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.

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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.

Purpose: To assess the effect of polymer ratio on the quality of a novel co-processed excipient of prosopis gum and crab shell chitosan. Methods: The physicochemical properties (DSC thermogram, powder flow properties, porosity and swelling index as well as pH, viscosity and adhesive strength of 2 % w⁄v dispersions) of prosopis gum, chitosan and the three grades of co-processed excipient of prosopis gum and crab shell chitosan (Prosochit® 201, Prosochit® 101 and Prosochit® 102) were determined. Results: The three grades of the co-processed excipient of prosopis gum and crab shell chitosan (Prosochit®) were characterized by one endothermic transition each with peaks at 180 o C, 179 o C and 178 o C for Prosochit®201, Prosochit®101 and Prosochit®102 respectively. Flow properties increased with increase in proportion of chitosan. The porosity of the three grades of the new excipient was not significantly different from that of prosopis gum. Swelling indices of prosopis gum, chitosan, Prosochit® 201, Prosochit® 101 and Prosochit® 102 were 1135.53%, 14.00%, 726.33%, 677.33% and 514.00% respectively. The viscosity also decreased with increase in the proportion of chitosan. The new excipient had higher adhesive strength compared to the individual constituents (prosopis gum and crab shell chitosan). Conclusion: Prosochit® is superior to its individual constituents as a tableting excipient but its suitability for liquid formulation is reduced by increase in the proportion of chitosan.

95 % permeation in 135 min (in SGF) and 95 % permeation in 170 min (under SIF condition). Conclusion: Cashew gum is effective as a binder over a relatively wide range of concentrations to achieve fast drug release though with minimal permeation enhancement while prosopis gum is characterized by delayed drug release but enhanced permeation of the released drug.

This chapter focuses on the emulsifying properties of hemicelluloses. Hemicelluloses are gummy polysaccharides of complexity between gum and cellulose. Based on the major monosaccharide constituents of their backbone, hemicelluloses can be classified into xylans, mannans, xylogalactans and xyloglucans. Their sources include seeds, husks, straws, leaves and wood. Hemicelluloses bring about emulsification by viscosity modification and by formation of multilayered films around each globule of the dispersed phase. They have strong emulsifying power but are somehow limited by batch-to-batch variation and susceptibility to microbial and chemical degradations. These limitations are overcome by the use of purified and semisynthetic derivatives. Hemicelluloses and derivatives herein considered for their emulsifying properties include those from barley straw, wheat straw, corn fiber, locust bean, guar, soy bean, konjac, prosopis seed and afzelia seed. Hemicelluloses, as plant polysaccharides, are only second to cellulose in terms of abundance. They have superior emulsifying properties compared to the typical gums. They are amenable to many chemical modifications for the enhancement of stability and for the improvement of emulsifying properties. Hemicelluloses were not given adequate attention in the past; but this chapter shows that they are potentially useful emulsifying agents.

Objective: The objective of this study is to evaluate callinectes chitosan as a superdisintegrant in tablet formulation; superdisintegrants are incorporated into tablets at concentrations below 5% of tablet weight to effect prompt break-up of tablets after administration. Methods:Chitosan was extracted from shells of Callinectes gladiator. The polymer was characterized and then used as a disintegrant (in comparison with Ac-Di-Sol ® and corn starch) at concentrations of 2, 4 and 8% for the formulation of metronidazole tablets. The micromeritic properties of granules; and mechanical and release properties of the tablets were studied.Results: A yield of 36.7% chitosan having degree of deacetylation of 62.7% was obtained from the crab shell. Fourier Transform Infrared absorption bands at 1495 and 3240 cm -1 typical of N-H bending and stretching respectively; and endothermic peak of 159 °C typical of melting of chitosan were obtained. No adverse interaction between the chitosan and metronidazole was observed. The disintegration times of tablets containing 2, 4 and 8% chitosan were 12.2, 10.4 and 9.3 min respectively. Conclusion:Callinectes chitosan is suitable for use as a superdisintegrant in tablets. It appears to be superior to corn starch as disintegrant although less effective compared to Ac-Di-Sol ® . However, the relative cheapness and ready availability of chitosan would make it to be preferred to Ac-Di-Sol ® .