Natural product-based excipients for topical green formulations

Abstract

The industry has been paying more attention to the quality of excipients since they play a fundamental role in the efficacy, safety, and acceptability of pharmaceutical products. However, in the case of topical products synthetic compounds have been a concern for consumers, since they can lead to sensitization reactions, disturbance of the microbiota, and impairment in the skin barrier function. Consequently, the pharmaceutical industry has been looking for safer, cheaper, more effective, and more eco-friendly alternatives, and so natural raw materials (or natural ingredients) are good candidates to meet this demand. This narrative review aims to present studies that use natural excipients and describe their advantages, disadvantages and overall performance. In topical formulations, natural ingredients can be found in the form of emulsifiers, emollients, preservatives, gelling agents, humectants, and permeation enhancers. The studies show that they fulfill their role in formulations, demonstrating rheological and stable characteristics, as well as not being toxic to skin cells and the microbiota. Moreover, many natural raw materials are biodegradable, being less harmful to the environment. More studies are still needed to effectively replace synthetic excipients with natural ones, while maintaining quality control. These raw materials present themselves as a potential alternative and there are vast resources still little explored, and those already used are highly effective and safe.