ABSTRACT
Pharmaceutical products contain number of excipients besides active principle, e.g. diluents, vehicles, antioxidants, chelating agent and preservative etc. Each excipient performs intended specific function. Antimicrobial preservatives are used to reduce the likelihood of microbial growth in pharmaceutical products. Preservatives interact specifically or non-specifically with either active or non active principles of formulation or in some cases both. In general interactions arc antagonistic in nature. However, in some cases this interaction may synergise the preservative activity or are beneficial in some other form. This review article highlights documented interactions both synergistic and antagonistic in nature between preservatives and other components of formulation. It may also help in acquiring better understanding and appreciation of implication of adding preservative to the formulation