“FORMULATION AND EVALUATION OF COLON TARGETED PELLETS OF BUMADIZONE CALCIUM”

Aim: The aim of this study was to Formulation and Evaluation of colon targeted pellets of Bumadizone Calcium Objective: Bumadizone Calcium is an acetic acid derivative, having irritation in stomach. Bumadizone Calcium has short half-life (4hrs) and undergoes first pass metabolism. It is pH-dependent. This research work was carried out to improve the bioavailability, patient compliance on oral colon targeted drug delivery. Bumadizone Calcium sustained release enteric coated pellets were prepared, which minimize the release of drug in stomach for treatment of IBD formulated by Extrusion Spheronization process. Experimental work done: Enteric coated pellets prepared by Extrusion Spheronization technique. Eudragit S100, HPMC, PVP K30, and Ethyl Cellulose were used as rate controlling polymers. In this study, a pH dependent colon targeted enteric coated pellets was established using 3 full factorial design by giving enteric coating with Eudragit S100. Different Concentration of Eudragit S100 as an enteric coating material (4%, 5%, & %6) and PVP K30 as a Binder (0.5%, 1% & 1.5%) are taken for the measurements of % Drug Release that are performed by using USP dissolution 1 (Basket type) at 50 rpm. The test is performed with gastric fluid (pH 1.2) at 37±0.5 for first 2 hours & then in phosphate buffer 6.8 for 4 hrs & finally in phosphate buffer pH 7.4 for 6 hrs. The prepared formulations were evaluated for drug-excipient compatibility study, flow property, drug content, and coating process efficiency. Results and Discussion: Optimized batch shown that less than 0.50% of the drug released at the end of 2 hrs in pH 1.2, less than 20% of drug released after end of 4 hrs in pH 6.8 and more than 85% at the end of 12 hrs in pH 7.4. Conclusion: Bumadizone Calcium Enteric Coated pellets can be successfully formulated by addition of PVP K30 as a binder and Eudragit S100 as Coating polymer. It was also concluded that prepared formulation minimizes drug release in stomach and avoid side effect of the drug.


Inflammatory Bowel Disease
Crohn's disease and ulcerative colitis are inflammatory bowel diseases that cause chronic inflammation and damage in the gastrointestinal (GI) tract (figure1) The GI tract is responsible for digestion of food, absorption of nutrients, and elimination of waste. Inflammation impairs the ability of affected GI organs to function properly, leading to symptoms such as persistent diarrhoea, abdominal pain, rectal bleeding, weight loss and fatigue. While ongoing inflammation in the GI tract occurs in both Crohn's disease and ulcerative colitis, there are important differences between the two diseases.  Ascending colon 20- 25 3 Descending colon 10- 15 4 Transverse colon 40-45 5 Sigmoid colon 35-40 6 Rectum 12 7 Anal canal 3

Mr. Shah Akashkumar Nareshkumar et al, Journal of Pharmaceutical and Biological Science Archive
4 | P a g e 1.2.2 Colon targeted drug delivery system (CTDDS) [7][8][9] [10] Colon targeted drug delivery system (CTDDS) maybe follow the concept of Sustained or controlled drug delivery system, for CTDDS oral route of administration has received most attention. This is because of the flexibility in dosage form designed for oral than parenteral route because, a) Patient acceptance for the oral administration of the drug is quite high. b) It is relatively safe route of drug administration compared with parenteral route and potential damage at site of administration is minimal. c) Most of the conventional drug delivery systems for treating the colonic disorder such as Inflammatory bowel diseases i.e. Ulcerative colitis, Cohn's diseases, Colon cancer and Amoebiasis are failing as drug do not reach the site of action in appropriate concentration. For effective and safe therapy of these colonic disorders, colon specific drug delivery is necessary. Today, colon specific drug delivery is challenging task to pharmaceutical technologists. d) Therapeutic advantages of targeting drug to the diseased organ include: e) The ability to cut down the conventional dose f) Reduced the incidence of adverse side effects g) Delivery of drug in its intact form as close as possible to the target sites. h) Colon specific drug delivery systems are also gaining importance for the delivery of protein and peptides due to several reasons as follow i) Rapid development of biotechnology and genetic engineering resulting into the availability of protein and peptide drugs at reasonable cost. j) Proteins and peptide drugs are destroyed and inactivated in acidic environment of the stomach or by pancreatic enzymes in small intestine. k) Parental route is expensive and inconvenient. l) Longer residence time, less peptidase activity and natural absorptive characteristics make the colon as promising site for the delivery of protein and peptide drug for systemic absorption. m) Less diversity and intensity of digestive enzymes. n) Comparative proteolytic activity of colon mucosa is much less than observed in the small intestine, i.e. CDDS protects peptide drugs from hydrolysis, and enzymatic degradation in duodenum and jejunum, and eventually releases the drug into ileum or colon which leads to higher systemic bioavailability. Azulfidine® CAP (dissolution pH 6.2-6.5) ColoPleon® Eudragit® L 100-55 (dissolution pH 5.5) ii.
Embedding in pH-sensitive matrices: -The drug molecules are embedded in polymer matrix. Extrusion Spheronization technique can be used to prepare uniform-size sturdy pellets for colon targeted drug delivery when it is not possible to obtain mechanically strong granules by other methods. Excipients had a significant impact on the physical characteristics of the pellets. Eudragit S100 as a pH sensitive matrix base in the pellets increased the pellet size and influenced pellet roundness. Citric acid promoted the pelletization process resulting in a narrower area distribution. However, Eudragit S100 could not cause statistically significant delay in the drug release at lower pH. Some market formulations Asacol® Proctor & Gamble Pharmaceuticals, USA Delayed-release tablets containing mesalazine and coated with Eudragit® S-100 are marketed in a number of countries (Asacol). These tablets dissolve at pH 7 or greater, releasing mesalazine in the terminal ileum and beyond for topical inflammatory action in the colon.  [17] Mr. Shah Akashkumar Nareshkumar et al, Journal of Pharmaceutical and Biological Science Archive 7 | P a g e 2) Time dependent delivery [18] [19] :-It also known as pulsatile release or delayed release or sigmoidal release system. This approach is based on the principle of delaying the release of the drug until it enters into the colon.

Conditions in GIT
Although gastric emptying tends to be highly variable, small intestinal transit time is relatively constant or little bit variation can be observed. The strategy in designing timed-released systems is to resist the acidic environment of the stomach and to undergo a lag time of predetermined span of time, after which release of drug take place.
The lag time in this case is the time requires to transit from the mouth to colon.
A lag-time of 5 hours is usually considered sufficient since small intestine transit is about 3-4 hours, which is relatively constant and hardly affected by the nature of formulation administered.
Time-controlled systems are useful for synchronous delivery of a drug either at pre-selected times such that patient receives the drug when needed or at a pre-selected site of the GI tract. These systems are therefore particularly useful in the therapy of diseases, which depend on circadian rhythms.

Disadvantages of this system:
Gastric emptying time varies markedly between subjects or in a manner dependent on type and amount of food intake.
Gastrointestinal movement, especially peristalsis or contraction in the stomach would result in change in gastrointestinal transit of the drug. Accelerated transit through different regions of the colon has been observed in patients with the IBD, the carcinoid syndrome and diarrhoea and the ulcerative colitis. Therefore, time dependent systems are not ideal to deliver drugs to colon specifically for the treatment of colon related diseases. Appropriate integration of pH sensitive and time release functions into a single dosage form may improve the site specificity of drug delivery to the colon. Time-dependent drug delivery includes:  Pulsincap  Time clock  Time-Controlled-Explosion Drug-Delivery System (Pulsatile System Based on Rupturable Coating)  Colon Targeted Delivery Capsule based on pH sensitivity and time-release principles  Chronotropic® system  PORT system 3) Microbially triggered drug delivery to colon [16] [18] The microflora of colon is in the range of 10 11 -10 12 CFU/mL, consisting mainly of anaerobic bacteria, e.g. Bacteroides, Bifidobacteria, Eubacteria, Clostridia, Enterococci, Enterobacteria and Ruminococcus etc.
This vast microflora fulfils its energy needs by fermenting various types of substrates that have been left undigested in the small intestine, e.g. di-and tri-saccharides, polysaccharides etc.
Because of the presence of the biodegradable enzymes only in the colon, the use of biodegradable polymers for colon-specific drug delivery seems to be a more site-specific approach as compared to other approaches.
These polymers shield the drug from the environments of stomach and small intestine and are able to deliver the drug to the colon.
On reaching the colon, they undergo assimilation by micro-organism or degradation by enzyme or break down of the polymer back bone leading to a subsequent reduction in their molecular weight and thereby loss of mechanical strength. They are then unable to hold the drug entity any longer.  [19] [20] Oral administration of some drugs requires high local concentration in the large intestine for optimum therapeutic effects. Bioadhesion is a process by which a dosage form remains in contact with particular organ for an augmented period of time. This longer residence time of drug would have high local concentration or improved absorption characteristics in case of poorly absorbable drugs. This strategy can be applied for the formulation of colonic drug delivery systems. Various polymers including polycarbophils, polyurethanes and polyethylene oxide-polypropylene oxide copolymers have been investigated as materials for bioadhesive systems. Bioadhesion has been proposed as a means of improving the performance and extending the mean residence time of colonic drug delivery systems.

5) Pressure controlled system [25][26][27]
The digestive processes within the GI tract involve contractile activity of the stomach and peristaltic movements for propulsion of intestinal contents. In the large intestine, the contents are moved from one part to the next, as from the ascending to the transverse colon by forcible peristaltic movements commonly termed as mass peristalsis. These strong peristaltic waves in the colon are of short duration, occurring only three to four times a day. However, they temporarily increase the luminal pressure within the colon, which forms the basis for design of pressure-controlled systems. The luminal pressure resulting from peristaltic motion is higher in the colon compared to pressure in the small intestine, which is attributed to the difference in the viscosity of luminal contents. In the stomach and small intestine, contents are fluidic because of abundant water in digestive juices, but in the colon, the viscosity of the content is significantly increased due to reabsorption of water from the lumen and formation of faces. It has therefore been concluded that drug dissolution in the colon could present a problem in relation to colon-specific oral drug delivery systems. Takaya et al. (1995) have developed pressure controlled colon delivery capsules prepared using an ethyl cellulose, which is insoluble in water. In such systems drug release occurs following disintegration of a water insoluble polymer capsule as a result of pressure in the lumen of the colon. The thickness of the ethyl cellulose membrane is the most important factor for disintegration of the formulation. The preferred thickness of the capsule wall is about 35-60 μm [27] . The system also appeared to depend on capsule size and density. In pressure-controlled ethyl cellulose single unit capsules the drug is in a liquid. Lag times of three to five hours in relation to drug absorption were noted when pressure-controlled capsules were administered to human.

6) Osmotic controlled drug delivery [28] [29]
The OROS-CT system can be single osmotic unit or may incorporate as many as 5-6 push-pull units, each 4mm in diameter, encapsulated within a hard gelatin capsule. Each push-pull unit is bilayered laminated structure containing an osmotic push layer and a drug layer, both surrounded by a semipermeable membrane. In principle, semipermeable membrane is permeable to the inward entry of water and aqueous GI fluids and is impermeable to the outward exit of the drug. An orifice is drilled into the semipermeable membrane to the drug layer. The outside surface of the semipermeable membrane is then coated by eudragit® S100 to delay the drug release from the device during its transit through the stomach. Upon arrival on the small intestine the coating dissolves at pH≤7. As a result, water enters the unit causing the osmotic push compartment to swell forcing the drug out of the orifice into colon. For treating ulcerative colitis, each push pull unit is designed with a 3-4 hour post gastric delay to prevent drug delivery in the small intestine. Drug release begins when the unit reaches the colon. OROS-CT units can maintain a constant release rate for up to 24 hr. in the colon or can deliver drug over an internal as short as 4 hours.

7) Multiparticulate systems [21] [22] [23] [24]
Single unit colon targeted drug delivery system may suffer from the disadvantage of unintentional disintegration of the formulation due to manufacturing deficiency or unusual gastric physiology that may lead to drastically compromised systemic drug bioavailability or loss of local therapeutic action in the colon. Report suggests that drug carrier systems larger than 200 μm possess very low gastric transit time due to physiological condition of the bowel in colitis. For this reason and considering the selective uptake of micron or submicron particles by cancerous and inflamed cells/ tissues a multiparticulate approach is expected to have better pharmacological effect in the colon. Recently, much emphasis is being laid on the development of multiparticulate dosage forms in comparison to single unit systems because of their potential benefits like,  Multiparticulate systems enabled the drug to reach the colon quickly and were retained in the ascending colon for a relatively long period of time and hence increased bioavailability.  Because of their smaller particle size as compared to single unit dosage forms these systems are capable of passing through the GI tract easily, leading to less inter and intrasubject variability.  Moreover, multiparticulate systems tend to be more uniformly dispersed in the GI tract and also ensure more uniform drug absorption.  Reduced risk of systemic toxicity, reduced risk of local irritation and predictable gastric emptying. Multiparticulate approaches tried for colonic delivery include includes formulations in the form of pellets, Granular matrix, Beads, Micro spheres, Nano particles. [32]  An enteric coating is a barrier applied to oral medication that controls the location in the digestive tract where it is absorbed. Enteric refers to the small intestine; therefore, enteric coating on the dosage form prevents the release of drug before it reaches the small intestine. Most enteric coatings work by presenting a surface that is stable to highly acidic pH of stomach, But breaks down rapidly at a less acidic (relatively more basic) pH.

Necessary Enteric coating-: 1. After Taking a Typical Supplement
 The tablet is swallowed and travels down the oesophagus to the stomach.  In the stomach the tablet is churned and gyrated in highly acidic digestive Secretions with p H (1-4), for 45 minute to 2 hours.  If there is anything left of tablet, it will be passed through the duodenum to the small intestine.

Fate of Uncoated Tablets:
 Stomach acid breaks down tablets to prematurely release active ingredients (enzyme).  The highly acidic environment of the stomach destroys the majority of the enzymes activities.  If the tablet is of poor quality (contains Binder and fillers) the product may pass through both the stomach and intestine with no absorption. [32] :

Enteric coating is suitable for
 Drugs that have irritant effect in stomach (like aspirin),  Drugs which are unstable in acidic pH of stomach.  Thus, enteric coating is aimed to prevent the formulations from gastric fluid in the stomach and  Release the drug component in the intestinal region or once it has passed into the duodenum.  Some of the most important reasons for the application of enteric coating to the dosage form are as follows:  To protect the acid-labile drugs from the acidic pH of gastric fluid. Example: enzymes and certain antibiotics.  To prevent gastric distress or nausea due to irritation caused by certain drugs. Example: Sodium salicylate.  To deliver drugs intended for the local action in intestines. Example: intestinal antiseptics could be delivered to their site of action in a concentrated form and bypass systemic absorption in the stomach.  To deliver drugs that are optimally absorbed in the small intestine to their primary absorption site in their most concentrated form.
 To provide a delayed release component to repeat action tablets.

An ideal enteric coating material should possess the following properties [30] [31] :
 Resistance to gastric fluids.  Ready susceptibility to or permeability to intestinal fluids.  Compatibility with most of the coating solution components and the drug substances.  Stability alone and in the coating solutions i.e. the film should not change upon aging.  Formation of a continuous film on the dosage form.  Non-toxic and non-irritant.  Low cost.  Ease of application without specialized equipment.  Ability to be readily printed or to allow film to be applied to debossed tablets. In agitation method, finely divided particles are converted to spherical pellets by continuous rolling or tumbling motion using a rotating drum, pan or disc. The liquid may be added prior to or during the agitation stage.

Compaction:
Particles and/or granules are forced together by mechanical force to generate pellets. Volume reduction is a common feature of this process.

i. Compression:
In this process mixtures of active ingredients and excipients are compacted under pressure to generate pellets of defined shape and size. During compression at high pressure, particles of a packed mass are forced against each other so that elastic and plastic deformation can take place and create strong interparticle contact.
ii. Extrusion &Spheronization [33,34,39,40,42] : In extrusion & spheronization process, the powder is formed into a wet mass, which is forced through restricted extrusion area to form strands of extrudates that are broken into short lengths and rounded by placement on a rotating plate with in a cylinder. The resulting spherical granules or pellets are of uniform shape, size and density.   ii. Solution / Suspension Layering [42] : Solution and Suspension Layering involve the deposition of successive layers of solution and suspension. Respectively, on the starter seeds that are inert materials or crystals or granules. Principle of solution and suspension layering given below.

Figure 9: Solution layering
Globulation: i. Spray drying [43] : In spray drying process, drug entities in solution or suspension form are sprayed, with or without excipients, into a hot-air stream to generate dry and highly spherical particles.
ii. Spray congealing [43] : In spray congealing process a drug is allowed to melt, disperse or dissolve in hot melts of gums, waxes, fatty acids etc. which further sprayed into an air chamber where the temperature going below the melting points of the formulation components, to provide, under appropriate processing conditions, spherical congealed pellets. New Techniques: 1. Cryopelletization [44] : In cryopelletization technique, droplets of a liquid formulation are converted into solid spherical particles or pellets by employing liquid nitrogen as the fixing medium. Drug-loaded pellets are produced by allowing droplets of a solution or suspension to come in contact with liquid nitrogen at -1600°C. [44] :

Melt Spheronization
In melt spheronization technique, drug substance and excipients are converted into a molten state or semimolten state and subsequently shaped using appropriate equipment to provide solid spheres or pellets.

Equipments
The equipments used for the tablet/pellet coating are as per below.

I.
Standard coating pan [45]  Also known as conventional pan system  Circular metal pan which is mounted angularly on a stand  8-60 inches in diameter  Rotated on its horizontal axis by a motor  Heated air is directed into the pan & on to the tablet/pellets bed surface and is exhausted by means of ducts through the front of the pan Coating solution are applied to the tablets/pellets by layering and/or spraying the material on to the rotating bed. Use of spraying systems- Produces faster and more even distribution of the solution and/or suspension.  Reduces drying time between solution applications in sugar coating.
 Allows continuous application of the solution in film coating.  In standard coating pan, the drying efficiency is improved by  Pellegrini pan  The immersion sword  Immersion tube systems  Rotates on horizontal axis in an enclosed housing.
 The coting solution is applied to the surface of the rotating bed of tablets through spraying nozzle, which is present inside the drum.
 Perforated pan coater providing efficient drying systems with high coating capacity.

Types of fluid bed technologies
Top spray Bottom spray Tangential spray   [46]  Odourless and tasteless, white or creamywhite fibrous or granular powder.

Typical Properties
Moisture content: -It absorbs moisture from the atmosphere. The amount of water absorbed depends upon the initial moisture content, temperature and relative humidity of the surrounding air. Solubility: It is soluble in cold water. It is practically insoluble in hot water, chloroform, ethanol (95%), and ether.

Stability and Storage Conditions
Solutions are stable at pH 3-11. It undergoes a reversible sol-gel transformation upon heating and cooling, respectively. Powder should be stored in a well-closed container and keep in a cool & dry place. Table 1

Use
Concentration (%) Suspending and/or thickening agent 0.25-5.0% As a binder with either in wet or dry granulation processes 2-5% 3. Microcrystalline Cellulose [49]  Moisture content: -less than 5% w/w. different grades may contain varying amount of water. It is hygroscopic. Solubility: slightly soluble in 5% w/v sodium hydroxide solution, Practically insoluble in water, dilute acids, and most organic solvents.

Stability and Storage Conditions
It is stable through hygroscopic material; the bulk material should be stored in a well-closed container in a cool, dry place. Freely Soluble in acids, chloroform, ethanol (95%), ketones, methanol, and water; practically insoluble in ether, hydrocarbons, and mineral oil. Dermatologists utilize acetone by alcohol used for acne treatments to peel dry skin. General agents used nowadays for chemical peels are salicylic acid, glycolic acid, Acetone or a combination of these agents is often used in this procedure. [52]  Talc is a stable material and may be sterilized by heating at 160°C for not less than 1 hour. It may also be sterilized by exposure to ethylene oxide or gamma irradiation. Talc should be stored in a well-closed container in a cool, dry place. It is white, amorphous, odorless, and tasteless, nonhygroscopic powder. Although the average particle size of titanium dioxide powder is less than 1 mm, commercial titanium dioxide generally occurs as aggregated particles of approximately 100mmin diameter. Titanium dioxide may occur in several different crystalline forms: rutile; Anatase and brookite. Among of these, rutile and anatase are only forms of commercial importance. Rutile is the more thermodynamically stable crystalline form, but anatase is the form most commonly used in pharmaceutical applications. Functional category Coating agent; opacifier; pigment Typical properties Bulk Density: 0.4-0.62 g/cm3 Melting point:-1855°C Moisture content: -0.44% Solubility: Practically insoluble in dilute sulfuric acid, hydrochloric acid, nitric acid, organic solvents, and water. Soluble in hydrofluoric acid and hot concentrated sulfuric acid. Solubility depends on previous heat treatment; prolonged heating produces a less-soluble material. Stability and storage conditions Titanium dioxide is extremely stable at high temperatures. This is due to the strong bond between the tetravalent titanium ion and the bivalent oxygen ions. However, titanium dioxide can lose small, unweighable amounts of oxygen by interaction with radiant energy. This oxygen can easily recombine again as a part of a reversible Photochemical reaction, particularly if there is no Oxidisable material available. These small oxygen losses are important because they can cause significant changes in the optical and electrical properties of the pigment. Titanium dioxide should be stored in a well-closed container, protected from light, in a cool, dry place. [55] 30), maize starch, mannitol and eudragit S-100, L-100 polymer to transport drug to colon for local treatment of ulcerative colitis. The result of two independent variables, Eudragit S100 & Eudragit L 100 and differ release was study at 12hrs. From in-vitro & in-vivo study formulation composed of (EU S100 1:3, 250 mg mannitol, 50mg maize starch and 20mg cinnamon powder) minimizes drug release in the upper gastrointestinal tract and at colon it gives highest release.  Maimana A. Magdy et al., 2013, studied stability indicating spectrophotometric methods for determination of bumadizone in the presence of its alkaline degradation product The four methods were found to be specific for determination BUM in presence of different concentrations of DEG I and had successfully applied for the determination of BUM in Octomotol tablets.  Samia A. Nour et al., 2014, studied Bumadizone calcium dihydrate microsphere were dense into tablet contain the (NSAIDS) non-steroidal anti-inflammatory. The effect of polymer Eudragit RS 100, ethyl cellulose, cellulose acetate butyrate. Candidate formula F15 (microspheres prepared using a ratio of 18:1 for BDZ:CAB and compressed into tablets using 50% pectin and 50% Avicel in the coat) was able to modulate drug release in colon by avoiding drug release in the gastric ambient, and reaching the colonic targeting where 99.7% release was achieved within 12 hrs.  Sateesh Kumar Vemula et al., 2015, studied to formulate and study the pharmacokinetics of colon-specific pulsatile ketorolac tromethamine tablets using double-compression coating method In this, inner compression coat made of sodium starch glycolate as swelling layer and outer compression coat (release controlling layer) contains sodium alginate and Hydroxypropyl methylcellulose K 15M. From the in vitro drug release studies, F5 tablets sodium starch glycolate: HPMC K15M in ratio 1:1 showed 5.02 ± 0.16% drug release in 5 h and it was progressively expanded to 99.78 ± 0.64% in 24 h that demonstrate the colon-specific drug release.  Rohit Mehta et al., 2013, studied to prepare matrix tablets of naproxen using a hydrophobic polymer, i.e., Eudragit RLPO, RSPO, and combination of both, by wet granulation method. The tablets were further coated with different concentrations of Eudragit S-100, a pH-sensitive polymer, by dip immerse method. In vitro drug release studies of tablets were carried out in different dissolution media, i.e., 0.1 N HCl (pH 1.2), phosphate buffers pH 6.8 and 7.4, with or without rat cecal content matrix tablet of naproxen was formulate with Eudragit S 100 like a pH sensitive polymer. The outcome demonstrate that the tablets coated with Eudragit S-100 show a sustain release of 94%.  Minjie Sun et al., 2014, studied to develop colon adhesive pellets of 5-aminosalicylic acid (5-ASA) for the treatment of ulcerative colitis. The core of the pellet was formulated from bioadhesive agents, Carbomer 940 and Hydroxypropyl cellulose (HPC), by extrusion/Spheronization method and coated with Surelease1 as inner layer for waterproof and with Eudragit1 S100 as outer layer for pH control Microcrystalline cellulose 101 (PH 301) was found to be the best agent for pellet core. The ratio of CP940 to HPC should be kept as (1:1) to achieve high bioadhesion. When the amount of Surelease1 was from 16% to 20% and of Eudragit S100 was 28%, the dissolution profiles of coated pellets revealed no drug release in the artificial gastric fluid (pH 1.0) within 2 hrs and less than 10% was released in phosphate buffer (pH 6.0) within 2 hrs whereas complete dissolution was observed in colonic fluid of pH 7.4 for 20 hrs.  Zan Liu et al., 2016, studied sticking of pellets caused by EudragitL30D-55 was observed during the release process, leading to change in drug release. Talcum powder (talc) was used in esomeprazole magnesium pellets to prevent sticking and modify release of pellets. Talc as antiadherent could successfully prevent the pellets from aggregating in vitro by the two methods tested: (i) physically mixed with resulted pellets and (ii) coating the resulted pellets. Besides, talc levels in sub coat had different influences on drug release from coated pellets in phosphate buffer solution (pH 6.8 and 6.0) and distilled water, attributing to the different release mechanisms of pellets in these three media. Talc could not only prevent the sticking during release process, but also affect the release of the EMZ from the enteric-coated pellets.

Triethyl Citrate
 Pranjal Kumar S et al., 2012, studied to develop colon targeted film coated tablets of ibuprofen using HPMC K4M, Eudragit L100 &Ethyl cellulose as carriers. The formulation of drug released 98.34%. & to provide targeting of ibuprofen for local action in the colon due its least release of the drug in the first 5 hr. The effect of film coated tablet system is a capable vehicle for prevent quick hydrolysis in gastric environment and recovering oral Bioavaibility of ibuprofen for the treatment of disease of colon region.  Mihir K Raval, Riddhi V Ramani et al., 2013, studied to develop intestinal-targeted pellets of Budesonide, a potent glucocorticoid, used for the treatment of ulcerative colitis and Crohn's disease by extrusion and Spheronization method. In this study, the pellets were coated by spray coating technique using Eudragit S100 as an enteric polymer. Optimization of binders like PVP K30, pectin, guar gum, sodium alginate, and xanthan gum in 2% w/v. On the basis of physical appearance roundness, smoothness, and strength of the pellets, PVP K30 was selected as a binder for further pellet preparation.  Cheng et al. 25 developed Time-and pH-dependent colon-specific drug delivery systems (CDDS) for orally administered diclofenac sodium (DS) and 5-aminosalicylic acid (5-ASA). DS tablets and 5-ASA pellets were coated by Ethylcellulose (EC) and methacrylic acid copolymers (Eudragit® L100 and S100), respectively. Release profile of time-dependent DS coated tablets was not influenced by pH of the dissolution medium on the contrary release profile of pH dependent 5-ASA coated pellets was significantly governed by pH. It was concluded that, on using regular coating techniques also colon specific drug delivery can be obtained. Among different formulations, F14, which consists of mannitol, sucrose, HPMC, talc, magnesium carbonate, and lansoprazole, is considered to be the best formulation. Six other different formulations for the preparation of enteric coatings based on Eudragit S100, Eudragit L100, triethyl citrate, and talc were prepared and coating procedure on pellets (F14) was performed using coating pan.  D.I. Wilson et al., 2010 studied to develop an extrusion-spheronisation (E-S) route to manufacture pellets with a high loading (≥90 wt %) of 5-aminosalicylic acid (5-ASA).The influence of the API chemical and physical properties on the rheological behavior of MCC-based pastes undergoing extrusion was investigated. The performance as E-S aids of the standard Avicel PH101 grade of MCC and of colloidal ones (i.e. Avicel RC591 and CL611), alongside high loadings of 5-ASA, was also evaluated. Multi particulate E-S formulation containing not less than 90 wt%5-ASA could be developed by combining an accordingly micronized API and colloidal MCC grade.  Simone Cristina Deo et al., 2011, studied to develop and evaluate a multi particulate system consisting of pellets coated with polymer for pH-dependent release, derived from methacrylic acid and incorporated into the tablet dosage form of mesalazine as a model drug. The extrusion-spheronisation technique was used, resulting in smooth and spherical pellets with uniform size distribution, which were coated in fluidized bed using Opadry Enteric 94K28327 containing Eudragit S100 as the agent regulating drug release. The dissolution profile of coated pellets showed good control of drug release from the polymer at the two levels of coating evaluated (8% and 10%), but only the 10% coated pellets were statistically similar to Asalit 400 mg.  M. S. Shetage et al., 2014, studied Drug loaded pellets are coated with pH independent Eudragit RS100 and further coated with pH dependent Eudragit S100 in R and D pan coater. Here different concentration of Drug coating Eudragit RS100 and further coated with pH dependent Eudragit S100 in pan coater. The formulation was further characterized by in vitro dissolution study, drug release kinetics and Micromeritic properties. coating level of both the coats play a significant role in drug release property of which coating level of Eudragit RS 100 was more significant after the tablet reaches colon optimized batch having 20% w/w Eudragit RS 100 and 30% w/w with S100 as the drug release was below 20% in SIF so that it can be efficiently colon targeted, and the release is sustained up to 12 hrs which is desirable for twice daily dosing of metoprolol.  S. J. Kshirsagar et al., 2009, studied to develop the polymer coated diclofenac tablet containing superdisintegrant for colonic drug delivery and compare the in vivo performance of two polymers for site specificity. Eudragit FS 3D and Eudragit S100 were used as pH sensitive polymers. Tablets were coated separately with Eudragit FS 30D and Eudragit S100 in various thicknesses and evaluated for in vitro drug release using changing pH method In vitro release studies reveals that Eudragit FS30D coated tablet with 10%w/w coating level start release of drug at pH 6.8 after suitable lag time in the same pH which corresponds to colonic arrival time, as compare to Eudragit S100 coated tablet which release only at higher pH, approximating the transverse colon.  Sanjay K. Jain et al., 2015 studied Eudragit S100 coated Citrus Pectin Nanoparticles (E-CPNs) were prepared for the colon targeting of 5-Fluorouracil (5-FU). Citrus pectin also acts as a ligand for galectin-3 receptors that are over expressed on colorectal cancer cells. In vitro drug release studies revealed selective drug release in the colonic region in the case of E-CPNs of more than 70% after 24 h. In vitro cytoxicity assay (Sulphorhodamine B assay) was performed against HT-29 cancer cells and exhibited 1.5 fold greater cytotoxicity potential of nanoparticles compared to 5-FU solution. In vivo data clearly depicted that Eudragit S100 successfully guarded nanoparticles to reach the colonic region wherein nanoparticles were taken up and showed drug release for an extended period of time.  Minjie sun et al., 2014, studied Preparation and evaluation of colon adhesive pellets of 5aminosalicylic acid (5-ASA) for the treatment of ulcerative colitis. The core of the pellet was formulated from bioadhesive agents, Carbomer 940 and Hydroxypropyl cellulose (HPC), by Extrusion/Spheronization method and coated with Sureleaseas inner layer for waterproof and with Eudragit1 S100 as outer layer for pH control. Microcrystalline cellulose 101(PH 301) was found to be the best agent for pellet core. The ratio of CP940 to HPC should be kept as (1:1) to achieve high bioadhesion. When the amount of Surelease was from 16% to 20% and of Eudragit1 S100 was 28%, the dissolution profiles of coated pellets revealed no drug release in the artificial gastric fluid (pH 1.0) within 2 h and less than 10% was released in phosphate buffer (pH 6.0) within 2 h whereas complete dissolution was observed in colonic fluid of pH 7.4 for 20 hrs.  Raveendra M et al., 2012 studied to prepare floating microspheres of Timolol maleate using Eudragit S 100 and Eudragit L 100 as polymer. Timolol maleate is non-steroidal anti-inflammatory drug with short elimination half-life 1-3 hours. Floating microspheres of Timolol maleate were set by emulsion solvent diffusion method using Eudragit S 100 and Eudragit L 100 as polymer. Formulation EU2 prepared with Eudragit S 100 drug polymer ratio incorporation efficiency and percentage drug release 92.26 % for a period of 12 hrs.  Sharma Madhu et al., 2012, studied the formulation of Mesalazine tablet with mixture of Eudragit S-100 and L-100 as enteric coating. The core tablets of Mesalazine were ready for using wet granulation containing a superdisintegrant. The plan of here study is to develop colonic drug delivery of Mesalazine for ulcerative colitis using HPMC K-4M & HPMC K-15M as a polymer. Results also establish that mixture of Eudragit S-100 and L-100 can be effectively used to coat tablets for colon targeted release of drug.  Vivek ranjansinhaet al., 2011, studied to found the effectiveness of a mixed film composed of ethyl cellulose/Eudragit S100 for colonic delivery of 5-flourouracil (5-FU). Tablets cores containing 5-FU were prepared by direct compression method by coating at different levels with a non-aqueous solution containing ethyl cellulose/Eudragit S100. The release was establish to be higher in tablets containing Avicel as filler owing to its wicking action compare to that from lactose containing cores  Anuj Chawlaet al., 2015, studied the plan of the study was to get ready site specific drug delivery of naproxen sodium using sodium alginate and Eudragit S-100 as a mucoadhesive and pH-sensitive polymer, respectively. Core microspheres of alginate were prepared by a modified emulsification method followed by cross-linking with CaCl2, which was further coated with the pH dependent polymer Eudragit S-100 to stop drug release in the upper gastrointestinal tract. Furthermore, drug liberates from Eudragit S-100 coated microspheres follow the Korsmeyer-Peppas equation, representing 2 years shelf life of the formulation.  Faizan Sayeed et al., 2014, studied The polymers used to in the time dependent part of the release were HPMC and Ethyl cellulose with dissimilar ratios as the time with ethyl cellulose increases due to its insoluble nature and this is reduced by the soluble nature of HPMC which would give the coating layer some lipophilicity with which the release would be initiated for the drug release. The coating of these two polymers is done by dry coating method. The enteric coat over the time dependent polymer coat is to pass the dosage form from the stomach which gives a two hours lag time.  Akanksha Garud et al., 2013 studied to prepare, characterize and evaluate the colon-targeted microspheres of mesalamine for the treatment and management of ulcerative colitis (UC). Microspheres were prepared by the ionic-gelation emulsification method using tripolyphosphate (TPP) as cross linking agent. The microspheres were coated with Eudragit S-100 by the solvent evaporation technique to prevent drug release in the stomach. The release profile of mesalamine from Eudragitcoated chitosan micro-spheres was found to be pH dependent.  Lorena Segale et al., 2016, studied formulation and the coating compositions of biopolymeric pellets containing ranolazine were studied to improve their technological and biopharmaceutical properties. Eudragit L100 (EU L100) and Eudragit L30 D-55-coated alginate and alginatehydroxypropylcellulose (HPC) pellets were prepared byionotropic gelation using 3 concentrations of HPC (0.50%, 0.65%, and 1.00% wt/wt) and apply indifferent percentages (5%, 10%, 20%, and 30% wt/wt) of coating material. The pellets containing 0.65% of HPC and coated with 20% EU L100 represented the best formulation, able to limit the drug release in acidic environment and to control it at pH 6.8.  Dhiren Daslaniya et al., 2009, studied Mesalamine pellets were prepared by Coating drug solution on sugar sphere followed by various functional coating. The influence of rate controlling membrane made up of Eudragit RSPO and Eudragit RLPO in combination with delay release polymer coating with Eudragit L100 in different proportions on drug release kinetics was studied. Optimized formulation containing 796% drug loading on sugar sphere followed by coated with Eudragit L100 (15%) and Eudragit RSPO & RLPO (10% in ratio of 7:3) were evaluated for In-vitro release profile. Prepared Pellets can be used in the treatment of the ulcerative colitis.

Rationale for selection of sustained release dosage form: -
 Sustained release dosage forms maintain the plasma concentration of drug for longer period of time and avoid the fluctuations in plasma concentration, so that the dose related side effects can be avoided.  Duration of action can be prolonged hence dosing frequency can be reduced.

Rationale for selection of COX Inhibitor for sustained release dosage form: -
 Sustained release dosage forms maintain the plasma concentration of Bumadizone Calcium for longer period of time and avoid the fluctuations in plasma concentration, so that the dose related side effects can be avoided e.g. ulcers erosions.  We aimed to diminish the % of drug release before target area is to be less than 20% and to enhance the bumadizone release in the aimed area & total bumadizone release after 12 hrs. One of the most common side effects of NSAIDs is gastric discomfort and ulcers erosions.  This is due to their ability to inhibit COX-I (Cyclooxygenase-1) enzyme leading to prostaglandin (PGs) deficiency. PGs have protective role in the stomach as they regulate bicarbonate and mucous production. So generally decreasing drug release before target area will lead to both decreasing side special effects of the drug and shifting drug release in the target area.

Identification of Drug:
Identification of drug was carried out by Melting point, Fourier transform infra-red absorption spectroscopy (FTIR) and Differential scanning calorimetry (DSC).

Determination of Melting Point of Bumadizone Calcium
The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point, the solid and liquid phase exists in equilibrium. Melting point of drug was determined by capillary method using digital melting point apparatus (VEEGO VMP-DS). Fine powder of the drug was filled in glass capillary tube which was previously sealed at one end. This capillary tube was then inserted into the sample holder of the digital melting point apparatus and temperature at which the powder melted was recorded.

Drug-Excipients compatibility studies
It is the important prerequisite in development of any drug delivery system. Compatibility must be established between the active ingredient and other excipients to produce a stable, efficacious and safe product. Drug-excipients compatibility study was carried out for Drug (Bumadizone calcium hemihydrate), Excipients (MCC, EC, HPMC, PVP K30, PEG 600, and Magnesium Oxide), Physical mixture (Drug and excipients) and Final formulation using FTIR and DSC analysis. (Akula et al., 2015)

Fourier transformed infra-red absorption spectroscopy (FT-IR)
Drug and excipients compatibilities were analyzed by IR spectral studies. IR spectra of drug, polymer, drug-polymer physical mixture and the formulation were obtained using FTIR spectrophotometer. Fourier-transformed infrared spectra were obtained on FTIR spectrophotometer (Thermo scientific) using the KBr disk method (2mg of sample in 200 mg of KBr). 1-2 mg of sample was gently triturated with KBr powder and compress into disc by applying pressure for 10 min in a hydraulic press. The scanning range was 400 to 4000 cm-1 and the resolution was 1 cm-1. (Narang and Sharma, 2011)

Differential Scanning Calorimetry (DSC)
Drug and excipients compatibility studies of pure drug, excipients, physical mixture, and final formulation were analyzed by DSC. DSC analysis was carried out using aluminium sample pans in Differential Scanning Calorimetry (DSC-60, Shimadzu, Japan) at a heating rate 10 ºC per minute in the range 30 to 300 ºC using differential scanning calorimetry (DSC). The pellets of bumadizone were prepared by using extruder and Spheronization. All The excipients and drug (bumadizone, HPMC, EC, and MCC) were passed through sieve no.40 prior to pelletization and mixed uniformly. Then PVP K30/xanthan gum/pectin (0.5, 1.0, 1.5%w/v) solution was added in sufficient quantity and mixed it. The obtained dough mass was extruded using a piston extruder (1.5mm orifice). The extrudates were immediately spheronized in 80mm diameter friction plate with groove space of 5mm for 15min at a rotation speed of various rpm. The pellets were dried over night at room temperature.

COATING OF THE PREPARED PELLETS
Eudragit S100 as a pH dependent polymer dispersed in the acetone and isopropyl alcohol (1:1) and made the (4, 5, 6%w/v) solution for the coating then added the triethyl citrate as a plasticizer. The details of the coating procedure are summarized in the table.

Screening of Binder Concentration
Preliminary work was carried out for screening of different binder and its concentration.

Screening of Spheronization speed (rpm)
Preliminary work carried out for screening of Spheronization speed.

Effect of Polymer & Eudragit concentration on release profile
Preliminary work carried out for Effect of Ethyl Cellulose, drug to polymer ratio and Effect of concentration of Eudragit S100 on release profile.

.2 Formulation optimization using 3² Full Factorial Design
A 32-randomized full factorial design will be used to quantify the significant independent variables revealed from preliminary studies. In this design 2 factors will be evaluated, each at 3 levels, and experimental trials will be performed at all 9 possible combinations generated by Design Expert 10.0. Two independent variables namely X1 (PVP K30), and X2 (% EUDRAGIT S100). (Patel et al., 2014) On the bases of preliminary batches results, the low, medium and high values of independent variables will be selected and the batches from B1 to B9 will be formulated. The critical parameter of the Liquid-solid compact formation will be selected as responses. They will be as follows.

Equation relating independent variables and responses
The equations relating independent variables and responses will be obtained by subjecting the results to statistical evaluation. Microsoft Excel version 2010 will be used to perform multiple linear regressions to determine the control factors that significantly affect the responses. The details of which is given below:

Polynomial equation for 32 full factorial design (Patel et al., 2014)
Y = β0 + β1X1 + β2X2 +β12X1X2 + β11X12 +β22X22 + E Where, Y is the measured response, β0 is the constant, β1, β2 are the coefficient for the factor X1, X2, β12, is the coefficient of interaction, β11, β22, are the coefficients of the quadratic terms, E is the error term The main effects (X1 and X2) represent the average result of changing one factor at a time from its low to high value. The interaction terms (X1 and X2) show how the response changes when 2 factors are simultaneously changed. The polynomial terms (X11 and X22) are included to investigate nonlinearity. The significant factors in the equations will be selected using a stepwise forward and backward elimination for the calculation of regression analysis. The terms of full model having non-significant p value (p > 0.05) have negligible contribution in obtaining dependent variables and thus are neglected. A 32-factorial design will have been applied to optimize enteric coated Bumadizone calcium pellets formulation.
The positive sign of coefficient for factors that indicate synergistic effect on the response while negative sign of coefficient for factors that indicate antagonistic effect on response variable. The relationship between the dependent and independent variables will further elucidate using response surface plots. The equation enables the study of the effects of each factor and their interactions over the considered responses. Acetone 50ml 50ml 50ml 50ml 50ml 50ml 50ml 50ml 50ml IPA 50ml 50ml 50ml 50ml 50ml 50ml 50ml 50ml 50ml

Counter Plots and Surface Response Plots 5.4.3.1 Counter plots (Patel et al., 2014)
Contour plots are diagrammatic representation of the values of the response. They are helpful in the explaining relationship between independent and dependent variables. The two-dimension contour plots will be prepared using statistic software. (Design Expert 10.0)

Surface response plots (Patel et al., 2014)
Response surface plots are more helpful in understanding both the main and the interaction effect of variables. The effect of different levels of independent variables on the response parameters can also be predicted from the respective response surface plots. For check point batch analysis Overlay plot will be prepared by using statistic software (Design Expert 10.0).

Evaluation Parameters 5.5.1 Drug Content Uniformity
Bumadizone content of the pellets were evaluated using accurately weighed 100mg pellets, after completely powdering pellets in a mortar. The completely powder was dissolve into methanol and made the volume up to 100 ml using phosphate buffer pH 7.4 and scanned between 200-400 nm using shimadzu 1800 U.V. spectrophotometer.

In-vitro Dissolution Study:
The release rate of bumadizone from pellets was determined using USP dissolution testing apparatus I (basket type). The test was performed using 900ml of simulated gastric fluid (pH 1.2) at 37±0.5°C and 50 rpm for first 2 hrs then dissolution medium replaced with 6.8 phosphate buffer for 2 hrs and finally it was 7.4 phosphate buffer for 8 hrs. (Dissolution study extended upto 8 hrs due to for colon target drug delivery).

Bulk Density (BD):
It is the ratio of powder to bulk volume. The bulk density depends on particle size distribution, shape and cohesiveness of particles. Accurately weighed quantity of powder was carefully poured into graduated measuring cylinder through large funnel and volume was measured which is called initial bulk volume. Bulk density is expressed in gm/ml and is given by Bulk Density = Weigh of powder/Bulk volume

Tapped Density (TD):
Ten grams of powder was introduced into a clean, dry 100ml measuring cylinder. The cylinder was then tapped 100 times from a constant height and tapped volume was read. It is expressed in gm/ml and is given by Tap Density = Weigh of powder/Tap volume

Hausner's Ratio (HR):
The Hausner's s ratio of the powder was determine by the following formula Hausner's Ratio= TD/BD

Angle of Repose (θ):
It is defined as the maximum angle possible between the surface of pile of the powder and the horizontal plane. Fixed funnel method was used. A funnel was fixed with its tip at a given height (h), above a flat horizontal surface on which a graph paper was placed. Powder was carefully poured through a funnel till the apex of the conical pile just touches the tip of funnel. The angle of repose was then calculated using the formula, Θ = Tan-1 (height of pile/radius of pile)  Table 5.12 Relationship between powder flow and Hausner's ratio

Friability:
Friability is interconnected to the capability of pellets to survive both shocks and abrasion lacking crumbling through manufacturing, packing, transportation & consumer handling. Friability can be calculated by means of friability test apparatus Roche friabilator. Compressed pellets that range are less than 0.5% to 1.0% in weight. Method: -Ten pellets were weighed (initial weight) and then transfer into Roche friabilator (Abrasion Drum). It was subjected to 100 revolutions in 4 min. The pellets were de-dusted and reweighed (final weight). These two weights were applied to following formula and friability was calculated. % Friability = (Initial weight -Final weight) / (Initial weight) × 100
In accelerated stability testing, the coated pellets to be stored under controlled conditions of 40°C/75% RH over a period of 1 month. The coated pellets were filled in capsules and packed in blister pack. Then kept in stability chamber at 40°C/75% RH over a period of 1 month. The pellets were evaluated for drug content, flow properties and other parameters at the end of 30 days.

. Spectrum of Bumadizone calcium in for determination of λmax by UV visible spectrophotometer.
A different concentration of Bumadizone calcium solution was prepared in pH 6.8, 7.4, 1.2 and methanol was scanned in UV range between 200 to 400nm wavelength (λmax) for the analysis. (Narang and Sharma, 2011) Bumadizone calcium showed maximum absorbance at 236nm.   Concentration of 4,6,8,10,12,14,16, and 18 μg/ml were prepared and scanned in UV spectrophotometer. Bumadizone showed maximum absorbance at 236 nm. Thus, 236 nm was selected as λmax for Bumadizone Calcium.     DSC enables the Quantitative detection of all processes in which energy is required or produced (i.e., endothermic or exothermic phase transformation). The thermal behaviour of the prepared samples was studied by DSC at the rate of 10°C/min rise in temperature up to 350°C. The DSC thermograms of pure drug and physical mixture are shown in figure 21.  DSC enables the Quantitative detection of all processes in which energy is required or produced (i.e., endothermic or exothermic phase transformation). The thermal behavior of the prepared samples was studied by DSC at the rate of 10°C/min rise in temperature up to 350°C. The DSC thermograms of pure drug and physical mixture are shown in figure.

Figure 23: DSC of physical mixture
The DSC thermogram of Bumadizone and physical mixture shown in figure. DSC thermograph of Bumadizone Calcium exhibits endothermic peak at 154.34°C corresponding to its melting point. Mixture of excipients and Bumadizone Calcium shows endothermic peak at 153.26°C which indicates almost no interaction.

Fourier Transform Infra-Red Spectroscopy (FT-IR)
The FTIR spectrum of Physical mixture and Formulation (uncoated & coated pellets were shown in figure 23, 24 and 25 respectively. In the FT-IR spectrum of Physical mixture and Formulation characteristic peaks corresponding to their functional groups were identified, which were same in Bumadizone Calcium pure drug. Thus, there was no any interaction between drug and excipients.

Result of preliminary trial for selection of diluent concentration
During screening of diluent concentration batches F1-F3 were prepared and they were evaluated with respect to size, shape, and strength.

Result of preliminary trial for selection of Binder
During screening of binder concentration batches F4-F12 were prepared and they were evaluated with respect to size, shape, and strength.

Result of preliminary trial for selection of plasticizer
During screening of plasticizer batches F13-F15 were prepared and they were evaluated with respect to size, shape, and strength. From the result table, It was found that PEG 600(1ml) shows uniform size, spherical shape and good strength. Hence it was selected for further study.

Result of preliminary trial for selection of polymer
During screening of polymer batches F16-F24 were prepared and they were evaluated with respect to size, shape, and strength.

Result of preliminary trial for selection of Spheronization speed
During screening for selection of speed batches F25-F27 were prepared and they were evaluated with respect to size, shape, and strength.     22 Different flow parameters of prepared pellets suggested that all the pellets showed excellent flow property range show it indicated that prepared pellets have excellent flow property. The friability of the pellets was found to be in the range 0.22-0.35%, which indicated good mechanical strength of pellets. Percentages of drug content in prepared enteric coated pellets were found to be in the range of 96.18 to 98.22 which is within the acceptable limit.  The 3 2 -full factorial design was used to optimize the amount of binder and coating material in formulation of Enteric coated pellets. The amount of binder and coating material is selected on the basis of in-vitro dissolution study.
3 2 full factorial design was used and prepared total 9 batches (F1 to F9). In those two independent factors % of Binder (X1), and Concentration of Eudragit S100(X2) were used and two factors had three levels low, medium, and high (-1, 0 and +1) which are given in table 5. 16. The dependent factors were selected like % CPR at 12 hrs (% Cumulative drug release), CPR at 2hrs, and CPE (coating process efficiency) based on the selected dependent variable for optimization of formulation. Eudragit S100(X 2 ) 4% 5% 6% All possible 9 runs of formulation having a different coded value for optimization of Enteric coated pellets for maximum % drug release at maximum time and minimum release in stomach.    The analysis of contour plot and surface plot of % CPR (Y) against conc. of PVP K30 (%w/v) (X1), and conc. of Eudragit S100 (%w/v) (X2) were shown in figure 5.28, and 5.29. From the figure it could be concluded that % CPR after 2hrs was affected by selected Independent variables. Conc. of PVP K30 (%w/v) (X1) was increase then % CPR after (Y1) was decreased. Conc. of Eudragit S100 (%w/v) (X2) increased the % CPR after 2hr (Y1) also decreases. From the figure (X1) and (X2) are significant for the % CPR after 2hrs (Y1).  The analysis of contour plot and surface plot of % CPR after 12hrs (Y2) against conc. of PVP K30 (%w/v) (X1), and conc. of Eudragit S100 (%w/v) (X2) were shown in figure 5.30, and 5.31. From the figure it could be concluded that that % CPR after 12hrs was affected by selected Independent variables. Conc. of PVP K30 (%w/v) (X1) was increase then % CPR after 12hrs (Y2) was decreased. conc. of Eudragit S100(%w/v) (X2) increased the % CPR after 12hr (Y2) also decreases. From the figure (X1) and (X2) are significant for the % CPR after 12hrs (Y2).  The analysis of contour plot and surface plot of % CPE (Y3) against conc. of PVP K30 (%w/v) (X1), and conc. of Eudragit S100 (%w/v) (X2) were shown in figure 5.30, and 5.31. From the figure it could be concluded that that % CPE was affected by selected Independent variables. Conc. of PVP K30 (%w/v) (X1) was increase then % CPE (Y3) was decreased. Conc. of Eudragit S100 (%w/v) (X2) increased the % CPE(Y3) also decreases. From the figure (X1) and (X2) are significant for the% CPE (Y3).
Overlay plots of three responses could be used to determine desired concentration of PVP K30 and Eudragit S100. In above figure, yellow region of overlay plot showed desired range of responses. By choosing any concentration of PVP K30 and Eudragit S100 in this region, desired responses could be achieved.

Check point batch analysis
From the overlay plot, check point was selected in order to obtain desired value of factors. On the basis of desired criteria of drug release % after 2hrs, % drug release after 12hrs and coating process efficiency, following batch was formulated to assess the reliability of the evolved equations. The experimental values and predicted values of each response are shown in table.
The percentage relative error of each response was calculated using the following equation: % relative error = [(predicted value-Experimental value)]/ predicted value] ×100   The % relative error for the checkpoint batch was in the range of 0. 26-2.13. This is less than 8%, so statistically acceptable. It was concluded that the experimental values and predicted values showed good agreement between each other.

Evaluation Parameters 6.4.1 Evaluation of pellets by size, shape & strength
All Pellets are uniform size, spherical shape and with good strength. Core (uncoated) pellets are 1.4 to 1.6 mm of diameter range. Coated Pellets are ranged from 1.8 to 2.2mm of diameter range.

Evaluation of pellets by its flow property & drug content
Enteric Coated pellets blend was characterized for micrometrics properties like, Angle of repose, Bulk density, Tapped density, Carr's index and hausner's ratio. Different flow parameters of prepared pellets suggested that all the pellets showed excellent flow property range show it indicated that prepared pellets have excellent flow property. The friability of the pellets was found to be in the range 0.20-0.35%, which indicated good mechanical strength of pellets (Gowda D et al., 2012). Percentage of drug content in prepared enteric coated pellets were found to be in the range of 95.85 ± 0.80 to 98.64 ± 0.37, which is within the acceptable limit.

Stability Study
The samples of optimized batch (B3) were kept in accelerated condition (40˚±2˚C/75% ± 5% RH) for one month. Then samples were analyzed for physical evaluation, assay and dissolution. The results are given in Table. After 1 month of accelerated stability, the pellets were uniform size, spherical shape and good strength. They also maintained excellent flow property. The drug content of optimized batch before and after accelerated stability study had no major change. The comparative release profile of optimized batch before and after stability study results no significant change in release pattern.

CONCLUSION
The objective of the study was to prepare and evaluate bumadizone calcium colon targeted pellets by extrusion and spheronization followed by coating for sustained release. By using Eudragit S100 (pH resistant polymer), HPMC K15 M, Ethyl Cellulose and PVP K30, it can successfully to obtain desired drug release and gastric retention. 3 2 full factorial designs applied and got desirable optimized batch which show the sustained release of the drug up to longer duration of time. The method applied was simple, rapid and economical and did not imply the use of toxic solvents. Based on result, 5% coating level formulations are suitable for the successful delivery of the drug into the lower part of intestine and colon. By preparing sustained release pellets of Bumadizone calcium, bioavailability of Bumadizone calcium can be achieved. Summary of the above results were listed below. The results of micromeritic properties of pellets show excellent flow property.  From the FTIR and DSC studies, it was observed that there is no chemical interaction between drug and excipients used in the formulations.  Drug loaded pellets exhibited spherical shape with uniform and smooth coating.  The Drug content and Friability of pellets is uniform and found satisfactory.  Optimized batch shown that less than 0.50% of the drug released at the end of 2hrs in pH 1.2, less than 20% of drug released after end of four hrs in pH 6.8 and more than 85% at the end of 12hrs in pH 7.4.  Accelerated stability study data for 1 month was found satisfactory. From the above results of the research work, we can conclude that colon targeted enteric coated pellets of bumadizone calcium has been successfully prepared and can be used for sustained delivery in the treatment of Inflammatory Bowel Disease.