Purification, physicochemical and formulation properties of shea (Vitellaria Paradoxa) Gum.

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This study focused on the purification, physichochemical and formulation properties of Shea (vitellaria paradoxa) gum. The crude gum was purified and the yield obtained was 63.26%. Crude and purified Shea gums were evaluated for their physicochemical properties and were found to have satisfactory moisture content and insoluble matter. Atomic absorption spectrophotometric analysis of the gums showed that the crude gum had higher metallic ion and protein content than the purified gum which may be attributed to the purification process. The gums had relatively high levels of calcium, followed by magnesium, iron, zinc, potassuim and sodium. Different concentrations of the gum were analysed for their rheological properties and were found to exhibit pseudoplastic flow.The binding property of Shea gum was compared to that of acacia, a standard binding agent. The flow properties of the granules were evaluated and the physical properties of the compressed tablets, namely uniformity of weight, hardness, friability, and disintegration time, assay of content and dissolution rate determined. The granules had good flow properties as evidenced by their Hausner ratio, angle of repose and Carr’s index values. The gum was successfully employed as a binding agent in Paracetamol tablet formulations with different concentrations of Shea gum and acacia gum at the same concentration. The study showed that Shea gum can be successfully employed as a binder at concentrations between 5% w/v and 20% w/v and the binding effect was found to be comparable to the binding effect of the same concentration of acacia.The suspending property of the gum was investigated by assessing parameters such as rate of sedimentation, apparent viscosity and ease of redispersibility of paracetamol suspensions prepared with concentrations of 1% w/v to 4% w/v shea gum and compared with those prepared with acacia gum at the same concentration. Suspensions were successfully prepared using the gum, but the sediment showed a tighter packing as the concentration of the gum used was increased. Shea gum proved more efficient as a suspending agent than acacia gum. The emulsifying property of the gum was also investigated by preparation of emulsions using different classes of oils and employing the wet and dry gum methods of preparation. The ratio of oil to water to gum for the preparation of primary emulsion was determined for the oils. The stability of the emulsions was assessed and an improvement in the stability was attempted using homogenization, a surface active agent, and the addition of a thickening agent. The results obtained demonstrated that emulsions could be prepared with the mineral oil and fixed oil and volatile oil with ease. All the emulsions stabilized by homogenization creamed on the third day, but creaming was reduced by addition of very low concentrations of a thickening agent, xanthan gum at low concentrations of between 0.1% w/v and 0.2% w/v. The addition of a surface active agent (Tween 60) also reduced the creaming of the emulsions at low concentrations of between 0.001% w/v and 0.004% w/v.
A Thesis submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the Degree of Master of Philosophy in Pharmaceutics, June-2012