Investigation into the Use of the Fruit Pulp of Parkia Biglobosa (African Locust Bean) As an Excipient in Solid Pharmaceutical Dosage Forms

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The world today is increasingly interested in natural drugs and excipients. Natural materials have advantage over synthetic because they are relatively non toxic, less expensive and readily available. This study sought to process Parkia biglobosa fruit pulp, evaluate its physico-chemical and functional properties; formulate and assess its effects in tablets using Acacia gum and Sodium starch glycolate as reference binder and disintegrant, respectively in paracetamol tablet formulations. The P. biglobosa fruits were obtained from four different locations in Northern Ghana and processed. The most suitable sample was selected as a representative sample based on their organoleptic properties and results of preliminary phytochemical and physicochemical tests. Further phytochemical analysis were then carried out on the chosen sample. The effects of the fruit pulp as a binder and disintegrant were investigated on paracetamol tablets formulations. Granules were formulated by the wet granulation method. The granules were compressed on manually controlled single punch tableting equiptment. Reference batches of tablets using Acacia gum as a binder and Sodium starch glycolate as a disintegrant were also prepared. Post compression tablet parameters including: tablet thickness, uniformity of weight, friability, hardness, disintegration time and dissolution were assessed. The results of the phytochemical screening indicated presence of carbohydrates, reducing sugars, saponins and glycosides but were negative for alkaloids, starch and tannins. The P. biglobosa fruit pulp had a pH of 6.31 and was soluble in water but insoluble in organic solvents such as acetone, alcohol and chloroform. By all the indicators, Tapped density (0.24 g/ml), Bulk density (0.18 g/ml), Angle of repose (45.0o), Hausner’s ratio (1.67), Carr’s index (40 %) the fruit pulp did not show satisfactory inherent flow properties. The particle size data revealed fine particles with a geometric mean diameter of 420 μm. The fruit pulp had a very high water binding capacity (446 %) holding up to about five times its own weight of water and corroborates with its swelling profile (4.25) suggesting it could serve as a good disintegrant. Its high moisture sorption value (42.50 %) however, indicates its susceptibility to atmospheric moisture and moisture induced changes which may affect flow, compression behaviour V and mechanical strength of tablets. The proximate data of P. biglobosa fruit pulp ( moisture content 8.66 % , ash 2.40 % , crude fat 0.13, crude fibre 8.75 %, protein 6.64 % , carbohydrate 76.80 %, and sugar 3.66oBrix) showed it could be a good source of macronutrients. The pasting profile of the P. biglobosa fruit pulp (pasting temperature 60.70oC, breakdown viscosity 7.5 RVU, setback viscosity 15 RVU, peak viscosity 9.0 RVU and final viscosity 15.50 RVU) indicated the absence of starch and lack of inherent viscosity. The tablets of all the batches had uniform thickness and passed the BP uniformity of weight test. The batches of tablets formulated with 1 %, 3 % w/w concentratons of P. biglobosa fruit pulp as binder (and 2 % w/w concentration of the fruit pulp as disintegrant ) failed the BP hardness test. Tablets of with 1 % w/w concentration of the fruit pulp as binder failed the BP friability test. All others passed it. The tablets with P. biglobosa fruit pulp and Acacia gum as binders passed the BP disintegration test whiles those with the fruit pulp as disintegrant failed. Hence P. biglobosa fruit pulp may not be a good disintegrant. On the basis of drug release the tablets prepared with P. biglobosa fruit pulp as a binder at 5%w/w released over 90 percent of the drug within 45 minutes which compared well with the release profile of Acacia gum at the same binder concentration. Tablets with 5% w/w concentration of P. biglobosa pulp and Acacia gum showed comparative effectiveness as a binder to paracetamol powder. Thus P. biglobosa fruit pulp was found useful as a binder in the formulation of paracetamol tablets and demonstrated its potential for application in the pharmaceutical industry, especially as a thickener and binding agent.
A thesis submitted to the Department of Pharmaceutics, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the degree of Master of Philosophy in Pharmaceutics