The efficacy of many useful drugs can be improved by carrying out certain pharmaceutical manipulations in delivery route e.g. by transdermal drug delivery system. However, excellent impervious nature of stratum corneum restricts both the type and number of drugs that can be delivered to the systemic circulation by this route. A popular approach for increasing the percutaneous permeation of drug is to incorporate penetration enhancers into the formulations. The use of synthetic chemical enhancers for enhancing the percutaneous permeation of drugs is decreasing due to their long term effects and potential systemic toxicity. Hence, the main objective of this study was to evaluate the influence of triterpene and steroidal saponins on percutaneous permeation of carvedilol and to understand the mechanism(s) responsible for this effect.

Chitosan is the deacetylated form of chitin. Generally, the substance becomes soluble in dilute acids when the degree of deacetylation is more than 50%. The solubility of chitosan in dilute acids is often needed to be modified when specific drug release properties have to be tailored into the dosage form. The available toxicological data on chitosan and its modified forms appears to indicate its safety for oral use because high doses have been found to be tolerated well in rodents and rabbits. However, its local action as a haemostatic together with its ability to activate macrophages and cause cytokine release may require a careful assessment of its safety for parenteral use. This book offers the dynamics of chitosan's detailed composition.