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 EXPERIMENTAL Materials and Apparatus Famotidine was obtained as a gift sample from Intas Pharmaceutical, Ahmedabad. Polyvinyl alcohol was obtained from S.D. Fine Chemicals Ltd. Mumbai. Dichloromethane, ethyl acetate, acetone, acrycoat S100, chitosan were obtained from Central Drug House (Pvt) Ltd. Delhi. All other chemicals/reagents were used of analytical grade. Table 1: Different formulations of floating microspheres S. No. Code Drug: ratio Polymer Organic solvent system Polyvinyl alcohol (%w/v) 1. C1* 1:1 Dichloromethane: Ethanol 1:1 0.25 2. C2 1:2 Dichloromethane: Ethanol 1:1 0.25 3. C3 1:3 Dichloromethane: Ethanol 1:1 0.25 3. C4* 1:1 Dichloromethane: Ethanol 1.:1 0.5 3. C5* 1:1 Dichloromethane: Ethanol 1:1 1.0 4. A1 1:1 Dichloromethane: Ethanol 1:1 2.0 5. A2 1:2 Dichloromethane: Ethanol 1:1 2.0 6. A3 1:3 Dichloromethane: Ethanol 1:1 2.0 *Formulation coded with different concentration of polyvinyl alcohol (% w/v) using same drug: polymer ratio Code Buoyancy Table 2: Various formulation parameters for microspheres Mean Incorporation Husner’s size a (%) b particle efficiency percentage b ratio Carr’s index Angle of repose (θ) C1* 375.1±1.818 86.15±0.044 80.6±2.1 1.66±0.023 14.285±0.345 23.41 ° ±0.035 C2 378.7±2.914 83.15±0.011 79.01±3.3 1.146±0.059 12.79±0.421 22.43 ° ±0.581 C3 389.3±1.984 84.15±0.012 77.56±3.6 1.166±0.039 12.35±0.746 22.15 ° ±0.351 C4* 376.1±1.657 85.52±0.065 81.7±2.1 1.56±0.056 13.13±0.345 22.24 ° ±0.028 C5* 379.1±1.546 84.38±0.038 82.8±2.1 1.42±0.073 13.06±0.254 21.85 ° ±0.026 A1 380.8±2.164 83.15±0.032 76.14±2.1 1.58±0.046 13.58±0.546 22.87 ° ±0.124 A2 383.6±1.854 83.51±0.034 74.85±1.8 1.42±0.028 12.468±0.214 21.85 ° ±0.256 A3 390.6±1.931 81.35±0.016 75.56±1.9 1.35±0.075 11.845±0.587 20.85 ° ±0.428 a Mean±SD, n=10. b Mean±SD, n=3. Preparation of microspheres Microspheres were prepared by the solvent evaporation emulsification technique as employed by Struebel et al. (Struebel et al., 2003). Famotidine as model drug and polymers such as acrycoat S100 (batch A1-A3) or chitosan (batch C1-C5) was dissolved in a mixture of solvent system at room temperature to be prepare different formulation systems (Table 1). This dispersed medium was poured into 150 mL 0.1 M acidic solution containing polyvinyl alcohol as continuous medium at room temperature and subsequently stirred at ranging agitation speed for 2 h to 2
A. K. Jain et al: Continental J. Pharmaceutical Sciences 3: 1 - 6, 2009 allow the volatile solvent evaporate. The prepared microspheres were filtered, washed with distilled water and dried in vacuum. Characterization of microspheres Size and shape of microspheres: The size of microspheres was determined using a microscope (Olympus NWF 10x, Educational Scientific Stores, India) fitted with an ocular micrometer and stage micrometer. Scanning electron microscopy (SEM) (Philips-XL-20, The Netherlands) was performed to characterize the surface of formed microspheres. Microspheres were mounted directly onto the sample stub and coated with gold film (~ 200 nm) under reduced pressure (0.133 Pa). Flow properties: It was determined in terms of carr’s index (Ic) and hausner’s ratio (H R ) using following equations: H R =ρ t/ ρ b I c =ρ t- ρ b/ ρ t Figure 1: Scanning electron microscopy photographs of floating microspheres The angle of repose (θ) of the microspheres, which measure the resistance to particle flow, was determined by fixed funnel method by using following equation: tan θ=2H/D Where, 2H/D is the surface area of the free standing height of the microspheres heap that formed after making the microspheres flow from the glass funnel. Buoyancy percentage: Microspheres (0.3 g) were spread over the surface of a USP XXIV dissolution apparatus (type II) filled with 150 ml 0.1 mol L –1 hydrochloric acid (USP, 2000). The medium was agitated with a paddle rotating at 500 rpm for 12 h. The floating and the settled portions of microspheres were recovered separately. The floated microspheres were collect by decantation and weighed. Buoyancy % = Floated mass of prepared microspheres / Total mass of prepared microspheres Incorporation efficiency: To determine the incorporation efficiency, prepared microspheres were taken, thoroughly triturated in pestle mortar equivalent as drug used in formulation and suspended in a 5 ml of dichloromethane as dissolving medium. The suspension was suitably diluted with water and filtered to separate shell fragments. Drug content was analyzed spectrophotometrically at 265 nm. In-vitro drug release: A USP basket apparatus has been used to study in vitro drug release from microspheres (Singh and Kim, 2000; Dinarvand et al., 2002; Abrol et al., 2004). In the present study, drug release was studied using a modified USP XXIV dissolution apparatus type I (basket mesh # 120, equals 125 µm) at 100 rpm in distilled water and 0.1 mol L –1 hydrochloric acid (pH 1.2) as dissolution fluids (900 ml) maintained at 37 ± 0.5 °C. Withdrawn samples (10 ml) were analyzed spectrophotometrically as stated above. The volume was replenished with the same 3
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