Skip to main content
UploadLanguage (EN)Support
BusinessMobileSocial MediaMarketingTechnologyArt & PhotosCareerDesignEducationPresentations & Public SpeakingGovernment & NonprofitHealthcareInternetLawLeadership & ManagementAutomotiveEngineeringSoftwareRecruiting & HRRetailSalesServicesScienceSmall Business & EntrepreneurshipFoodEnvironmentEconomy & FinanceData & AnalyticsInvestor RelationsSportsSpiritualNews & PoliticsTravelSelf ImprovementReal EstateEntertainment & HumorHealth & MedicineDevices & HardwareLifestyle
R.A.S. Institute of Pharmacy Mau UP IND, profile picture
Uploaded byR.A.S. Institute of Pharmacy Mau UP IND
PPTX, PDF129 views

B.Pharm POLYMERS UNIT-1,CHAP-2[NDDS].pptx

A polymer is a large molecule (macromolecule) made up of many small repeating units called monomers, which are joined together by covalent bonds. Examples: Natural polymers: Cellulose, Starch, Proteins, DNA Synthetic polymers: Nylon, PVC, Polyethylene

Education◦
Download to read offline
POLYMER S ANUJ KANNAUJIA ASSISTANT PROFESSOR [DEPARTMENT OF PHARMACEUTICS] RAS INSTITUTE OF PHARMACY PIPRIDEEH MAU
 INTRODUCTION:  The term polymer is derived from greek words poly means many and meros means unit or parts.  The POLYMERS word is used as a synonyms for plastic.  A polymer with two different monomers is knowns as copopolymer or homopolymer.  All plastics are polymers,but not all polymers are plastics.  The compounds having high molecular masses and formed by monomers are termed polymers and momomers are connected by co- valent chemical bond. A polymer with two different monomers is knowns as copopolymer or homopolymer.  Structure: Monomer linked → with covalent bonds form → polymer.  CLASSIFICATION A. Based on the source B. Based on the types of polymerization C. Based on the degradability. D. Based on the structure of polymers E. Based on the molecular forces F. Based on the monomers. G. Based on the tacticity H. Based on the nature of polymer-water interaction
A]BASED ON THE SOURCE  Based on the source from which polymers are derived, they are classified into the following three types. 1 Natural polymers:  These polymer occur in nature ,and are also knows as knowns as biopolymers.  Example :Pectin, chitosan, alginate, gelatin, albumin, collagen, natural rubber, cellulose, natural silk, protein, starch, etc. 2] Semi-Synthetic Polymers  These polymers are prepared by chemically modifying the natural polymers, whose physical properties are altered by chemical treatment  Example :Hydrogenated, cellulosic, cellulose nitrate, methyl cellulose, polyethylene, polylactic acid, polypropylene, polyglycolic acid, polyhydroxybutyrate, polyanhydride, polyacrylamide, etc. 3] Synthetic Polymers:  These polymers are synthesised in the laboratory, and are also known as man- made polymers.  Example :Hydroxyl propyl cellulose, methyl cellulose, hydroxyl propyl methyl
B]BASED ON THE TYPES OF POLYMERISATION  Based on the type of polymerisation by which polymers are formed, they are classified into the following two types. 1 Addition polymer:  Same kind of monomers are straight forwardly added.  The monomer molecules bond to each other without loss of any other molcules or atoms.  Formed by the addition of monomer molcules processing double or triple 2] Condensation polymer:  Two different monomer molecules bond to each other with loss of any molecules or atoms(usually water and sometimes ammonia.)  Example polyesters and polyamides(nylon.) bonds. Example n(CH2 =CH2) ethylene -(CH2-CH2)-polyethene.
C. Based on the degradability  Based on the capability to degrade, polymers are classified into the following two types: 1 Non-Biodegradable Polymers:  These polymers do not undergo natural degradation in the body.  Examples - Polyethene Vinyl Acetate (PVA), Polyethene Vinyl Chloride (PVC), Polydimethyl Siloxam (PDS), Polyether Urethane (PEU). Ethyl Cellulose (EC), Cellulose Acetate (CA), 2] Biodegradable Polymers:  These polymers undergo natural degradation in the body.  Example: Polycaprolactone (PCL), Polylactic Acid (PLA), Polyglycolic Acid (PGA), Poly(Lactic-co-Glycolic) Acid (PLGA), etc. are the examples of biodegradable polymers
D. Based on the structure of polymers  Based on the structure, they are classified into the following three types: 1 Linear polymers on structure:  In these polymer,the monomer are linked with one another and make a long straight chain.  These chain donot have any side chain.  Example polythene,PVC,nylon,polyester etc. 2] Branched polymers on structure:  These polymer posses a straight long chain having different side chain.  Example polypropylene,amylopectin,glycogen etc 3] Cross-Linked polymers on structure:  In these polymer,two linear chains are joined to each other through covalent bonds.  These polymer have 3D structure  Example bakelite ,melamine,formaldehyde resins etc.
E. Based on the molecular forces  The mechanical properties of polymers, such as tensile strength, toughness, and elasticity, rely on intermolecular forces, such as Van der Waals forces and hydrogen bonding. Based on these forces, polymers are classified into the following types: 1 Thermoplastic Polymers:  These polymers are one dimensional which have strong intra molecular covalent bond and weak intramolecular Vander Waals bonds.  They can be softened on heating and toughened on cooling at room temperature.  They are either linear or branched chain polymers.  They can be recycled multiple times.  Example Polythene, polystyrene, PVC, etc. use in bottles,drug container,packaging materials etc. 2] Thermosetting Polymers:  These polymers are hard and become infusible on heating &they are not reusable.  They do not soften on heating under pressure and they cannot be remoulded.  They are either very Strong bond (cross-linked or heavily branched molecules).  Example Bakelite, urea, formaldehyde resins, etc. use in electric switch,circuit board,hand resistant handles.
F.Based on the monomers.  Based on the types of momomers ,polymers are classified into the following two types: 1.Homopolymers:  These polymers contain a single type of repeat unit eg Polystyrene. 2.Hetropolymers (Copolymers):  These polymers are made up of two different monomers eg. Butadiene- styrene rubber. 4] Fibres:  These are thread-forming solids having high tensile strength and modulus.  These properties can be allocated to the strong intermolecular forces (such as hydrogen bonding), which lead to close packing of chains and impart crystalline nature.  Fibres are used in textile industries. Polyamides (nylon 6,6), polyesters (terylene), etc. are the examples of fibres. Use in clothes,surgical sutures,ropes.
 Difference between Homopolymer & Copolymer
G.Based on the tacticity:  Arrangement of side groups (substituents) along the polymer chain.Affects polymer properties like strength, melting point, and crystallinity. 1. Atactic – Side groups arranged randomly.Amorphous, soft, less strength 2. Syndiotactic – Side groups alternate sides regularly.Also crystalline, good strength. 3. Isotactic – All side groups on the same side of the chain.Highly crystalline, strong.
H.Based on the Nature of Polymer-Water Interaction  Based on the nature of interaction between polymer and water, polymers are classified into the following three types: 1) Hydrophobic Polymers:  These polymers are water-insoluble due to the presence of non-polar functional groups.  Ethyl cellulose and polydimethyl siloxane are the examples of hydrophobic polymers. 2) Hydrophilic Polymers:  These polymers are water-soluble due to the presence of polar or charged functional groups. HPMC, NaCMC, chitosan, sodium alginate, etc. are the examples of hydrophilic polymers. 3) Hydrogels:  These polymers swell (but do not dissolve) on coming in contact with water.  Polyhydroxy ethyl methyl acrylate, cross-linked Polyvinyl Alcohol (PVA), Polyvinyl Pyrrolidone (PVP), polyacrylamide, and natural
 PROPERTIES  It should be inert and compatible with the environment,  It should be non-toxic  It should be easy to administer,  Its fabrication should be easy and inexpensive & poor tensile strength  It should have a good mechanical strength.  Flexible,tough and posses very good heat resisting property.  Low density  Excellent adhesion quality.
 ADVANTAGE  High resistance to chemical  Localized delivery of drug.  Being lighter  Comparable structural strength with lower weight  It delivers drug at a constant rate of controlled release for a prescribed time period.  The carrier of polymer degrades into non-toxic and absorbable sub-units that get metabolised lately.  They breakdown into biologically acceptable molecules which get metabolised and eliminated from the body via normal metabolic pathways.  DISADVANTAGE  Low mechanical properties.  They cannot tolerate extreme temperature; for example, plastics immediately melt down on coming in contact with heat.  Biodegradable polymers show substantial dose dumping at some points after implantations.
 APPLICATION OF POLYMER IN FORMULATION OF CONTROLLED RELEASE DRUG DELIVERY SYSTEM A] Controlled Release Dosage Forms: 1.Reservoir Systems III . • Examples of polymers which are usually used as polymeric coatings include poly (ethylene vinyl acetate), silicone, ethyl cellulose and various acrylate copolymers. • The drug release from these systems occurs by a number of steps, I. Partitioning of the drug into the polymeric coat. II. The drug then diffuses from the inner to the outer side of the coat/layer due to the difference in concentration gradient and Partitioning into the surrounding biological media 2. Matrix Systems: • In matrix designed drug delivery systems, the drug is homogeneously dispersed, either at the molecular scale or as solid particles, within a polymeric medium. • • Matrix drug delivery devices are composed of drug that is either dissolved or dispersed within a polymeric matrix. • • Diffusion of the drug through the polymeric matrix is the rate-controlling
3.The Ocusert System: • The delivery of therapeutic agents to the eye for the treatment of disorder of the eye (e.g. glaucoma). • One method by which the efficiency of ocular drug delivery may be improved is through the use of polymeric implants that are implanted under the lower cul-de-sac of the eye. 4. Biodegradable Systems: • Biodegradable systems are those in which a therapeutic agent has been incorporated into a matrix that is composed of a biodegradable polymer. • These include poly(lactic acid), poly(glycolic acid) and their copolymers poly(ortho esters) and polyanhydrides 5. Osmotically Controlled Drug Delivery Systems: • In these systems the difference between the osmotic pressure within a formulation and the surrounding biological fluids is used as the driving force for drug release. • The first osmotically controlled drug delivery systems were composed of two primary regions, namely a tablet core (containing the drug and when required an osmotic pressure modifier) and a semi-permeable membrane.
6. pH Responsive Drug Release: • Within the gastrointestinal tract a range of pH values exist, ranging from about one in the stomach to neutrality within the intestine. • Targeting drug release within certain regions of the g.i.t. as a method to enhance drug stability within acidic fluids or to reduce the irritant effects of certain drugs has been used for several decades. • For example, enteric polymers have been used as tablet coatings for this purpose, examples of which include cellulose acetate phthalate and cellulose acetate butyrate. • These polymers are insoluble in low pH environments; however they are soluble in the less acid regions of the gastrointestinal tract 7. Swelling Controlled Release Systems: • In many drug delivery systems, the dimensions of the dosage form will change during the course of drug release due to swelling of the polymer matrix. • Although the mechanism for drug release is diffusion. • Examples of systems that exhibit swelling controlled release are physically and chemically crosslinked gels. • In terms of controlled drug release, chemically Crosslinked hydrogels
(B) Immediate drug release dosage forms 1.Tablets: • Polymers including; polyvinyl pyrrolidone and hydroxypropyl methyl cellulose (HPMC) are found to be a good binder which increases the formation of granules that improves the flow and compaction properties of tablet formulations prior to tableting. 2.Capsules: • Many of the polymeric excipients used to "bulk out" capsules fills are the same as those used in intermediate release tablets. For hard and soft shell, gelatin is most often used. • By recent advances, HPMC has been accepted as alternative material for hard and soft capsules. (C) Modified drug release dosage forms: • To achieve gastro-retention, mucoadhesive and low density polymers have been evaluated their ability to extend gastric residence time by bonding to the mucus lining of the stomach and floating on top of the gastric contents respectively.
(D) Extended release dosage forms: • Extended and sustained release dosage forms prolong the time that, systemic drug levels are within the therapeutic range and thus reduce the number of doses the patient must take to maintain a therapeutic effect there by increasing compliance. • The most commonly used water insoluble polymers for extended release applications are, the ammonium ethacrylate copolymers, cellulose derivatives; ethyl cellulose and cellulose acetate, and polyvinyl derivative; polyvinyl acetate. (E) Gastro retentive dosage forms: • Gastro retentive dosage forms offer an alternative strategy for achieving extended release profile, in which the formulation will remain in the stomach for prolonged periods, releasing the drug insitu, which will then dissolve in the liquid contents and slowly pass into the small intestine.
THANK YOU