Formulation And Evaluation of Gastroretentive Floating Matrix Tablets of Metronidazole Using Khaya Ivorensis Gum
Clifford Orakwe, Collins O. Airemwen, Michael U. Uhumwangho*
This study was carried out to design and evaluate gastro-retentive floating matrix tablets (GFMTs) of metronidazole formulated using Khaya ivorensis gum. Granules were prepared by wet granulation technique using the gum at varying concentrations (2, 4, 6 and 8% w/w). Sodium bicarbonate (30%) and tartaric acid (5%) were incorporated as the gas generating agent. Formulations were either prepared alone with the Khaya ivorensis or with the addition of 1.0% w/w of acrylatemethacrylate copolymer. All granules were evaluated for micromeritic properties and compressed at an optimized compression pressure of 30 arbitrary units on the tableting machine load scale. Tablets were evaluated for hardness, friability, floating lag time, in vitro buoyancy test and drug release profiles. Release data were subjected to analysis by zero order flux, first order, Higuchi square root of time relationship and Korsmeyer equations. Results revealed that all formulated gastroretentive floating matrix granules (GFMG) were free flowing with angle of repose and Carr’s index ≤ 29.1o and ≤ 19% respectively. The floating lag time for GFMTs was ≤ 725 seconds. The in vitro buoyancy test of GFMTs formulations using the gum alone (i.e. without the incorporation of acrylatemethacrylate copolymer) were <12 h while those with acrylatemethacrylate copolymer were >12 h. All GFMG were compressible with tablet hardness between 14.1 – 45.7N while percentage friability was ≤ 0.97%. There was a significant difference in tablet hardness with increase in binder concentration (p<0.05). All formulations fitted well into Higuchi model release kinetics. Formulations KI - K3 have their exponent values <0.45, hence their release mechanism was by Fickian diffusion while for K4 and K5 their exponent values > 0.45, therefore the release mechanism for all these formulations was by non Fickian diffusion. The conclusion is that GFMTs of metronidazole have been developed using Khaya ivorensis gum which can sustain drug formulation for up to 10h.
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