IN-VITRO AND EX-VIVO EVALUATION OF MUCOADHESIVE TABLETS USING NATURAL POLYMERS BY GASTRO RETENTIVE DRUG DELIVERY SYSTEM

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1 Page445 Indo American Journal of Pharmaceutical Research, 2013 ISSN NO: Journal home page: INDO AMERICAN JOURNAL OF PHARMACEUTICAL RESEARCH IN-VITRO AND EX-VIVO EVALUATION OF MUCOADHESIVE TABLETS USING NATURAL POLYMERS BY GASTRO RETENTIVE DRUG DELIVERY SYSTEM D.Krishnarajan *1, 2, N.Senthil Kumar 1, 2, Sasikanth Kanikanti 1 1 Department of pharmacy, JKK Munirajah Medical Research Foundation College of Pharmacy, Ethirmedu, B.Komarapalaym, Namakkal , Tamilnadu, India. 2 Department of pharmacy, Sunrise University, Alwar, Rajasthan , India. ARTICLE INFO Article history Received 09/11/2013 Available online 31/01/2014 Keywords Gastro retentive delivery, Natural polymer, Mucoadhesive, swelling index. ABSTRACT The aim of the present study was to determine the comparative mucoadhesive strength, mucoadhesive force and mucoadhesive retention time of some natural polymerts by simple invitro method. Various natural polymers were selected in the current study. The tablets were prepared by wet granulation method and the following evaluation methods were used such as swelling index, mucoadhesive strength, mucoadhesive force, ex-vivo mucoadhesive time and in-vitro mucoadhesive retention time was determined. And all these in-vitro evaluations were done by using goat intestinal mucous memberane. The study reveals that the ascending order of natural polymers for formulating a gastro retentive mucoadhesive system was found to be gum Arabic(1.53) < neem gum(1.55) < locust bean gum(1.60) < tragacanth(1.64) < chitosan(1.71) < guar gum(1.82) < xanthan gum(1.87) < karaya gum(1.92) < carbopal 934(2.27). Corresponding author D.Krishnarajan Department of pharmacy, JKK Munirajah Medical Research Foundation College of Pharmacy, Ethirmedu, B.Komarapalaym, Namakkal , Tamilnadu, India. Please cite this article in press as D.Krishnarajan et al. In-vitro and ex-vivo evaluation of mucoadhesive tablets using natural polymers by gastro retentive drug delivery system. Indo American Journal of Pharm Research.2014:4(01). Copy right 2013 This is an Open Access article distributed under the terms of the Indo American journal of Pharmaceutical Research, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

2 Page446 INTRODUCTION: Dosage form is retained in stomach are called gastro retentive drug delivery systems (GRDDS). GRDDS is improved controlled delivery of drugs and absorption window by continuously releasing the drug for a prolonged period of time before it reaches its absorption site, thus ensuring its optimal bioavailability. Drugs having narrow absorption window are mostly associated with improved absorption at jejunum and ileum due to enhanced absorption properties e.g. large surface area, or enhanced solubility in stomach as opposed to the more distal parts of the GIT. Mucoadhesion is the state in which two materials, at least one biological in nature, are held together for an extended period of time by interfacial forces. It is also defined as the ability of a material (synthetic or biological) to adhere to a biological tissue for an extended period of time.for drug delivery purpose, the term bioadhesion implies attachment of a drug carrier system to a specific biological location. The biological surface can be epithelial tissue. If adhesive attachment is to a mucus coat, the phenomenon is referred to as mucoadhesion. Bioadhesion can be modeled after a bacterial attachment to tissue surfaces, and mucoadhesion can be modeled after the adherence of mucus on epithelial tissue. Mucus is a thin blanket covering all epithelia that are in contact with the external environment in the gastrointestinal, respiratory and urogenital tracts. In each case of these mucosal routes, mucus characteristics and functions are different. [1, 2] Drug delivery via the membranes of the oral cavity can be subdivided as Sub lingual delivery, buccal delivery and local delivery. These oral mucosal sites be at variance greatly from one another, on terms of anatomy, Permeability, to an applied drug, and their ability to maintain a drug delivery system for desired length of time. Because of easily accessibility it permits localization of the system. Since the patients are well modified to oral administration of drugs in general, patient recognition and compliance is expected to be good. Its ability to convalesce after local treatment is evident and hence allows a wide range of formulations to be used e.g. bioadhesive patches and ointments. [3, 4] The main idea of mucoadhesive was derived from the need to localize drugs at a certain site in the body. Often the extent of drug absorption is limited by the residence time of the drug at the absorption site. For e.g. in ocular drug delivery system, less than 2 min. are available for drug absorption after instillation of a drug solution into the eye, since it is removed rapidly by the solution drainage and hence the ability to extend the contact time of an ocular delivery system in front of the eye would undoubtedly improve the bioavailability. In oral drug delivery, the drug absorption is limited by the GI transit time of the dosage form. Since many drugs are absorbed only from the upper small intestine, localizing oral drug delivery system in the stomach or in the duodenum would significantly improve the drug absorption. To overcome the relatively short GI retention time and improve localization for oral controlled drug delivery system, bioadhesive polymers which adhere to the mucin or the epithelial surface are effective and lead to significant improvement in oral drug delivery. MATERIALS AND METHODS: Guar gum, xanthan gum, karaya gum, Carbopal 934, chitosan, gum Arabic, neeem gum, tragacanth and locust bean gum were purchased from Yarrow Chem Products, Mumbai and all remaining excipients are purchased from Scientific Lab, Erode. And for determination of mucoadhesive strength and for other evaluations goat intestinal mucous membarane was obtained from local butcher shop. PREPARATION OF MUCOADHEISVE TABLETS: Mucoadhesive tablets of different polymers were prepared by wet granulation method. In all the formulations the amount of polymer used is 75mg except in the blank tablet only lactose of 175mg was used. All the ingredients were blended to form a uniform mixture in a glass mortar for 15 min and then polyvinyl pyrrolidone was added as a binding agent up to the formation of mass. These mass was passed through the 8mm screen mess to form the granules. Then the formulated granules were dried in hot air oven at 60 C for 30mints. Magnesium stearate (MS) was added as a lubricant in the granules and mixed. The blended granules were then compressed 8mm length die concave punches on tablet compression machine. Table1: Composition of mucoadhesive tablets Batchs INGREDIENTS QUANTITY LACTOSE MAGNESIUM STEARATE TOTAL(mg) F F2 Guar gum F3 Xanthan gum F4 Karaya gum F5 Chitosan F6 Tragacanth F7 Carbopal F8 Gum arabic F9 Neem gum F10 Locust bean gum *Wet granulation

3 Page447 Evaluation of mucoadhesive tablets: Dimension (Diameter And Thickness): The Thickness and diameter permits accurate measurements and provide information on the variation between tablets. The thickness and diameter of the tablets was determined using a vernier caliper. Three tablets from each type of formulation were used and average values were calculated. Hardness: There is a certain requirement of hardness in tablets so as to withstand the mechanical shocks during handling, manufacturing, packaging and shipping. For each formulation, the hardness of 6 tablets was determined using the Monsanto hardness tester. The whole experiment was performed in triplicate. It is expressed in Kg/cm 2. Friability: Friability is the measure of tablet strength. This test subjects a number of tablets to the combined effect of shock abrasion by utilizing a plastic chamber which revolves at a speed of 25 rpm for 4 minutes, dropping the tablets to a distance of 6 inches in each revolution. A sample of preweighed tablets was placed in Roche friabilator which was then operated for 100 revolutions. The tablets were then dedusted and reweighed. Generally considered and acceptable limit is loss of less than 1 % in weight. Percent friability (% F) was calculated. Weight Variation: The weight variation test is done by taking 20 tablets randomly and weighed accurately. The composite weight divided by 20 provides an average weight of tablet. Not more than two of the individual weight deviates from the average weight by 10 % and none should deviate by more than twice that percentage. The average weight and standard deviation of the tablets were calculated. Table.2: Physico-Chemical Properties of Tablets Formu-lation Dimension Hardness Friability Weight Code Diameter Thickness (kg/cm2)** (%)* variation (%) (mm)** (mm)** *** F1 8.0± ± ± ± F2 8.0± ± ± ± F3 8.0± ± ± ± F4 8.0± ± ± ± F5 8.0± ± ± ± F6 8.0± ± ± ± F7 8.0± ± ± ± F8 8.0± ± ± ± F9 8.0± ± ± ± F10 8.0± ± ± ± *All the values are expressed as mean± SD, n=3. **All the values are expressed as mean± SD, n=6. *** All the values are expressed as mean± SD, n=20. In- Vitro Swelling Study (water uptake study): The tablets of each formulation were weighed individually (designated as W 1 ) and placed separately in petri dishes containing 2% agar gel. At regular intervals (1, 2, 3, 4, 5, 6, 7 and 8 hr), the tablets were removed from the petridishes and excess water was removed carefully by using filter paper. The swollen tablets were reweighed (W 2 ), the swelling index of each formulation was calculated using the formula [5] Where, W 2 - weight of tablet after particular time interval W 1 - initial weight of tablet

4 Page448 Table.3: Percentage swelling index of Tablets: Code Time (hours) F F ± ± ± ± ±0.28 F ± ± ± ± ±2.84 F ± ± ± ± ±1.86 F ± ± ± ± ±0.87 F ± ± ± ± ±3.54 F ± ± ± ± ±2.14 F ± ± ± ± ±2.87 F ± ± ± ± ±1.54 F ± ± ± ± ±1.18 *All the values are expressed as mean± SD, n=3 Evaluation of bio-adhesive strength of tablet: Modified physical balance method: Measurement of adhesion force was determined by using goat intestinal mucus membrane. The tissues were washed thoroughly with phosphate buffer solution (ph 6.8) then the membrane was tied to the glass slide using rubber band. The glass slide was kept in a beaker which was filled with phosphate buffer solution at 37 C±1 C in such way that buffer just reaches the surface of mucosal membrane and kept it moist. The tablet to be tested was stuck on the mucus membrane and allow for 5min for swelling and then by using clip to attach the tablet. Then the weight on the left hand side was slowly added in an increment of 0.5g till the tablet separated from the membrane. From bio-adhesive strength, the force of adhesion was calculated using the formula. [6, 7] 9.81 Fig 1: Modified physical balance Ex-Vivo Mucoadhesion Time The ex-vivo mucoadhesion time was examined after application of tablet over excised goat mucosa for 30sec after previously being secured on glass slab and was immersed in a basket of the dissolution apparatus containing around 750ml of phosphate buffer, ph 6.8 at 37 C±1 C. The paddle of the dissolution apparatus was adjusted at a distance of 5cm from the tablet and rotated at 25rpm. The time for detachment from the mucosa was recorded. [8, 9,10] In-Vitro residence time: The In-vitro residence time was determined using a locally modified USP disintegration apparatus. The disintegration medium was composed of 800ml of ph 6.75 isotonic phosphate buffer maintained at 37 C. A segment of porcine buccal mucosa, 3cm length, was glued to the surface of the glass slab, vertically attached to the apparatus. The mucoadhesive tablet was hydrated from the surface using 15ml ph of 6.8 and then the hydrated surface was brought in to the contact with the mucosal membrane. The glass slab was vertically fixed to the apparatus and allowed to move up and down so the tablet was completely immersed in the buffer solution at the lowest point and was out at the highest point. The time necessary for complete erosion or detachment of the tablet from the mucosal surface was recorded (mean of triplicate determinations). [ 11, 12, 13]

5 Page449 Table 4: Effect of bioadhesive polymers on bioadhesive strength and bioadhesive force S. No. Formulation code Mucoadhesive strength (g)* Mucoadhesive Force(N)* Ex-Vivo Mucoadhesion time (hrs)* Mucoadhesion Retention time (hrs)* 1 F1 1.53± ±0.005 Less than 1 hour Less than 1 hour 2 F ± ±0.005 More than 7 hours More than 3hours 3 F ± ±0.007 More than 7 hours More than 3hours 4 F ± ±0.008 More than 7 hours More than 3hours 5 F ± ± hours More than 3 hours 6 F ± ±0.005 More than 6 hours More than 3 hours 7 F ± ±0.005 More than 7 hours More than 3hours 8 F ± ± hours More than 3hours 9 F ± ± hours More than 3hours 10 F ± ±0.006 More than 6 hours More than 3hours *All the values are expressed as mean± SD, n=3. RESULTS AND DISCUSSION: Mucoadhesive tablets were prepared by the wet granulation method by using natural polymers such as carbopal 934, xanthan gum, karaya gum, guar gum, chitosan, neem gum, locust been gum, tragacanth and gum Arabic were prepared and all the formulations were evaluated for their various physical parameters given in the table2. Thickness and hardness of the tablets were in the range of 1.77mm-2.01mm and Kg/cm 2 respectively.the values of weight variation was within the limit. The friability of the tablets was also within the range 0.24%-0.45%. Swelling index: Batch F1-F10 formulated with the different natural polymers such as carbopal 934, xanthan gum, karaya gum, guar gum, chitosan, neem gum, locust been gum, tragacanth and gum Arabic formulations with the batchs F2-F10 and from all the formulations F7 batch (carbopal 934) shows highest value of swelling index 794% in 8hours and the formulation F10 batch (Locust been gum) shows lowest swelling index 391% the results was given in the table 3. Bio-adhesive strength: All the formulation shows good mucoadhesion. The In-vitro bioadhesive strength study was performed on the modified physical balance to measure the force (N) required for detaching the tablet and the results was given in the table 4. The bioadhesion characteristics were affected by the type of the bioadhesive polymers and viscosity of the polymer also affects the bioadhesive strength of the tablet. In all the formulations F7 formulation with the polymer carbopal 934 showes highest mucoadhesive strength and F5 formulation with the polymer chitosan shows lowest mucoadhesive strength. Ex-Vivo Mucoadhesion Time and In-vitro Retention time: Ex-Vivo Mucoadhesion time of all formulation (F1-F10) calculated by modified dissolution apparatus. In all the formulation Ex-vivo mucoadhesive time increased more than 6 hrs except formulations F5, F8, F9 with the polymers chitosan, gum Arabic, and neem gum. And In-vitro mucoadhesive retention time of all formulations (F1-F10) calculated by modified disintegration apparatus. And all the formulations show more than 3hours of In-vitro retention time. CONCLUSION: The use of mucoadhesive polymers were increased for the development of pharmaceutical formulations in recent years. Mucoadhesive polymers may provide an important tool to improve the bio availability of an active ingredient by improving the resident time at the delivery site. The various sites where mucoadhesive polymers have played an important role include buccal cavity, nasal cavity, rectal lumen, vaginal lumen and gastr intestinal tract. In present study with out drug all the natural polymers incorporated with lactose so it is used as an active ingredient.in this mucoadhesive studies with out drug the mucoadhesive strength and mucoadhesive force can be determined by natural polymers.there is no interaction between natural polymers and lactose In this study some of the natural polymers were evaluated for the following tests such as swelling index, mucoadhesive strength, mucoadhesive force, Ex-vivo mucoadhesive time and In-vitro mucoadhesive retention time and the ascending order of these polymers for the formulation of mucoadhesive system.the force of adhesion of different polymers was found in the order of gum Arabic(1.53) < neem gum (1.55)< locust bean gum(1.60) < tragacanth(1.64) < chitosan(1.71) < guar gum(1.82) < xantha gum(1.87) < karaya gum(1.92) < carbopal 934(2.27). All these polymers can be successfully used for the development of gastro retentive mucoadhesive drug delivery systems. And the use of the polymer will be depending on the half life of the active ingredient.

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