. 2.Vyas S.P., Khar R.K., ‘Targeted and Controlled Drug Delivery: Novel Carrier System’, first edition 2004, CBS Publishers & Distributors, New Delhi, pg.no.487-511. 3. Karanth H., Murthy Rayasa S.R., ‘Nanotechnology in Brain Targeting’, International journal of Pharmaceutical sciences and Nanotechnology’, Volume 1, Issue 1, April-June 2008, pg. no. 9-24. 4.Hillery A., Lloyd A.,Drug delivery and targeting’for pharmacist and pharmaceutical scientist, First Indian reprint 2010,CRC Press,New York, pg.no.117-143. 48

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THANK YOU!!! 49

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Question??? 50