Effect of moisture content, temperature and exposure time on the physical stability of chitosan powder and tablets

Context: Chitosan does not rank highly regarding its employment as tablet filler due to certain limitations. Undesirable properties that limit its utilization as excipient in solid dosage forms include its hydration propensity that negatively affects tablet stability, strength and disintegration. Objective: The objective of this study was to investigate the physical stability of chitosan powder, mixtures, granules and tablets under accelerated conditions such as elevated temperatures and humidity over different periods of time. Methods: Selected physico-chemical properties of pure chitosan powder, physical mixtures of chitosan with Kollidon (R) VA64 (BASF, Ludwigshafen, Germany), chitosan granules, as well as tablets were evaluated under conditions of elevated humidity and temperature. Results and discussion: The physical stability of chitosan tablets exhibited sensitivity towards varying exposure conditions. It was furthermore evident that the presence of moisture (sorbed water) had a marked influence on the physical stability of chitosan powder and tablets. It was evident that the presence of Kollidon (R) VA64 as well as the method of inclusion of this binder influenced the properties of chitosan tablets. The physical stability of chitosan powder deteriorated to a greater extent compared to that of the chitosan tablets, which were subjected to the same conditions. Conclusion: It is recommended that tablets containing chitosan should be stored at a temperature not exceeding 25 degrees C as well as at a relatively low humidity (<60%) to prevent deterioration of physical properties. Direct compression of chitosan granules which contained 5%w/w Kollidon (R) VA64 produced the best formulation in terms of physical stability at the different conditions.