Vol 3 - Cont J Pharm Sci - Wilolud Journals

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A. K. Jain et al: Continental J. Pharmaceutical Sciences 3: 1 - 6, 2009 amount of fresh dissolution fluid each time to maintain the sink condition. All experiments were performed in triplicate. Linear regression was used to analyze the in vitro release mechanism. Statistical analysis: Experimental results were expressed as mean ± SD. Student’s t-test and one-way analysis of variance (ANOVA) were applied to check significant differences in drug release from different formulations. Differences were considered to be statistically significant at P< 0.05. RESULTS AND DISCUSSION Floating microspheres were prepared by the solvent evaporation method by using acrycoat S100 and chitosan (Table 1). The SEM photographs showed that the fabricated microspheres were spherical with a smooth surface and exhibited a range of sizes within each batch (Fig. 1). The microspheres floated for prolonged time over the surface of the dissolution medium without any apparent gelation. Buoyancy percentage of the microspheres was shown in Table 2. Figure 2: Effect of chitosan polymeric concentration on in vitro drug release from floating microspheres (bars represents mean±SD; n=3) Microspheres were prepared using different polymers with gradually increasing polymer concentration and same polymer with variability in concentration of PVA in combination with a fixed concentration of drug to assess the effect of polymer concentration on the size of microspheres. The mean particle size of the microspheres significantly increased with increasing cellulose acetate concentration (p < 0.05) and was in the range 375.1±1.818 to 389.3±1.984 µm (Table II). The viscosity of the medium increases at a higher polymer concentration resulting in enhanced interfacial tension (Reddy et al., 1990; Ishizaka, 1981). The size of prepared microsphere was change due to variability in concentration of PVA, as concentration of PVA increase size of microspheres increase but incorporation efficiency was reduced. The same concentration of polymer with changing concentration of PVA, buoyancy percentage and period was increase till to 18 h. In vitro FM release studies were performed in 0.1 mol/L hydrochloric acid for 18 h. The cumulative release of FM significantly decreased with increasing polymer concentration (p < 0.05, Fig. 2, 3) because of clumping of polymer on surface of microspheres. The increased density of the polymer matrix at higher concentrations results in an increased diffusional path length. This may decrease the overall drug release from the polymer matrix because higher gelation of surface. Furthermore, smaller microspheres are formed at a lower polymer concentration and have a larger surface area exposed to dissolution medium, giving rise to faster drug release. The data obtained for in vitro release were fitted into equations for the zero-order, first-order and Higuchi release models (Costa and Lobo, 1987; Wagner, 1969; Schefter, 1963). The interpretation of data was based on the value of the resulting regression coefficients. The in vitro drug release showed the highest regression coefficient values for Higuchi’s model, indicating diffusion to be the predominant mechanism of drug release. in-vivo floating behavior will be discussed in future for in-vitro and in-vivo co-relation. 4
A. K. Jain et al: Continental J. Pharmaceutical Sciences 3: 1 - 6, 2009 CONCLUSIONS In vitro data obtained for floating microspheres of famotidine showed excellent floatability, good buoyancy and prolonged drug release. Microspheres of different size and drug content could be obtained by varying the formulation variables. Diffusion was found to be the main release mechanism. Thus, the prepared floating microspheres may prove to be potential candidates for multiple-unit delivery devices adaptable to gastric disease. ACKNOWLEDGEMENTS The authors acknowledge the Director, Bhupal Noble’s College of Pharmacy, Udaipur, Rajasthan. Figure 3: Effect of acrycoat S100 polymeric concentration on in vitro drug release from floating microspheres (bars represents mean±SD; n=3) REFERENCES Abrol S, Trehan A, Katare OP. (2004): Formulation, characterization, and in vitro evaluation of silymarin-loaded lipid microspheres. Drug Deliv., 11: 185-191. Costa P, Lobo JMS. (1987): Modeling and comparison of dissolution profiles. Eur. J. Pharm. Sci., 39: 39-45. Deshpande A, Rhodes CT, Shah NH, Malick AW. (1996): Controlled-release drug delivery systems for prolonged gastric residence: an overview. Drug Dev. Ind. Pharm., 22: 531-539. Dinarvand R, Mirfattahi S, Atyabi F. (2002): Preparation, characterization and in vitro drug release of isosorbide dinitrate microspheres. J. Microencaps., 19: 73-81. Gladiziwa U, Klotz U. (1993): Pharmacokinetics and pharmacodynamics of H2 receptor antagonists in patients with renal insufficiency. Clin. Pharmacokinet., 24: 319-332. Ishizaka T. (1981): Preparation of egg albumin microspheres and microcapsules. J. Pharm. Sci., 70: 358-361. Joseph NJ, Lakshmi S, Jayakrishnan A. (2002): A floating-type oral dosage form for piroxicam based on hollow polycarbonate microspheres: in vitro and in vivo evaluation in rabbits. J. Control. Rel., 79: 71-79. Kawashima Y, Niwa T, Takechi H, Hino T, Itoh Y. (1992): Hollow microspheres for use as floating controlled drug delivery systems in the stomach. J. Pharm. Sci., 81: 135-140. Lee JH, Park TG, Choi HK. (1999): Development of oral drug delivery system using floating microspheres. J. Microencaps., 16: 715-729. Moes AJ. Gastroretentive dosage forms. (1993): Crit. Rev. Ther. Drug Carrier Syst., 10: 143-195. Muthusamy K, Govindarazan G, Ravi TK. (2005): Preparation and evaluation of lansoprazole floating micropellets. Ind. J. Pharm. Sci., 67: 75-79. 5
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