Acta Pharm. 53 (2003) 49-56

Effects of the diluent type on the compressional characteristics of the mixed stem bark extract of Anogeissus leiocarpus and Prosopis africana tablet formulation

C. Y. ISIMI,^1* R. N. NASIPURI¹, J. B. OJILE,² Y. K. E. IBRAHIM² and M. EMEJE ¹

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¹Department of Pharmaceutical Technology and Raw Material Development, National Institute for Pharmaceutical Research and Development, P.M.B. 21, Garki, Abuja, Nigeria
²Department of Pharmaceutics and Pharmaceutical Microbiology, Ahmadu Bello University, Zaria, Nigeria

The hot water extract of a mixture of stem barks of Anogeissus leiocarpus and Prosopis africana was formulated into tablets using the wet granulation method of massing and screening. The Heckel equation was used to study the compaction characteristics of the extract formulated with lactose (water-soluble) or magnesium carbonate (water-insoluble) as diluent. Granules prepared using magnesium carbonate were found to exhibit two stages of deformation - an initial fragmentation followed by plastic flow while those formulated with lactose consolidated mainly by plastic deformation. Compressibility profiles of the formulations were affected by the diluent type. Tensile strength of granules formulated with magnesium carbonate was found to increase as the compression pressure increased from 56.6 to 113.2 MN m^-2 while the tensile strength of tablets formulated with lactose had its maximum at a compression force of 84.9 MN m^-2.

Keywords: Anogeissus leiocarpus (Combretaceae), Prosopis africana (Mimosaceae), stem bark extract, diluent, compaction characteristics, Heckel equation, compressibility, tensile strength, granules, tablets