Review article

LIPID POLYMER BASED NANO PARTICLES FOR THE TREATMENT OF ULCERATIVE COLITISK.VENKATA GOPAIAH*, B.SHRISTAVA, PANKAJ KUMAR SHARMA G.SUDHAKARA RAO                    RESEARCH SCHOLAR PROFESSOR PROFESSOR PRINCIPAL & PROFESSORJAIPUR NATIONAL. JAIPUR NATIONAL JAIPUR NATIONAL VISHWA BHARATHI COLLEGE OF UNIVERSITY UNIVERSITY UNIVERSITY. PHARMACEUTICAL SCIENCESJAIPUR, RAJASTHAN JAIPUR, RAJASTHAN JAIPUR, RAJASTHAN GUNTUR-A.P

Abstract: Conventional treatment of inflammatory bowel disease is based on the daily administration of high doses of immune-suppressant or anti-inflammatory drugs, is very complicated by serious adverse effects. A carrier system that delivers the drug specifically to the inflamed intestinal regions and shows prolonged drug release would be desirable. It may enter any portion of the gastrointestinal tract though it is mostly found in the terminal ileum often with extension into the cecum and sometime into the ascending colon. Half of the cases, multiple areas of both small and large intestine are involved in segmental fashion i.e. lengths of normal intestine separate areas of disease called skip area. Crohn’s disease granulomatous colitis. Lesions of the small and large bowels are associated with anal lesions it is the first manifestation of the disease Inflammatory bowel disease is mostly common in western countries and in some areas of northern latitude. Polymeric nanoparticles can increase the permeability of an ulcerative colitis through biological barriers, such as the mucosal barriers, skin barriers and cell membrane barrier. The conventional treatments are mostly restricted to control inflammations. However, the main Aim of clinical ulcerative colitis therapy is to not only to control inflammation, but also to achieve mucosal healing. Therefore, the novel therapeutic strategies are urgently needed for addressing the limitations of existing treatments will Increase the stability of any of the volatile pharmaceutical agents, easily and also can be cheaply fabricated in large quantities by a multitude of methods. Delivers a higher concentration of pharmaceutical agent to a desired location.

Key words: Dissociation of the drug molecules from the bounded polymer (or) release from the swelled nanoparticles is observed very clearly.

INTRODUCTIONHistoryThe word ulcerative colitis was first referred in the year 1859 by sir .Samuel wilks .in the1756 Charles ,predator of the throne is suffered from ulcerative colitis but is treated by avoiding the milk food in diet .Than the clinical and biological studies if ulcerative colitis done by wilks.Statistical Data for Ulcerative ColitisInflammatory bowel disease is most prevalent in western countries and in areas of northern latitude. The reported rates of inflammatory bowel disease are highest in Scandinavia, Great Britain and North America. Crohn’s disease has an incidence of 3.6-8.8 per 100,000 persons in the United States and a prevalence of 20-40 per 100,000 people (12, 13). The incidence of Crohn’s disease varies considerably among studies, but has clearly increased dramatically over the last 3 or 4 decades. Ulcerative colitis incidence ranges from 3-15 cases per 100’000 persons per year among the while population with a prevalence of 80 to 120 per 100,000. The incidence of ulcerative colitis has remained relatively constant over many years. Although most epidemiologic studies combined ulcerative proctitis with ulcerative colitis, 17% to 49% of cases are classified as proctitis. Both sexes are affected equally with inflammatory bowel disease, although some studies show slightly greater numbers of women’s with Crohn’s disease and males with ulcerative colitis. Ulcerative and Crohn’s disease have bimodal distributions in age of initial presentations. The peak incidence occurs in the second or third decades of life, with a second peak occurring between 60&80 years of age.Classification of Inflammatory Bowel Disease

I. 5-amino salicylic acid (5-ASA) compounds Sulfasalazine (salicylazo sulfapyridine)

II. Corticosteroids Prednisolone Methyl prednisolone Triamcinolone Hydrocortisone dexamethasone

III. Immunosuppressant Tacrolimus, Azathioprine, Cyclosporine, prednisolone

IV. TNF α-Inhibitor Etanercept Infliximab Adalimunab

Nanotechnology Nanotechnology is the science and engineering carried out in the Nano scale i.e. 10 -9 m Nanoparticles are solid colloidal particles ranging in size 10-1000nm and consist of a polymeric macromolecular material which can be of synthetic or natures. A nanotechnology deal with developing materials, devices, or other structures consists of at least one dimension size ranges from 1 to 100 nano meters. Nanotechnology may be able to create many new materials and devices with a high range of applications in medicine, electronics, biomaterials and energy production. Nanotechnology is a multidisciplinary scientific field undergoing explosive development Nanoparticles have been developed as an important strategy to deliver conventional drugs, recombinant proteins, vaccines and most recently nucleotides. Heterogeneous catalysts were among the first examples, developed in 19 th century. This technology also includes photographic processes that rely on finely divided silver halide. In the Pharmaceutical field, the term nanoparticle has been rather loosely applied to structures less than 1Bm in diameter. They can be produced by either chemical or mechanical means. Other effects are tissue or cell specific targeting of drugs and reduction of unwanted side effects by a controlled release.1. Nanotechnology: Nanotechnology is the engineering of functional systems at the molecular scale. This covers both current work and concepts

that are more advanced work.2. Nanoparticles: A particle having one or more dimensions of the order of 100nm or less.3. Nano capsules: Nano capsules are vesicular systems in which the drug is confined to a cavity surrounded by a unique polymeric membrane. The

targeting of nano capsules to sites other than Reticule Endothelial System (RES) presents an important challenge to improve bioavailability of the drug associated with nano capsules.

4. Nano spheres: Nano spheres are matrix systems in which the drug is dispersed throughout the particles.5. Nano suspensions: Nano suspensions consist of pure poorly water soluble drug without any matrix material suspended in dispersion. It is sub-mi-

cron colloidal dispersion of pure particles of drug stabilized by surfactants.6. Nano crystals: The micro particles are subjected to pearl milling and the resulting particles are suspended in a surfactant solution are called as

Nano crystals. Particle size range for different Nanotechnology techniques

S.No Technique Size range1 Nanoparticles 10 to 1000 nm2 Liposome’s 15nm to several nm3 Micelles 10 -80 nm4 Solid lipid nanoparticles 50nm to 1000 nm5 Nano emulsion 50nm to 1000 nm6 Lipid Nano capsule Less than 100 nm7 Nano crystals 10 to 400 nm

Nanoparticles are small colloidal particles ,which are made of non-biodegradable and biodegradable polymers .their diameter is generally around 200nm .they are distinguished into two types ; they are nanospheres –which are matrix system and Nano capsules-which are reservoir systems composed of a polymer membrane surrounding an oil or aqueous core .Nano spheres-in this whole particle consist of a continuous polymer network .Nanocapsules-present a core cell structure with a liquid core surrounded by a polymer cell .These systems were developed in the early 1970s.This approach was attractive because the method of preparation of particles were simple and easy to scale-up. The particles formed were stable and easily freeze –dried .Due to these reasons nanoparticles made of biodegradable polymers were developed for drug delivery. Indeed, nanoparticles were able to achieve with success tissue targeting of many drugs (antibiotics, cytostatic, peptides, and proteins nucleic acids. etc.). In addition, nanoparticles were able to protect drugs against chemical and enzymatic degradation and were also able to reduce side effects of some active drugs. This review focuses on the preparation and characterization method of nanoparticles. The main applications of these systems are also described A Nanoparticle is a microscopic particle whose size is measured in nanometers (nm). It is defined as a particle with at least one dimension <200nm.or nanoparticles are solid colloidal particles ranging in size from 10nm to 1000nm. Nanoparticles (NP) have been studied extensively as particulate carriers in several pharmaceutical and medical fields. Nanoparticles, in can be used to provide targeted (cellular/tissue) delivery of drugs, to sustain drug effect in target tissue, to improve oral bioavailability to solubilize drugs for intra-vascular delivery and to improve the stability of therapeutic agents against enzymatic degradation. Nanoparticles represent very promising carrier system for the targeting of anti- cancer agents to tumors. Nanoparticles exhibit a significant tendency to accumulate in a number of tumors after iv injection. Nanoparticles can also be used in Brain Drug Targeting. Poly (butyl cyanoacrylate) nanoparticles represent the only nanoparticles that were so far successfully used for in vivo delivery of drugs to brain. Need of Nanoparticles Drug Delivery

Conventional drug therapy in tumor is associated with problems of drug intolerance and toxicity leading to permanent damage in certain or-gans.

The long duration of therapy and the drug related toxicity are common causes for non-compliance resulting in multi-drug resistant tuberculo-sis. .

Need to develop drug delivery forms that can be directly administered to the lungs as Nano particulate to reduce the systemic side effects as-sociated with the present anti-cancer drugs.

Nanoparticles of pulmonary surfactant can be employed as delivery agents for the anti-cancer drugs to the infected lung tissue. High stability. High carrier capacity. Feasibility of incorporation of both hydrophilic and hydrophobic substances, and feasibility of variable routes of administration

Advantages of nanotechnology techniques Nanotechnology-based delivery systems can also protect drugs from degradation. Longer shelf-stability High carrier capacity Ability to incorporate hydrophilic and hydrophobic drug molecules Can be administered via different routes Longer clearance time Ability to sustain the release of drug Can be utilized for imaging studies Targeted delivery of drugs at cellular and nuclear level Development of new medicines which are safer Prevent the multi-drug resistance mediated efflux of chemotherapeutic agents Product life extension Improved products may be available with a change in the physical properties when their sizes are shrunk. Reduction of dose. Make treatment a better experience and reduce treatment expenses. Nano-based systems allow delivery of insoluble drugs. Drug targeting can be achieved by taking advantage of the distinct pathophysiological features of diseased tissues. An ideal targeting system should have long circulating time; it should be present at appropriate concentrations at the target site. It should not lose its activity or therapeutic efficacy while in circulation. Tumors allow an enhanced permeability and retention effect. Passive targeting of drugs to the macrophages present in the liver and spleen. Improve the oral bioavailability of the agents that are not effectively used orally

Disadvantages of Nanoparticles Involves higher manufacturing costs which may in turn lead to increase in the cost of formulation. Involves use of harsh toxic solvents in the preparation process May trigger immune response and allergic reactions Extensive use of poly (vinyl alcohol) as stabilizer may have toxicity  issues

Applications Cancer therapy Intracellular targeting Prolonged systemic circulation Vaccine adjuvant Perioral absorption Ocular delivery

Classification of Nanoparticles i) Polymeric Nanoparticles

Polymeric nanoparticles are nanoparticles which are prepared from polymers. The drug is dissolved, entrapped, encapsulated or attached to a nanoparticles and depending upon the method of preparation,

nanoparticles, nanospheres or nanocapsules can be obtained. Nanocapsules are vesicular systems in which the drug is confined to a cavity surrounded by a polymer membrane, while

nanospheres are matrix systems in which the drug is physically and uniformly dispersed. As name only suggest polymeric nano-

particles are nanoparticles which are prepared from polymers. The drug is dissolved, entrapped, encapsulated or attached to nano-particles and depending upon the method of preparation.

Polymeric Nanoparticles are mainly two types:

Nanocapsules are vesicular systems in which the drug is confined to a cavity surrounded by a polymer membrane. Nanospheres are matrix systems in which the drug is physically and uniformly dispersed.

Need of Polymeric Nanoparticles for Ulcerative Colitis: Polymeric nanoparticles can increase the permeability of an ulcerative colitis through biological barriers, such as the mucosal barriers, skin

barriers and cell membrane barrier. Biocompatible and biodegradable. Non toxic Water soluble They are easy to synthesize, inexpensive.

The conventional treatments are mainly restricted to control inflammation. However, the main goal of clinical ulcerative colitis therapy is to not only control inflammation, but also achieve mucosal healing. Therefore, novel therapeutic strategies are urgently needed to address the limitations of existing treatments. Polymeric Nanoparticles:

The polymeric nanoparticles (PNPS) are prepared from biocompatible and biodegradable polymer in size between 10-1000 nm where the drug is dissolved, entrapped, encapsulated or attached to a nanoparticle matrix. Depending upon the method of preparation nanoparticles, nanospheres or nanocapsules can be obtained. Nanocapsules are systemic in which the drug is confined to a cavity surrounded by a unique polymer membrane, while nanospheres are matric system in which the drug is physically and uniformly dispersed. The field of polymer nanoparticles (PNPS) is quickly expanding and playing an important role in a wide spectrum of areas ranging from electronics, photonics, conducting materials, sensors, medicine, biotechnology, pollution control and environmental technology. PNPS are promising vehicles for drug delivery by easy manipulation to prepare carriers with object of delivering the drugs to specific target; such an advantage improves the drug safety. Polymer- based nanoparticles effectively carry drugs, proteins, and DNA to target cells and organs. Their nanometer-size promotes effective permeation through cell membranes and stability in the blood stream. Polymers are very convenient materials for the manufacture of countless and varied molecular designs that can be integrated into unique nanoparticles construct with many potential medical applications Advantages of Polymeric Nanoparticles:

Increase the stability of any volatile pharmaceutical agents, easily and cheaply fabricated in large quantities by a multitude of methods. They offer a significant improvement over traditional oral and intravenous method of administration in terms of efficiency and effectiveness. Delivers a higher concentration of pharmaceutical agent to a desired location. The choice of polymer and the ability to modified drug release from polymeric nanoparticles have made them ideal candidates for cancer

therapy, delivery of vaccines, contraceptives and delivery of targeted antibiotics. Polymeric nanoparticles can be easily incorporated into other activities related to drug delivery, such as tissue engineering.

Mechanism of Drug Release The polymeric drug carriers deliver the drug at the tissue site by any one of the three general physico-chemical mechanisms.1. By the swelling of the polymeric nanoparticles by hydration followed by release through diffusion.2. By an enzymatic reaction resulting in rupture or cleavage or degradation of the polymer at site of delivery, there by releasing the drug from

the entrapped inner core.3. Dissociation of the drug from the polymer and its de-adsorption / release from the swelled nanoparticles (46-48).

Preparation of NanoparticlesConventionally, NPs have been prepared mainly by two methods:

i) Dispersion of the preformed polymersii) Polymerization of monomers.

Dispersion of Preformed Polymers

Several methods have been suggested to prepare biodegradable NPs from PLA, PLG, PLGA and poly (€-caprolactone) by dispersing the preformed polymers.

Emulsification Diffusion Method Preparation of drug loaded nanoparticles was prepared by emulsification diffusion method (49-50). Polymer and drug was dissolved in ethyl

acetate. add the above solution to aqueous phase containing surfactant and emulsified by homogenization using homogeniser (20000rpm\10min) .add large volume of water to the emulsion and gentle stirring with magnetic bar, allow the ethyl acetate to leave the drop lets (51, 52) .The organic solvents and a part of water were removed by evaporation under reduced pressure for 3 hours to get purified and concentrated suspension. Final product was obtained by centrifugation (12000rpm\20min), re-dispersion and freeze drying (53, 54, 55).

Solvent Evaporation Method

In this method, the polymer is dissolved in an organic solvent like dichloromethane, chloroform, or ethyl acetate. The drug is dissolved or dispersed into the preformed polymer solution, and this mixture is then emulsified into an aqueous solution to make an oil (O) in water (W) i.e., O/W emulsion by using a surfactant for emulsifying agent like gelatine poly(vinyl alcohol) poly sorbet 80 poloximer 188 etc (56,57).After the formation of stable emulsion, the organic solvent is evaporated either by increasing the temperature/under pressure or continuous stirring the effect of process variables on the properties of NPs was discussed earlier .The W/O/W method has been also used to prepare the water soluble drug –loaded NPs. Both the methods use a high-speed homogenization or sonication. However, these procedures are good for a laboratory-scale operation, but for a large –scale pilot production, alternative methods using low –energy emulsification are required. In this pursuit, following approaches have been attempted

Schematic Representation of the Solvent-Evaporation Technique

Spontaneous Emulsification/Solvent Diffusion Method

In a modified version of the solvent evaporation method. The water –soluble solvent like acetone or methanol along with the water insoluble organic solvent like dichloride methane or chloroform were used as an a oil phase due to the spontaneous diffusion of water-soluble solvent (acetone or methanol) an interfacial turbulence is created between two phases leading to the formation of smaller particles. As the concentration of water –soluble solvent (acetone) increases, considerable decreases in particle size can be achieved.

Schematic Representation of the Emulsification/Solvent Diffusion Technique

Salting Out /Emulsification –Diffusion Method

The methods discussed above require the use of organic solvents, which are hazardous to the environment as well as to the physiological system. The USFDA has specified the residual amount of organic solvents in injectable colloidal system. In order to meet these requirements, Allemann and co-workers have developed two methods preparing NPs. The first one is a salting –out method. While the second one is the emulsification –solvent diffusion technique (61-64).

Schematic Representation of the Salting Out TechniqueProduction of Nps Using Supercritical Fluid Technology

Production of NPs with the desired physico chemical properties to facilities the targeted drug delivery has been a topic of renewed interested in pharmaceutical industry. Conventional methods like solvent evaporation, coacervation and in situ polymerization often require the use of toxic

solvent and /or surfactant. Therefore, research efforts have been directed to develop the environmentally safer en-capsulation methods to produce the drug –loaded micron and sub-micron size particles. If solvent impurities remain in the drug-loaded NPs, then these become toxic and may degrade the pharmaceutical with in the polymeric matrix. Supercritical fluid have now became the attractive alternatives because these are environmentally friendly solvents and the method can be profitably use to process particles in high purity and without any trace amount of the organic solvent. Literature on the production of drug-loaded microparticlas using supercritical fluids enormous. However comparatively much less has been investigated to produce NPs.It is beyond the scope of the present review to give an entire coverage supercritical fluid technology; we will discuss only two of the most commonly used methods of producing micro or nanoparticles

Experimental Set-Up for the Rapid Expansion of Supercritical Fluid Solution into Liquid Solvent Process

In the rapid expansion of supercritical solution (RESS) method the solute of interest is solubilised in a supercritical fluid and the solution is

expanded through a nozzle. Thus, the solvent power of supercritical fluid dramatically decreases and the solute eventually precipitates. This technique is clean because the precipitated solute is completely solvent free. Unfortunately, most polymers exhibit little or no solubility in supercritical fluid, thus making the technique less of practical interest.Ress was very popular in late 80s and early 90s for particle production of bio erodible drug-loaded polymers like PLA. A uniform distribution of drug inside the polymer matrix can be achieved by this method for low molecular mass (<10 000) polymers. However, the RESS method cannot be used for high molecular mass polymer due to their limited solubility in supercritical fluids. For these reasons, much less information is found in the literature over the past 6-7 years on this technique. In the supercritical anti-solvent (SAS) method, the solution is charged with the supercritical fluid in the precipitation vessel containing solute of interest in an organic solvent. At high pressures, enough anti-solvent will enter into the liquid phase so that the solvent power will be lowered and the solute precipitates. After precipitation, when the final operating pressure is reached, the anti-solvent flows through the vessel so as to strip the residual solvent. When the solvent content has been reduced to the desired level, the vessel is depressurized and the solid product is collected. In a modified version of the SAS technique, the solid of interest is first dissolved in a suitable solvent and then this solution is rapidly introduced into the supercritical fluid through a narrow nozzle .The supercritical fluid completely extracts the solvent, causing the supercritical fluid insoluble solid to precipitate as fine particles. This method, also called as gas anti-solvent (GAS) technique, has been successfully used to produce micro particles as NPs.

Experimental Set-Up for Preparation of Polymer Nanoparticles By Rapid Expansion of Supercritical Fluid Solution

NanoprecipitationNanoprecipitation is also called solvent displacement method. It involves the precipitation of a preformed polymer from an organic solution

and the diffusion of the organic solvent in the aqueous medium in the presence or absence of a surfactant. The polymer generally PLA, is dissolved in a water- miscible solvent of intermediate polarity, leading to the precipitation of nanospheres (69-70).This phase is injected into a stirred aqueous solution

containing a stabilizer as a surfactant. Polymer deposition on the interface between the water and the organic solvent, caused by fast diffusion of the solvent, leads to the instantaneous formation of a colloidal suspension.To facilitate the formation of colloidal polymer particles during the first step of the procedure, phase separation is performed with a totally miscible solvent that is also a non solvent of the polymer ( 71-74). The solvent displacement technique allows the preparation of nanocapsules when a small volume of nontoxic oil is incorporated in the organic phase. Considering the oil-based centre cavities of the nanocapsules, high loading efficiency are generally reported for lipophilic drugs when nanocapsules are prepared. The usefulness of the simple technique is limited to water- miscible solvent, in which the diffusion rate is enough to produce spontaneous emulsification ( 45,46).Then, even though some water-miscible solvent produce certain instability when mixed in water, spontaneous emulsification is not observed if the coalescence rate of the formed droplets is sufficiently high. Although, acetone /dichloromethane (ICH, class 2) are used to dissolve and increase the entrapment of drugs, the dichloromethane increases the mean particle size and in considered toxic (75, 76). This method is basically applicable to lipophilic drug because of the miscibility of the solvent with the aqueous phase, and it is not an efficient means to encapsulation water –soluble drugs. This method has been applied to various polymeric materials such as PLGA, PLA, PCL and poly(methyl vinyl ether-co-maleic anhydride) (PVM/MA).This technic was well adapted for the incorporation of cyclosporine A, because entrapment efficiency as high as 98% were obtained highly loaded nanoparticulate systems based on amphiphilic cyclodextrins to facilities the parenteral administration of the poorly soluble anti-fungal drugs Bifonazole and clotrimozole were prepared according to the solvent displacement method(77-79).

Schematic Representation of the Nanoprecipitation TechniqueDialysis

Dialysis offers a simple and effective method for the preparation of small, narrow –distributed NP .Polymer is dissolved in an organic solvent and placed inside a dialysis tube with proper molecular weight cut off. Dialysis is performed against a non- solvent miscible with the former miscible. The displacement of the solvent inside the membrane is followed by the progressive aggregation of polymer due to a loss of solubility and the formation of homogeneous suspensions of nanoparticle. The mechanism of PNP formation by dialysis method is not fully understood at present. It is thought that it may be based on mechanism similar to that of Nano precipitation proposed by the fessi et al .A number of polymer and copolymer nanoparticles were obtained by this technique. Poly (benzyl-l-glutamate)-b-poly (ethylene oxide), poly (lactide)-b-poly (ethylene oxide) nanoparticles were prepared using DMF as the solvent. The solvent used in the preparation of the polymer solution affect the morphology and particle size distribution of the nanoparticles. Chronopoulou et all.

Schematic Representation of Osmosis Based Method for Preparation of Polymer Nanoparticles

Reported a novel osmosis based method for the preparation of various natural and synthetic PNP.It is based on the use of a physical barrier, specifically dialysis membrane or common semi permeable membranes that allow the passive transport of solvents to slow down the mixing of the polymer solution with a non-solvent; the dialysis membrane contains the solution of the polymer.

Polymerization of MonomersTo attain the desired properties for a particular application, suitable polymer nanoparticles must be designed, which can be done during the

polymerization of monomers. Processes for the production of PNPs through the polymerization of monomers are discussed below.Interfacial Polymerization

It is one of the well- established methods used for the preparation of polymer nanoparticles It is involves step polymerization of two reactive monomers or agents, which are dissolved respectively in two phases (i.e., continues-and dispersed-phase), and the reaction takes place at the interface of

the two liquids. Nanometer-size hollow polymer particles were synthesized by employing interfacial cross-linking reaction as poly addition and poly condensation or radical polymerization. Oil – containing nanocapsules were obtained by the polymerization of monomers at the oil/water interface of a very fine oil-in-water micro-emulsion The organic solvent, which was completely miscible with water, served as a monomer vehicle and the interfacial polymerization of the monomer was believed to occur at the surface of the oil droplets that formed during emulsification. To promote nanocapsules formation, the use of aprotic solvents, such as acetone and acetonitrile was recommended. Protic solvents, such as ethanol, n-butanol and isopropanol, were found to induce the formation of the Nanospheres in addition to nanocapsules. Alternatively, water- containing nanocapsules can be obtained by the interfacial polymerization of monomers in water- in-oil micro-emulsions. In these systems the polymer formed locally at the water-oil interface and precipitated to produce the nanocapsules shell Emulsion Polymerization

Emulsion polymerization is one of the fastest methods for nanoparticle preparation and is readily scalable. The method is classified into two categories, based on the use of an organic or aqueous continues phase. The continues organic phase methodology involves the dispersion of monomer into an emulsion or inverse microemulsion, or into a material in which the monomer is not soluble (non-solvent).polyacrylamide Nanospheres were produced by this method As one of the first methods for production of nanoparticles, surfactant or protective soluble polymers were used to prevent aggregation in the early stages of polymerization. This procedure has become less important, because it requires toxic organic solvents, surfactants, monomers and initiator; which are subsequently eliminated from the formed particles. As a result of the non biodegradable nature of this polymer as well as the difficult procedure, alternative approaches are of greater interest. Later, poly (methylmethacrilate) nanoparticles were produced by dispersion via surfactants into solvents such as cyclohexane [ICH, class 2], n-pentane (ICH, class 3), and toluene (ICH, class 2) as the organic phase. In the aqueous continuous phase the monomer is dissolved in a continuous phase that is usually an aqueous solution, and the surfactants or emulsifiers are not needed. The polymerisation process can be initiated by different mechanisms initiation occurs when a monomer molecule dissolved in the continuous phase collides with an initiated molecule that might be an ion or a free radicals.Alternatively,the monomer molecule can be transformed into an initiating radical by high-energy radiation,including g-radiation, or ultra violet or strong visible light.chain growth starts when initiated monomer ions are monomer radicals collide with other monomer molecules according to an anionic polymerisation mechanism.Phase separation and formation of solid particles can take place before or after termination of the polymerisation reaction

Mini-Emulsion PolymerisationPublications on the mini-emulsion polymerisation and the development of a wide range of useful polymer materials have recently increased

substantially.A typical formulation used in mini-emulsion polymerisation consist of water,monomer mixture,co-stabilizer,surfactant,and initiator.The key differences between emulsion polymerisation and mini-emulsion polymerisation is the utilization of a low molecular mass compound as the co-stabilizer and also the use of a high-shear device (ultrasound,etc).Mini-emulsions are critically stabilized,require a high shear to reach a study state and have an interfacial tension much greater than zero.The various polymer nanoparticles were prepared by using mini-emulsion method as discussed in the literature

Micro- Emulsion Polymerisation

Micro-emulsion polymerisation is a new and effective approach for preparing nonosized polymer particles and has attracted significant attention. Although emulsion and micro-emulsion polymerisation appear similar because both method can produce colloidal polymer particle of high molar mass, they are entirely different when compared kinetically. Both particle size and the average number of chains per particle are considerably smaller in micro-emulsion polymerisation. In micro-emulsion polymerisation, an initiator, typically water-soluble, is added to the aqueous phase of a thermodynamically stable micro-emulsion containing swollen micelles. The polymerisation starts from this thermodynamically stable, spontaneously formed state and relies on high quantities of surfactant systems, which posseses an interfacial tension at the oil/water interface close to zero. Further more,the particles are completely covered with surfactant because of the utilization of a high amount of surfactant.Initially,polymer chains are formed only in some droplets, as the initiation cannot be attained simultaneously in all micro droplets.Later,the osmotic and elastic influence of the chains destabilize the fragile micro-empty micelles, and secondary nucleation. Very small latexes, 5-50nm in size, coexist with a majority of empty micelles in the final product. The types of initiator and concentration, surfactant, monomer and reaction temperature are some of the critical factors affecting the micro-emulsion polymerisation kinetics and the properties of PNP.

Ionic Gelation or Conservation of Hydrophilic PolymersPolymeric nanoparticles are prepared by using biodegradable hydrophilic polymers such as chitosan, gelatin and sodium alginate. Calvo and

co-workers developed a method for preparing hydrophilic chitosan nanoparticles by ionic gelation. Amir Dustgani et al prepared Dexamethasone sodium phosphate loaded chitosan nanoparticles by ionic gelation method. The method involves a mixture of two aqueous phases, of which one is the polymer chitosan, a di-block co-polymer ethylene oxide or propylene oxide (PEO-PPO) and the other is a poly anion sodium tri poly phosphate. In this method, positively charged amino group of chitosan interacts with negative charged tri poly phosphate to form coservates with a size in the range of nanometer. Coservates are forms as a result of electrostatic interaction between to aqueous phases, whereas ionic gelation involves the material undergoing transition from liquid to gel due to ionic interaction conditions at room temperature

Schematic Representation of Ionic Gelation Method

Controlled/Living Radical Polymerization(C/LRP)The primary limitations of radical polymerization include the lack of control over the molar mass, the molar mass distribution, the end

functionalities and macromolecular architecture. The limitations are caused by the unavoidable fast radical-radical termination reaction. The recent emergence of many so-called controlled or ‘living` radical polymerization (C/LRP) processes has opened a new area using an old polymerization technique. The most important factors contributing to this trend of the C/LRP process are increased environmental concern and a sharp growth of pharmaceutical and medical applications for hydrophilic polymers. These factors have given rise to "green chemistry "and created a demand for environmentally and chemically benign solvents such as water and supercritical carbon dioxide. Industrial radical polymerization is widely performed in aqueous dispersed systems and specifically in emulsion polymerization. The primary goal was to control the characteristic of the polymer in terms of molar mass, molar mass distribution, architecture and function. Implementation of C/LRP in the industrially important aqueous dispersed systems, resulting in the formation of polymeric nanoparticles with precise particle size and size distribution control, is crucial for future commercial success of C/LRP. Among the available controlled / living radical polymerization methods successful and extensively studied methods are

1) Nitrox ide –mediated polymerization( NMP2) Atom transfer radical polymerization (ATRP)

The nature and concentration of the control agent, monomer, initiator and emulsion type (apart from temperature) are vital in determining the size of PNPs. Of these, the nature of the control agent is critical in determining the particle size of the final product.Characterization Studies Drug Loaded Nanoparticles:Determination of Particle Size

The mean particle size and size distribution analysis of nanoparticles were performed by the dynamic light scattering (DLS) method at 25 0c with a 900c scattering angle for optimum detection. Ten milli grams of drug drug loaded nanoparticles was dispersed in 10 ml of deionized water. The dispersion was sonicated for 1 min and size immediately. The results shown (mean± standard deviation (SD)) are representatives of three independent. Determination of Drug Entrapment Efficiency

Drug concentrations were determined by HPLC-MS. Ten milli grams of nanoparticles containing drug were dissolved in 10 ml of methanol. The solution was stirred for 1 hrs and sonicated for 5 min. afterwards the solution was diluted with a specific volume of the mobile phase and injected into HPLC.EE was calculated with following equation: EE (%, w/w) = weight of drug in nanoparticle/weight of drug used in preparation of nanoparticles in 100.Measurement of Zeta Potential:

The zeta potential of prepared nanoparticles was measured by the ELS-8000 zeta potential analyse was triplicate among different batches to assess the surface charge and stability of nanoparticle. Zeta potential of Nano particles was measured in aqueous dispersion. The measurements were carried out using the medium of water. The results (mean ± SD) are representatives of three independent experiments.

REVIEW Kumar’s S. Soppimath et al., This review present the most outstanding contributions in the field of biodegradable polymeric nanoparticles used as drug delivery systems. Methods of preparation, drug loading and drug release are covered. The most important findings on surface modification methods as well as surface characterization are covered from 1990 through mid-2000. © 2001 Elsevier science B.V.All rights reserved.Hirenkumar K. Makadia et al., In past two decades poly lactic-co-glycolic acid has been among the most attractive polymeric candidates used to fabricate devices for drug delivery and tissue engineering applications. PLGA is biocompatible and biodegradable, exhibits a wide range of erosion times, has unable mechanical properties and most importantly, is a FDA approved polymer. In particular, PLGA has been extensively studied for the development of devices for controolled delivery of small molecule drugs, proteins and other macromolecule in commercial use and in research. This manuscript describe the various fabrication techniques for these devices and the factors affecting their degradation and drug release.VJ Mohan raj et al., for the past few decades, there has been a considerable research interest in the area of drug delivery using particulate delivery systems as carriers for small and large molecules. Particulate systems like nanoparticles have been used as a physical approach to alter and improve the pharmacokinetic and pharmacodynamics properties of various types of drug molecules. They have been used in vivo to protect the drug entity in the systemic circulation, restrict access of the drug to the chosen sites and to deliver the drug at a controlled and sustained rate to the site of action. Various polymers have been used in the formulation of nanoparticles for drug delivery research to increase therapeutic benefit, while minimizing side effects. Here, we review various aspects of nanoparticle formulation, characterization, effect of their characteristics and their applications in delivery of drug molecules and therapeutic genes.Nagavarma B V N et al., polymeric nanoparticles PNPs are defined as particulate dispersions or solid particles with size in the range of 10-1000nm. There has been a considerable research interest in the area of drug delivery using particulate delivery systems as carriers for small and large molecules. Particulate systems like nanoparticles have been used as a physical approach to alter and improve the pharmacokinetic and pharmacodynamics properties of various types of drug molecules. Polymeric nanoparticles have been extensively studied as particulate carriers in the pharmaceutical and medical fields, because they show promise as drug delivery systems as a result of their controlled and sustained release properties, subcellular size, biocompatibility with tissue and cells. Several methods to prepare polymeric nanoparticles have been developed and these techniques are classified according to whether the particle formation involves a polymerization reaction or nanoparticles form directly from a macromolecule or preformed polymer. In this review the different techniques for preparation of polymeric nanoparticles are described.A.KRISHNA SAILAJA et al., over the past three decades, there has been a considerable research interest in the area of developing drug delivery using nanoparticles (NPs ) as carriers for small and large molecules. Targeting delivery of drugs to the diseased lesions is one of the most important aspects of drug delivery system. They have been used in vivo to protect the drug entity in the systemic circulation, restrict access of the drug to the chosen sites and to deliver the drug at a controlled and sustained rate to the site of action. Chitosan is a natural polymer obtained by acetylation of chitin. After cellulose chitin is the second most abundant polysaccharide in nature. It is biologically safe, nontoxic, biocompatible and biodegradable polysaccharide. Chitosan nanoparticles have gained more attention as drug delivery carriers because of their better stability, low toxicity, simple and mild preparation method and providing versatile routes of administration.

Sae-Byeok Shin et al., in an effort to improve targeting efficiency and reduced the toxicity of tacrolimus, the emulsification-diffusion method was used to lower the drug into nanoparticle. Nanoparticles were characterized by thermal analyser and X-ray diffractometry and their shape were observed by scaning electron microscopy and transmission. Invitro release profile were affected by the PH of dissolution media the prepared nanoparticles and commercial product of tacrolimus were intra venous administered to rates to compare their pharmacokinetic characteristic and targeting efficiency these results showed that the prepared tacrolimus –loaded nano particles are good possible candidates as a lymphatic delivery system of tacrolimus.Jian Chang et al., many studies showed that transferrin increases brain delivery of nanoparticles in vivo, however the mechanism inplaied in their brain uptake are not yet clearly elucidated. In this study we evaluated the endocytosis of PLGA nanoparticle coated with transferrin on an invitro model of the blood-brain barrier (BBB) made of co-culture of brain endothelial cells and astrocytes. Protein adsorption on the surface of the nanoparticles was found to be stable for at least 12days at 370c.Studies in presence of inhibitor suggest that TF-NP interact with the cells in a specific manner and enter the cells via the caveolae pathwayObjectives:

To develop Drug loaded polymeric Nano particles and optimise the formulation parameters. To develop nanoparticles containing Drug with higher stability and better release profile. To reduce the overall dose of Drug require for ulcerative colitis treatment by loading in nano carriers. To study the physicochemical properties of Drug loaded polymeric nano particles. To study the drug release profile of prepared Nano particles.

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