Physical and tabletting characterization of chitosan obtained from

Physical and tabletting characterization of chitosan obtained from various sources n n Chitosan is a biodegradable and biocompatible biopolymer leading to draw many research’s interests. It has been investigated as an excipient in the pharmaceutical field to be used in direct compression, as a disintegrant for the improvement of drug dissolution, as a matrix material for the production of controlled release solid dosage forms. The physical properties of chitosan is mainly characterized by two parameters: degree of acetylation and molecular weight. In this study, the possible use of chitosan from two different sources with variation in these two parameters as directly compressible excipient for modification of drug release were examined. Five different chitosan products (wako 10, wako 100, wako 500, and 903 from shell chitin, and sacchachitosan from sacchachitin) varied in physical properties were selected for evaluation of main factors influencing the success of direct compression. Powder only and a series ratio of binary mixture with acetaminophen were prepared for characterization with the measurement of powder rheology, compaction profiles, heckel plot analysis, and drug dissolution in three different conditions (simulated gastric fluid, p. H-changing medium, and simulated intestinal fluid). Preliminary results demonstrated that the compressibility of sacchachitosan was so poor to form tablet even increasing compression force to a higher value. Compaction profiles showed that there was insignificant difference in profiling parameters including effective work and ejection force for all chitosan products compared. Yield pressure calculated from Heckel plot for each product also demonstrated to be insignificantly different. However, the tensile strength of tablets prepared with wako 100 and wako 10 was much higher than that with wako 500 and 903. Degree of elastic recovery might be used to explain why wako 100 and wako 10 could make tablets stronger. The compressibility for a series of binary mixture of acetaminophen and chitosan of wako 100 and wako 10 were determined. There also shows insignificant difference in degree of elastic recovery and effective work. With increasing the percentage of chitosan in the formulation, the ejection force of tablets decreased and the tensile strength of tablets increased correspondingly. The yield pressure of tablets decreased with increasing percentage up to 70% of chitosan in tablet formulation as well for all types of chitosan examined, and then increased afterward with increasing the percentage of chitosan. The drug release of acetaminophen from binary mixture of acetaminophen and wako 100 (or wako 10) was examined in three different media. The drug release follows a sustained manner in simulated gastric fluid (p. H=1. 2) when the percentage of chitosan in tablet formulation is greater than 30% for wako 10 and 10% for wako 100. This is expectedly due to the gelling effect of chitosan in contact with acidic environment. Since that, the higher viscosity of chitosan is used, the less amount of chitosan is needed to achieve the sustained effect. Dissolution under p. H-changing medium, the sustainability of drug release is even extended to be longer than 24 hours after changing to simulated intestinal fluid (p. H=6. 8). This might be ascribed to the insolubility of chitosan in neutral p. H leading to the formation on the tablet surface of gel barrier with higher resistance than that formed in acidic medium. However, the dissolution of these tablets in the simulated intestinal fluid was faster as a result of disintegration effect of chitosan. This disintegration effect of chitosan might be explainable by its insolubility in neutral medium.