Enhancing Activity of Non-Antibiotic Antimicrobial Agents

ENHANCING ACTIVITY

Mention has already been made of the use of permeabilizing chelators to enhance the penetration of biocides to their target. Much effort has also been expended in the search for synergistic combinations of biocides which, when added together, will greatly amplify the bactericidal effect. While theoretically possible, and potentially predictable from mechanism of action studies, in practice this effect is elusive; combinations of phenylmercuric acetate with benzalkonium chloride, lipophilic weak acids with fatty alcohols, and chlorocresol with phenylethanol have been reported. The most likely route to enhancing activity lies with optimizing biocide formulations to ensure maximum availability of the active moiety—particularly important in situations of pHdependency or poor water solubility. In the area of pharmaceutical and cosmetic preservation, constructive use of formulation ingredients, each with some intrinsic antimicrobial activity, has successfully built on the activity of the original preservative agent to create a cumulative bactericidal effect, an approach called ‘hurdle technology’.