Formulation and In-Vitro Evaluation of Mucoadhesive Floating Microspheres of Repaglinide Using Solvent Evaporation Method

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1 ISSN Available online at Research Article Formulation and In-Vitro Evaluation of Mucoadhesive Floating Microspheres of Repaglinide Using Solvent Evaporation Method K. Harinada Baba, A. Purna Chandra Rao Ch. Geetha Anoosri, B. Priya Darshini and R. Vara Lakshmi Faculty of Pharmaceutical sciences, Rajiv Gandhi College of Pharmacy, Rajahmundry, East Godavari, Andhra Pradesh, India. ABSTRACT The purpose of this study is to Formulation and In-vitro Evaluation of Muco-adhesive Floating Microspheres of Repaglinide using solvent evaporation method. The floating microspheres were taken for micromeritic properties such as bulk density, tapped density, Carr s index, hausners ratio, angle of repose. SEM studies shown that microspheres had to 5 µm. the dissolution data it was evident that, formulations prepared with Eudragit S were revealed that formulations may not contain even 9% of drug. Hence those formulations were not considered. Formulations prepared with Ethyl cellulose was shown those contain more than 9% of drug. F5 formulation was the maximum drug release up to 12 hrs. Hence It was considered as optimized formulation. The optimized formulation was kept for drug release kinetics. It was followed Kars Mayer, peppas release kinetics. Optimized formulation was taken for muco-adhesion strength. Peak detachment force (N) was found to be 4.5 and work of adhesion was mj. Keywords: Repaglinide, Ethyl cellulose, Eudragit S, Floating microspheres. INTRODUCTION The oral route of drug administration is the most important method of administering drugs for systemic effects. The parenteral route is not routinely used or not possible to selfadministration of medication. The topical route of administration has only recently been employed to deliver drugs to the body for systemic effects. It is probable that at least 9 % of all drugs used to produce systemic effects are administered by the oral route. When a new drug is discovered, one of the first questions a pharmaceutical company asks is whether or not the drug can be effectively administered for its intended effect by the oral route. If it cannot, the drug is primarily relegated to administration in a hospital setting or physician's office. Of drugs that are administered orally, solid oral dosage forms represent the preferred class of product. The reasons for this preference are well known. Novel Drug Delivery System Today, a pharmaceutical scientist is well versed with the fact that the overall action of a drug molecule is not merely dependent on its inherent therapeutic activity, rather on the efficiency of its delivery at the site of action. An increasing appreciation of the latter has led to the evolution and development of several drug delivery systems (DDS) aimed at performance enhancement of the potential drug molecules. NDDS with improved bioavailability (BA). To formulate a drug or to re-formulate it in a form of NDDS is not a Herculean task if one goes methodically and skill-fully. This is where the formulation development studies play an important role. Pharmaceutical aspects of gastro retentive drug delivery system (GRDDS) In designing GRDDS, the following characteristics should be sought: convenient intake, retention in the stomach according to clinical demand; ability to load substantial amount of drugs with different physicochemical properties and release them in controlled manner; complete degradation, preferable in the stomach.gastric retention will provide advantages such as the delivery of drug with narrow absorption window in the small intestinal region. Also longer residence time in the stomach could be advantages for local action in the upper part of small intestine; e. g. in the treatment of peptic ulcer disease, further more improved bioavailability is expected for drug that absorbed readily upon release in the GI tract. To achieve gastric retention, the dosage form must satisfy certain requirements one of the key issue is that the dosage form

2 ISSN Available online at must be able to withstand the force caused by peristaltic waves in the stomach and the constant contraction, grinding and churning mechanism. Gastro retentive technologies (GRT) A number of systems have been used to increase the GRT of dosage forms by employing a variety of concepts. These systems have been classified according to the basic principles of gastric retention. Floating Drug Delivery System (FDDS) Floating dosage form is also known as hydro dynamically balanced system (HBS). FDDS have a bulk density less than gastric fluids and so remain buoyant in the stomach without affecting the gastric emptying rate for a prolonged period of time while the system is floating on the gastric contents, the drug is released slowly at the desired rate. After release of drug, the residual system is emptied from the stomach. It is formulation of a drug (capsule or tablet) and gel forming hydrocolloids meant to remain buoyant on stomach contents. This not only prolongs GI residence time but also does so in an area of the GI tract that would maximize drug reaching its absorption site in solution and hence ready for absorption. Drug dissolution and release from the capsule retained in stomach fluids occur at the stomach, under fairly controlled condition. The retentive characteristics of the dosage form in gastric content are most significant for drugs which are insoluble in intestinal fluid, that acts locally and that exhibits site specific absorption. Advantages of floating drug delivery system An FDDS offers numerous advantages over conventional DDS 1. The gastro retentive systems are advantageous for drugs absorbed through the stomach. E.g. Ferrous salts, antacids. 2. Acidic substances like aspirin cause irritation on the stomach wall when come in contact with it. Hence HBS formulation may be useful for the administration of aspirin and other similar drugs. 3. Administration of prolongs release floating dosage forms, tablet or capsules, will result in dissolution of the drug in the gastric fluid. They H 2 O Drug dissolve in the gastric fluid would be available for absorption in the small intestine after emptying of the stomach contents. It is therefore expected that a drug will be fully absorbed from floating dosage forms if it remains in the solution form even at the alkaline ph of the intestine. 4. The gastro retentive systems are advantageous for drugs meant for local action in the stomach. e.g. antacids. 5. When there is a vigorous intestinal movement and a short transit time almighty occur in certain type of diarrhea, poor absorption is expected. Under such circumstances it may be advantageous to keep the drug in floating condition in stomach to get a relatively better response. Need for the study Oral drug delivery is the most desirable and preferred method of administering therapeutic agent for their systematic effect such as patient acceptance, convenience in administration and cost effective manufacturing process. Thus wide variety of approaches of drug delivery system has been investigated for oral application. However development process is precluded by several physiological difficulties, such as inability to restrain & localize drug delivery system within desired region of GIT tract and highly variable nature of gastric emptying process. For example relatively brief gastric emptying time can result in incomplete drug release from drug delivery devices leading to diminished efficacy of administered dose. Floating drug delivery system is noted orally applicable drug delivery system for prolongation of gastric emptying time. The bulk density of floating drug delivery system is lower than that of gastric fluid and thus it remains buoyant on stomach content for long time in the drug releasing process. Hence it is useful for obtaining sufficient bioavailability for long time and effective plasma level. Microspheres provide a constant & prolonged therapeutic effect which will reduce dosing frequency. It was reported that microspheres prepared with proton pump inhibitor effective in reducing gastric acid level and allowing acid related disease to heal. MATERIALS AND METHODS Repaglinide, Ethyl Cellulose, Eudragit S, Ethanol, Dichloromethane, Tween, Hydrochloric acid, Sodium bicarbonate. Preparation of calibration curve in.1n HCl 1mg of Repaglinide pure drug was dissolved in 1ml of methanol (stock solution 1). 1ml of solution was taken and made up with 1ml of

3 ISSN Available online at N HCl (μg/ml) stock-2. From this 1ml was taken and make up with 1 ml of.1n HCl (1μg/ml) stock-3. The above stock-ii solution was subsequently diluted with.1n HCl to obtain series of dilutions containing and 1,, 3, and 5μg/ml of solution. The absorbance of the above dilutions was measured at respective wavelength by using UV-Spectrophotometer taking.1n HCl as blank. Then a graph was plotted by taking Concentration on X-Axis and Absorbance on Y-Axis which gives a straight line Linearity of standard curve was assessed from the square of correlation coefficient (R 2 )which determined by least-square linear regression analysis. Drug and Excipient Compatibility studies The compatibility between the pure drug and excipients was detected by FTIR spectra obtained on Bruker FTIR Germany(Alpha T).The solid powder sample directly place on yellow crystal which was made up of ZnSe. The spectra were recorded over the wave number of to cm -1. Trial and Error for determining the floating microspheres In trial and error method, microspheres were prepared with polymer only whether to know obtaining microspheres. In another formulations different concentrations of sodium bi carbonate was added to polymer and prepared microspheres. Then compared buoyancy between those formulations which contains only polymer and another contains polymer along with sodium bicarbonate. By trial and Error method, It concluded that microsphere along with sodium bicarbonate was showing good buoyancy and sodium bicarbonate concentration was also optimised. Trial and Error formulations Formulation Code Ethyl cellulose(mg) Sodium bicarbonate(mg) T1 - T2 5 T3 T4 15 T5 Preparation of Floating microspheres The floating microspheres were prepared by solvent evaporation method. Drug and Required polymer, Excipients were taken in different ratios as shown in table 1. Drug and excipients were dissolved in ethanol and dichloromethane (1:1). The obtaining Drug and polymer solution was poured slowly using syringe into ml of water containing 5% V/V Tween. Preparation was stirred at 3 rpm for 1 hour. The obtained floating microspheres were filtered and dried overnight at room temperature. Formulation code Table 1: Formulation of floating Microspheres Ethyl Eudragit Sodium cellulose S Bicarbonate (mg) (mg) (mg) Drug (mg) DCM (ml) Ethanol (ml) F F F F F F F F F F RESULTS AND DISCUSSION Pre-formulation studies Spectrum curve of Repaglinide

4 ISSN Available online at Concentration (µg/ml) Absorbance Drug- Excipient Compatibility studies FTIR of Repaglinide pure drug FTIR spectrum of Ethylcellulose DSC (DIFFERENTIAL SCANNING CALORIMETRY) STUDIES REPAGLINIDE DSC Spectrums REPAGLINIDE + Ethyl cellulose DSC Spectrum SEM studies

5 F1 F2 F3 F4 F5 F6 F7 F8 F9 F1 % BUOYANCY % EFFICIENCY PARTICLE SIZE % YIELD ISSN Available online at Characterization of microspheres Micrometric Properties Formulation code Mean particle size Bulk density (gm. /cm 3 ) Tapped density (gm. /cm 3 ) Hauseners ratio Carrr s index Angle of repose F ±1.8.36±.4.44± ± ±.3 27.±1.93 F ±2.7.41±.5.47± ± ± ±1. F ±2.43.±.1.48±.2 1.2± ± ±1.43 F ± ±.2.± ± ± ±1.89 F ±2.5.±.7.47± ± ± ±2.78 F ± ±.1.5± ±.2 12± ±1.68 F ± ±.6.39± ± ± ±1.71 F ± ±.1.45± ± ±.4 26.±1.68 F ± ±.5.48± ± ± ±1.59 F1 1.51± ±.7.44± ± ± ±1.8 All values represented as mean ± standard deviation (n=3) Percentage yield, in-vitro buoyancy and incorporation efficiency of floating microspheres of Repaglinide Formulation code Percentage yield In vitro buoyancy Entrapment (%) Efficiency (%) F ± ± ±1.72 F ± ± ±1.94 F ± ± ±2.1 F4 93.8± ± ±2.47 F ± ± ±2.7 F6 84.5± ± ±1.46 F ± ± ±1.67 F ± ± ±2.5 F ± ± ±1.85 F ± ± ±1.15 All values represented as mean ± standard deviation (n=3) F1 F2 F3 F4 F5 F6 F7 F8 F9 F1 FORMULATION CODE F1 F2 F3 F4 F5 F6 F7 F8 F9 F1 FORMULATION CODE Comparison of average particle size of floating microspheres of Repaglinide F1 F2 F3 F4 F5 F6 F7 F8 F9 F1 FORMULATION CODE FORMULATION CODE Comparison of yield of floating microspheres of Repaglinide

6 TIM E (hr) ISSN Available online at comparison of percent in-vitro buoyancy of floating microspheres of Repaglinide 2. Comparison of drug entrapment efficiency of floating microspheres of Repaglinide In Vitro drug release In-Vitro drug release data of Repaglinide microspheres F1 to F5 Tim % cumulative drug release e (hrs) F1 F2 F3 F4 F ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 1.24 Cumulative % Drug Release F6 F7 F8 F9 F ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±.91.55± ± ± ± ± ±.62.8± ± ±.15 Ex-vivo mucoadhesion study Formulation Code After 1 hr After 2 hr After 3hr After 4 hr F The Mucoadhesive property of the optimized formulation of microspheres was evaluated by in vitro adhesion testing methods called in-vitro wash off test / Ex-vivo mucoadhesion study. The numbers of microspheres adhering to the tissue were calculated after 3 min, 1 hr and hourly at 4 hr. After determination it was found that optimized formulation showed more than 75% mucoadhesion.

7 Log Cumulative % drug release Log % drug remaining Cumulative % drug relase Cumulative % drug release ISSN Available online at Drug Release Kinetics CUMULATIVE (%) TIME LOG( %) ROOT (T) RELEASE Q (T) RELEASE LOG (T) LOG (%) REMAIN Zero y = 8.952x -.66 R² = time 1 15 Graph of Zero order release kinetics Higuchi y = 3.33x R² = Root Time Graph of Higuchi release kinetics Peppas y = x R² = Log Time First y = -.912x R² = time Graph of Peppas release kineticsgraph of First order release kinetics From the release kinetics data, It was evident that optimized formula was followed Zero order release kinetics. The percentage yield of floating microsphere formulation F1 to F1 was in range of 84.5±.39to 97.48±.57. The purpose of preparing floating microspheres was to extend the gastric residence time of a drug. The in vitro buoyancy of formulation F1 to F1, it was range from 7.42±1.36 to 95.81±2.11 respectively. The entrapment efficiency of formulation F1 to F1 was in the range of 81.62±1.72to 95.62±2.7. From the dissolution data it was evident that, formulations prepared with Eudragit S were revealed that formulations may not contain even 9% of drug. Hence those formulations were not considered. Formulations prepared with Ethyl cellulose was shown those contain more than 9% of drug. F5 formulation was the maximum drug release up to 12 hrs. Hence It was considered as optimized formulation. Optimized formulation was kept for drug release kinetics. It was followed Kars Mayer peppas release kinetics. Optimized formulation was taken for mucoadhesion strength. Peak

8 ISSN Available online at detachment force (N) was found to be 4.5 and work of adhesion was mj. REFERENCES 1. Banker GS, Anderson NR. Tablets: The theory and practice of industrial pharmacy.3rd. Bombay: Varghese Pub. House; Chein YW. Novel Drug Delivery Systems. 2nd Ed. New York: Marcel Dekker. Inc Lee TW, Robinson JR. Remington: The Science and Practice of Pharmacy. th Ed. Pennsylvania: Mack Publishing Company; Aulton ME. Pharmaceutics: The Science of Dosage Form Design. 2nd ed. Livingstone C. Elsevier science Ltd; Welling PG, Dobrinska Controlled drug delivery: Fundamentals and applications. 2nd Ed. New York: Marcell Dekker Inc.; Brahmankar DM, Jaiswal SB. Bio pharmaceutics and Pharmacokinetics a treatise. Reprint of 1st Edn. Delhi: Vallabh Prakashan; 3.