Characterization of a polymer is essential for determining its suitability for a particular purpose. Thermochemical properties of cashew gum (CSG) extracted from exudates of Anacardium occidentale L. and khaya gum (KYG) extracted from exudates of Khaya senegalensis were determined and compared with those of acacia gum BP (ACG). The polymers were subjected to different thermal and chemical analyses. Exudates of CSG contained higher amount of hydrophilic polymer. The pH of 2% w/v gum dispersions was in the order KYG < CSG < ACG. Calcium was the predominant ion in CSG while potassium was predominant in KYG. The FTIR spectra of CSG and KYG were similar and slightly different from that of ACG. Acacia and khaya gums exhibited the same thermal behaviour which is different from that of CSG. X-ray diffraction revealed that the three gums are the same type of polymer, the major difference being the concentration of metal ions. This work suggests the application of cashew gum for formulation of basic and oxidizable drugs while using khaya gum for acidic drugs.

This study was aimed at evaluating chitosan-microcrystalline cellulose blends as direct compression excipients. Crab shell chitosan, α-lactose monohydrate, and microcrystalline cellulose powders were characterized. Blends of the microcrystalline cellulose and chitosan in ratios 9 : 1, 4 : 1, 2 : 1, and 1 : 1 as direct compression excipients were made to constitute 60% of metronidazole tablets. Similar tablets containing blends of the microcrystalline cellulose and α-lactose monohydrate as well as those containing pure microcrystalline cellulose were also produced. The compact density, tensile strength, porosity, disintegration time, and dissolution rate of tablets were determined. Chitosan had higher moisture content (7.66%) and higher moisture sorption capacity (1.33%) compared to microcrystalline cellulose and lactose. It also showed better flow properties (Carr's index of 18.9% and Hausner's ratio of 1.23). Compact density of tablets increased but tensile strength decreased with increase in the proportion of chitosan in the binary mixtures. In contrast to lactose, the disintegration time increased and the dissolution rate decreased with increase in the proportion of chitosan. This study has shown that chitosan promotes flowability of powder mix and rapid disintegration of tablet. However, incorporation of equal proportions of microcrystalline cellulose and chitosan leads to production of extended-release tablet. Therefore, chitosan promotes tablet disintegration at low concentration and enables extended-release at higher concentration.

No abstract

Objective: Afzelia africana gum has been shown to possess surface activity. It is a good alternative to sodium carboxy methylcellulose in terms of suspending properties. This work was aimed at evaluating the emulsifying properties of the gum in liquid paraffin emulsion.Methods: Liquid paraffin emulsions (200 ml each) were prepared with different concentrations (1, 2, 3, 5 and 10 % w/v) of afzelia gum as an emulsifying agent. Similar preparations containing standard acacia gum at corresponding concentrations were also made. Liquid paraffin emulsions (200 ml each) were equally prepared using 60 ml liquid paraffin as the oily phase and 6 g of various combinations of afzelia gum and tween 80 as emulsifier blends. The emulsifier blends were of ratio 1:5, 1:2, 1:1, 2:1 and 5:1. The preparations were assessed for density and viscosity; and then for stability after 5 d of storage. Results:The viscosity of emulsion containing 10 % w/v afzelia gum was 668.90 mPa.s while that of an emulsion containing the same concentration of acacia gum was 23.56 mPa. s. Emulsion containing 3 % w/v afzelia gum (having a creaming index of 16 %) was found to be more stable compared to the emulsion containing 10 % w/v acacia gum (having creaming index of 28 %). The viscosity and stability of emulsions containing emulsifier blends of afzelia gum and tween 80 increased with increase in the proportion of afzelia gum. Conclusion:The gum is suitable for use at a concentration of 3 % w/v as an emulsifier in 30 % v/v liquid paraffin emulsion, and it is about three times better than acacia gum as an emulsifier. It is a good alternative to standard acacia gum for emulsification.