DESIGN AND DEVELOPMENT OF BIOADHESIVE MULTIPARTICULATE DRUG DELIVERY SYSTEM

Transcription

1 DESIGN AND DEVELOPMENT OF BIOADHESIVE MULTIPARTICULATE DRUG DELIVERY SYSTEM Harsulkar Amol 1 * and S.A. Sreenivas 2 1 Department Pharmaceutical Sciences, J.J.T. University, Jhunjhunu, Rajasthan 2 Grurunanak Institute of Pharmacy, Ibrahimpatnam. Dist. RR, Hydrabad ABSTRACT: In recent years, Multiparticulate dosage forms such as matrix or coated pellets or microparticles have gained in popularity for a variety of reasons.. Hence, the present study aims toward formulation and evaluation of mucoadhesive multiparticulate drug delivery system, which can provide sustained release of the drug Cinnarizine using Ethyl cellulose in combination with Carbopol 934P and/or HPMC K4M polymers in different proportions and combinations by emulsification/solvent evaporation technique. The microspheres were evaluated for micromeritic studies, drug entrapment, in vitro bioadhesion, in vitro release study and stability studies. From the results, it was concluded that Mucoadhesive microspheres of A2 batch comprising 63.5mg Ethyl cellulose, 0.65mg Carbopol 934P and 50mg Cinnarizine were found to be satisfactory in terms of drug release, bioadhesiveness and drug entrapment. In vitro drug release of 97.46% in 12 hours of this batch indicated that this formulation was the most promising one from other batches which is suitable for twice a day medication. Keywords: Cinnarizine, bioadhesive, Multiparticulate, microspheres, emulsification. INTRODUCTION: Carrier technology offers an intelligent approach for drug delivery by coupling the drug to a carrier particle such as microspheres, nanoparticles, liposomes, etc. which modulates the release and absorption characteristics of the drug. Microspheres constitute an important part of these particulate DDS by virtue of their small size and efficient carrier characteristics. However, the success of these novel DDS is limited due to their short residence time at the site of absorption. [1] It would, therefore, be advantageous to have means for providing an intimate contact of the DDS with the absorbing membranes. It can be achieved by coupling bioadhesion characteristics to microspheres and developing novel delivery systems referred to as bioadhesive microspheres. [2] Bioadhesive microspheres include microparticles and microcapsules (having Corresponding Author* Harsulkar Amol 85 P a g e

2 a core of the drug) of µm in diameter and consisting either entirely of a bioadhesive polymer or having an outer coating of it, respectively. [3] In recent years, Multiparticulate dosage forms such as matrix or coated pellets or microparticles have gained in popularity for a variety of reasons. Considerable research efforts have been spent on oral sustained or controlled release multiparticulate drug delivery system due to its advantages over monolithic dosage [4, 5] forms: It has lower potential for dose dumping and it minimizes the risk of local irritation. It avoids fortuitous (all or none) emptying process. It reduces patient-to patient variability i.e. inter-subject variability It provides greater flexibility to the formulators It distribute more uniformly in the gastrointestinal tract, thus resulting in more uniform drug absorption. Advantages of Bioadhesive [6-8] Microsphere: 1) The bioadhesive microspheres can be used not only for controlled release but also for targeted delivery of the drugs to specific sites in body. 2) Efficient absorption and enhanced bioavailability of the drugs due to a high surface to volume ratio, a much more intimate contact with the mucus layer, specific targeting of drugs to the absorption site achieved by anchoring plant lectins, bacterial adhesins and antibodies, etc. on the surface of the microspheres. 3) Bioadhesive microspheres can be tailored to adhere to any mucosal tissue including those found in eye, nasal cavity, urinary, colon and gastrointestinal tract. 4) Offering the possibilities of localized as well as systemic controlled release of drugs. 5) Increased residence time and decreased frequency of administration. MATERIALS AND METHODS: Materials: Cinnarizine, Ethyl cellulose, HPMC K4M, Carbopol 934P, Acetone, Petroleum Ether, Liquid Paraffin Method: Preparation of bicoadhesive microspheres. [9] The microspheres were prepared by emulsification/evaporation technique. Firstly, the polymer ethyl cellulose was dissolved in acetone. Then the drug and carbopol 934P/HPMC K4M were added to the ethyl cellulose solution under magnetic stirring and the mixture was blended for 8hrs. Then the suspension was slowly dispersed in liquid paraffin at a stirring rate of 1000 rpm and 37 o C. After 2 hrs of emulsification, the acetone was evaporated until the microspheres were formed. The microspheres were washed with petroleum ether for 3-4 times and dried. The prepared formulations are given in table no. 1 & 2. Micromeritics Studies of Bioadhesive [10, 11] Microspheres: The microspheres were characterized by their micromeritic properties, such as particle size, tapped density, compressibility index, and flow property. 86 P a g e

3 Percentage recovery (i.e. % Yield) of [11, 12] microspheres formed: The prepared microspheres with a size ranging from 200 to 550 m were collected and weighed. The measured weight of prepared microspheres was divided by the total amount of drug and polymers used for the preparation of the microspheres and finally multiplied by 100 gave the total percentage yield of mucoadhesive microspheres. In-vitro Bioadhesive study of microspheres: Briefly, 12 Spraque-Dawley rats were fasted overnight and dissected immediately after being sacrificed. The stomach of the rats was removed and cut into pieces 2 cm long and 1cm wide and were rinsed with 2 ml physiological saline. One hundred microspheres were scattered uniformly on the surface of the stomach mucosa. Then, the mucosa with the microspheres was placed in a chamber maintained at 93% humidity and room temperature. After 20 min, the tissues were taken out and fixed on a polyethylene support at an angle of 45 o. The stomach was rinsed with ph 1.3 HCl-physiological saline solution for 5 min at a rate of 22 ml/min. The microspheres remaining at the surface of gastric mucosa was then counted, and the percentage of the remaining microspheres was calculated and statistically analyzed using F ANOVA. Drug Loading or Incorporation efficiency (Drug Content determination): Accurately weighed mucoadhesive microspheres equivalent to 50 mg of drug were mechanically busted. These powders were dissolved in 100ml of 1.2 ph buffer and filtered through Whatmann Filter Paper No.49. Then 1ml of this solution was diluted to 100ml and the absorbance was noted at 254 nm against 1.2 ph buffer as a blank. The drug content was calculated from standard curve. Placebo microspheres were used as reference. The percentage drug retained was calculated by the formula C cal % Drug entrapment = x 100 C Th C cal. = Calculated drug concentration C Th. = Theoretical drug concentration Dissolution test (in vitro-drug release) of microspheres: [13] In the present study, the standard six stations USP paddle (apparatus I) method was used. The microspheres were placed in a non-reacting muslin cloth. The muslin cloth was tied with a nylon thread to avoid the escape of any microspheres, and then tied to the paddle and dipped in the dissolution medium. The dissolution medium used was 900ml of ph 1.2 buffer and phosphate 7.4pH separately for Cinnarizine which was filled in a dissolution vessel and the temperature of the medium was set at C and rotational speed of paddle was set at 100 rpm. The 5 ml of sample was withdrawn at predetermined time interval for 12 hours and same volume of fresh medium was replaced. The withdrawn sample was diluted and analyzed by UV-Vis spectrophotometer at the respective max values for Cinnarizine (254nm). The 87 P a g e

4 content of drug was calculated using the equation generated from standard curve. Formulation of capsule for the study: [14] A weighed quantity of the Drug loaded bioadhesive microspheres were filled in the appropriate size capsule. Capsules of 2, 4, 5 sizes were found to be appropriate for filling the capsule. The contents were filled in the tared capsule, which were then reweighed. Care was taken to fill the capsule completely in order to maintain a uniformity of weight. Evaluation study was conducted to know uniformity of weight, content uniformity, disintegration and stability. The capsules were successfully prepared by filling bioadhesive microspheres and were subjected to evaluations and are given in table no.3. Dissolution Studies of Capsules: In vitro release studies of batches of capsules containing mucoadhesive microspheres with the drug loaded was conducted in 1.2pH and 7.4pH buffer in six station USP Dissolution apparatus II separately for 12 hrs. RESULTS AND DISCUSSION: Micromeritics Studies of Mucoadhesive Microspheres: The various batches has the average particle size in the range of 240 m to 520 m. whereas Carr s index in between 2-6% and Hausner ratio with in 1.06 and angle of repose was found within the range of 15 0 to 25 0, which is a appreciable limit for microspheres to show flow property while formulating in the dosage form. Percentage recovery (i.e. % Yield) of microspheres formed: The maximum percentage yield was obtained in B1 batch and was noted to be 82.3% among all the batches. It was found that average percentage yield was greater than 65% for all. The Percentage yield of microspheres formed is given in table - 4. In-vitro Bioadhesive Study: The maximum percentage adherence was found for A2 batch and was noted to be 96.33% among all the batches. It was found that average percentage adherence was greater than 85% for all. And F ANOVA test was conducted between the batches and was statistically found to be significant. The maximum percentage adherence for all batches is shown in table -5. Percentage Drug entrapment: The microspheres of batch A2 formulation showed an entrapment of 84.6% while other formulations showed lesser entrapment than this formulation. Dissolution (In-vitro Drug release) studies Release of the drug from mucoadhesive microspheres was evaluated at ph 1.2 and 7.4 for 12 hrs. The drug release rate of Cinnarizine was almost linear with time for the first 10 hrs and gradually decreased afterwards in 1.2pH and not more than 60% is released in the 7.4pH buffer and shown in table -6. Evaluation of Capsules containing Microspheres: The capsules were evaluated for general appearance, weight variation, content uniformity test and In-vitro drug release and showed good results. 88 P a g e

5 Morphological results with Scanning Electron Microscopy (SEM) of optimized batch of mucoadhesive microspheres: Morphology of microspheres was examined by scanning electron microscopy. The smooth surface of such microspheres as seen by SEM might be due to this complete homogeneity of drug and polymers. The outer surface of the microsphere was smooth and dense. In the case of these microspheres, the distinct domains of the size and of spherical geometry- attributed to encapsulation of the drug within the matrix- were observed. The view of the microspheres showed a spherical shape with a smooth surface morphology. The inside of the microspheres was completely filled, indicating that complexation had occurred everywhere within the microsphere. The SEM photographs of optimized microspheres at various magnifications are shown in Fig.-1. CONCLUSION: Literature survey on mucoadhesive drug delivery was carried out. And the drug is having short Biological half life i.e. 3 to 6 hrs, low dose that is suitable for sustained release dosage form and that s why the drug Cinnarizine was selected for the present work. The Preformulation Studies such as Physical Characteristics, Solubility, Melting Point, IR Studies, Loss on Drying, Assay have been conducted and the results comply with the standards. Various formulations of sustained release mucoadhesive microspheres of Cinnarizine were developed using various polymers viz, Ethyl cellulose in combination with Carbopol 934 P or HPMC K4M in different proportions and combinations by emulsification/solvent evaporation technique. The microspheres were evaluated for micromeritic studies, drug entrapment, in vitro mucoadhesion, in vitro release study and stability studies. The microspheres of batch A2 had considerable drug entrapment along with considerable mucoadhesion and in vitro drug release. It was observed that microspheres of all batches followed the Non-Fickenian release profiles. Microspheres of Batch A2 was selected as an optimum batch and evaluated for further parameter like accelerated stability study, IR spectroscopic studies, SEM studies and DSC studies. SEM, IR and DSC studies show positive results for optimized batch. Microspheres of batch A2 did not show any physical or chemical interaction between drug and polymer, which was concluded after showing similar peaks of drug in microspheres formulation from the IR and DSC Studies. From the results, it was concluded that Mucoadhesive microspheres of A2 batch comprising 63.5mg Ethyl cellulose, 0.65mg Carbopol 934P and 50mg Cinnarizine were found to be satisfactory in terms of drug release, bioadhesiveness and drug entrapment. A maximum in vitro drug release of 97.46% in 12 hours of this batch indicated that this formulation was the most promising one as the extent of drug release from this formulation was high as compared to other formulations, which is suitable for twice a day medication. Results of in-vitro bioadhesive 89 P a g e

6 study of A2 Batch ( ) indicate that this formulation was having considerable bioadhesion strength. REFERENCES: 1. Jaspreet Kaur V, Kaustubh T, Sanjay G. Review Bioadhesive microspheres as a controlled drug delivery system,. Int. J.Pharm,2003; 255: Mathiowitz, E., Jacob, J.S., Jong, Y.S., Carino, G.P., Chickering, D.E., Chaturvedi, P., Santos, C.A., Morrell, C., Bassett, M., Vijayaraghavan, K., Biologically erodable microspheres as potential oral delivery systems. Nature 386, Ghosh,A., Nath L.K.,Dey B.K.,Roy, P.,A study on the effect of different polymer on frusemide loaded calcium alginate micropellets prepared by inotropic gelation technique Indian J. Pharm. Edu.Res.,2007,41(4), Sanjay Garg, Shringi Sharma, Gastroretentive Drug Delivery Systems, Business Briefing: Pharmatech Drug delivery System, 2 nd Edition, Revised and expanded, 50, Mercel Dekker Inc., Chawla G., Gupta P., KoradiaV. and Bansal A. K. Gastroretention: A Means to Address Regional Variability in Intestinal Drug Absorption July 2003, Chowdary K.P.R., Srinivas L. Mucoadhesive drug delivery system: A review of current status; Indian Drugs; 37:9,2000; Tayade.P, Gastro-retentive drugs: A review NDDS, Express Pharma Pulse, Zhepeng Liu, Weiyue Lu, Lisheng qian, Xuhui Zhang, Pengyun Zeng, Jun Pan, Invitro and Invivo studies on mucoadhesive microspheres of amoxicillin, J.Cont.rel. 102 (2005) Chein.W.Yie, Novel Lachman L., Libermann H. A., Kanig J. L., The theory and practice of industrial pharmacy, 3 rd edition, Lea and Febiger Philadelphi, 1986; Aulton M. E., Pharmaceutics, The science of dosage form design, Churchill Livingstone, 1989; Singh B. N., Kim K. H. Floating drug delivery systems: an approach to oral controlled drug delivery via gastric retention Journal of Controlled Release 63, 2000; Indian Pharmacopoeia, 1996; A , Ansel H.C., Loyd.A, Popovich.N.G., Pharmaceutical Dosage form and drug delivery system 7 th Edition ;60, P a g e

7 Table 1: Using Polymer combination: Carbopol/HPMC and EC, Solvent: Acetone S.N. Drug (g) Cinnarizine Carbopol/HPM C + EC (g) Solvent (Acetone) Speed of (RPM) Rotation Temp. ( C) Rejected(R) / Selected (S) R R R R R S Table 2: Drug and Polymer combination in solvent Acetone: Batches A1 A2 A3 A4 B1 B2 B3 B4 Ingredients (mg) Ethyl cellulose Carbopol 934P HPMC K4M Cinnarizine Table 3: Formulation of Capsule single unit dosage form: Batches of Micro balloons % Yield Micro balloons Drug entrapped (mg) Microspheres Wt. (mg) Capsule size A A A A B B B B P a g e

8 Table 4: Percentage yield of microspheres Batch no. Percentage yield A A A A B B B B Table 5: Percentage adhered microspheres to the Surface of stomach mucosa of rat Batch % adhered (mean ± SD) A A A A B B B B Table 6: Cumulative Release of All Batches of Mucoadhesive Microspheres at 7.4 ph buffer Time (hrs) PERCENT CUMULATIVE RELEASE A1 A2 A3 A4 B1 B2 B3 B P a g e

9 SEM 1 SEM 2 SEM 3 SEM 4 Figure 1: SEM Photomicrographs of Mucoadhesive Microspheres SEM 1 shows group of mucoadhesive microspheres at 250X. SEM 2 shows surface of single spherical shaped mucoadhesive microspheres at 1000X SEM3 shows inside of microspheres at 1000X. SEM4 shows cryotommed section of microspheres at 2500X 93 P a g e