Polymers of Controlled Drug Delivery System
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The document discusses the role of polymers in controlled release drug delivery systems, detailing their types, properties, and applications in pharmaceuticals. It highlights the advantages of both synthetic and natural polymers, as well as the importance of smart polymers that respond to environmental stimuli for targeted and sustained drug delivery. Moreover, specific examples of pH-sensitive and temperature-sensitive polymers are provided, illustrating their mechanisms and benefits in enhancing drug stability and patient compliance.
Polymers of Controlled Drug Delivery System
- 1. POLYMERS Introduction Classification Advantages Properties Applications of polymers in formulation of controlled release drug delivery systems
- 2. Definition: Polymers are compounds with high molecular masses formed by monomers. The word poly means ‘many’ and meros means ‘units or parts’ in Greek Because of their unique properties polymers are used in pharmaceuticals The new technology in polymer based drug release system offer possibilities in administration of drugs Pharmaceutically these polymers are used as a binder in tablets, flow controlling agents in liquids, suspensions and emulsions, as film coating agents to mask unpleasant taste of drug, protective and stabilizing agents Polymers for CRDDS The polymers, being an integral part of drug delivery technology, play an important role in terms of giving controlled release to the therapeutic moieties for long periods Introduction to Polymers for CRDDS
- 3. It is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three- dimensional networks Polymerization
- 4. Properties
- 5. Drug release from polymer
- 7. Different types of polymers in Pharmaceutical drug delivery system
- 8. Synthetic Polymers Different types of synthetic polymers are being investigated for their performance in drug delivery. The synthetic polymers provide various advantages like Sustained action of the drug with the steady release drug stability Can be used as sutures, tissue adherent materials, hemostats, and drug delivery carriers The biodegradable polymers provide advantages like targeted drug delivery, controlled release, and stability of drug and stable release with time Localized delivery of drug : The product can be implanted directly at the site where drug action is needed and hence systemic exposure of the drug can be reduced. Especially for toxic drugs which are related to various systemic side effects Sustained delivery of drug : The drug encapsulated is released over extended period and hence eliminates the need for multiple injections. This feature can improve patient compliance especially for drugs for chronic indications, requiring frequent Injection Stabilization of the drug : The polymer can protect the drug from the physiological environment and hence improve its stability in vivo. This feature makes this technology attractive for the delivery of labile drugs like proteins Different types of polymers to CRDDS: Uses and Properties Synthetic polymers
- 9. Synthetic polymers: Types, Examples and Properties
- 10. Natural Polymers • The natural polymers are widely used in drug delivery due to their abundant availability, good compatibility, and important role in deciding release rate of the dosage form • These polymers can be modified chemically to alter the release properties. The various polymers like chitosan, alginate, and hyaluronic acid are commonly used in drug delivery systems Natural Polymers
- 11. Natural polymers: Types, Examples and Properties
- 12. Smart Polymers • Smart polymers are the ones that show a change with the change in environmental factors • The factors can include pH change, temperature, light, and pressure difference • Designing of CRDDS using smart polymers leads to accurate and programmable delivery of a drug. These offer a drug delivery platform that can be utilized to deliver drugs at a controlled rate and in a stable and biologically active form Smart Polymers various stimuli responsible for controlling drug release from smart polymeric drug delivery systems
- 13. • A stimuli-sensitive or smart polymer undergoes an abrupt change in its physical properties in response to a small environmental stimulus • These polymers are also called as intelligent polymers because small changes occurs in response to an external trigger until a critical point is reached, and they have the ability to return to their original shape after trigger is removed • The exclusivity of these polymers lies in their nonlinear response triggered by a very small stimulus and which produces a noticeable macroscopic alterations in their structure • These transitions are reversible and include changes in physical state, shape and solubility, solvent interactions, hydrophilic and lipophilic balances and conductivity • The driving forces behind these transitions include neutralization of charged groups by the addition of oppositely charged polymers or by pH shift, and change in the hydrophilic/lipophilic balance or changes in hydrogen bonding due to increase or decrease in temperature • The major benefits of smart polymer-based drug delivery systems includes reduced dosing frequency, ease of preparation, maintenance of desired therapeutic concentration with single dose, prolonged release of incorporated drug, reduced side effects and improved stability smart polymer continue….
- 14. • These stimuli can be subsumed into discrete classifications of physical or chemical nature • Physical stimuli (i.e., temperature, ultrasound, light, and magnetic and electrical fields) directly modulate the energy level of the polymer/solvent system and induce a polymer response at some critical energy level. • Chemical stimuli (i.e., pH, redox potential, ionic strength, and chemical agents) induce a response by altering molecular interactions between polymer and solvent (adjusting hydrophobic/hydrophilic balance) or between polymer chains (influencing crosslink or backbone integrity, proclivity for hydrophobic association, or electrostatic repulsion) Stimuli
- 15. Various smart polymeric drug delivery systems
- 16. smart polymeric drug delivery systems continue…..
- 17. • These types of polymers have either an acidic or basic group in their architectural configuration, which in response to an environmental change accepts or donates a proton • The pH-sensitive polymers have the ability to release the drug either in the intestine or stomach for therapeutic response generation • Materials may swell, collapse or change depending on the pH of their environment due to the presence of functional groups in the polymer chain • These polymers can be designed with many different architectures for different applications. Key uses of pH sensitive polymers are controlled drug delivery systems, biomimetics, micromechanical systems, separation processes, and surface functionalization • pH sensitive polymers can be broken into two categories: those with acidic groups (such as -COOH and -SO3H) and those with basic groups (-NH2). The mechanism of response is the same for both, only the stimulus varies. The general form of the polymer is a backbone with functional "pendant groups" that hang off of it. When these functional groups become ionized in certain pH levels, they acquire a charge (+/-) pH-SENSITIVE POLYMERS
- 18. • Eudragit E is Food and Drug Administration (FDA) approved polymer with solubility under pH 5. The microspheres prepared by Eudragit E, of the drug donepezil, showed suppressed drug release in phosphate buffer at pH 7.4, which led to masking the bitter taste • Eudragit E is also recognized for coating of tablets for taste masking, for example, atorvastatin • Other polymers like Eudragit L, S, and F are responsive to intestinal high pH and can be used for colonic drug delivery and prevent degradation of the drug from the gastric region • Beads of rabeprazole coated with Eudragit L are known to suppress the release of drug at low pH • The pH-sensitive polymers like polypropylacrylic acid (PPAA) and polymethacrylic acid (PEAA) are used in carrying genes. The hemolytic performance of these polymers is increased when pH value is decreased ranging from pH value 5 to 6 and does not show any hemolytic activity if pH is 7.4 • Another example of pH-sensitive polymer approach is the development of micelles with the help of copolymers PEG-poly(aspartame hydrazine doxorubicin) which helps in retaining the drug and genes at physiological pH and the drug is released at pH below 6 PH-SENSITIVE POLYMERS- Examples
- 19. Scheme of synthesis of a gene delivery through pH sensitive approach Example: The polymer dimethyl aminoethyl methacrylate (DMAEMA) nanoparticles release DNA at low endosomal pH Gene delivery through pH sensitive approach
- 20. pH sensitive polymers: Examples and Properties
- 21. pH sensitive polymers: Examples and Properties
- 22. pH sensitive polymers: Examples and Properties
- 23. • The polymers that are sensitive to temperature change, that is, those whose properties are changed due to temperature, are referred to as temperature sensitive polymers • There occurs a change in the internal adjustments of polymers, the main properties of which are their lower critical solution temperature (LCST), which can make them either insoluble or soluble. This property is also responsible for phase transition from an isotropic state to anisotropic state • The polymers with low LCST are widely used in drug delivery systems because they show uniform mixing property and this helps in administering them to the human body via injection to the damaged area, where they form a gelled deposit. This makes the system deliver the drug in a controlled manner • Poly (N-isopropyl acrylamide) is a type of synthetic temperature sensitive polymer that is mostly used in drug delivery systems and shows solubility in water at room temperature. The temperature sensitive polymers can also make some hydrophobic drugs soluble to produce a proper formulation with low soluble drugs TEMPERATURE SENSITIVE POLYMERS
- 24. At a particular temperature, the phase transition takes place resulting in an alteration in polymer change and promotion in drug delivery Temperature sensitive phase transition takes place
- 26. • Ion exchange polymers possess a polystyrene backbone and side chains of ion-active precursors • The ion exchange resins are promising candidates to form drug-resin complexes for drug delivery in the form of tablets, liquid orals, and beads • These complexes release the drug into GIT and saliva due to the presence of activating ions. Also, ion exchange polymers are known to have taste masking properties • Drug loading in ion exchange polymers is carried out with complexation and due to electrostatic interactions between drug and polymers. The drug release from the polymers is ruled by the equilibrium reaction that occurs in the presence of counter-ions when they come into contact with the solution • For example, PEAA-base ion exchange polymer was used for taste masking of pseudoephedrine in chewable tablets to mask its bitter taste; due to low cation percentage in saliva than gastric fluids the drug release is minimized in saliva for masking the taste ION EXCHANGE POLYMERS