Purpose: The purpose of this investigation was to determine the influence on the antimicrobial activity of cetylpyridinium chloride of the various components of the formulation of each of six candy based lozenges.
Methods: In vivo activity was investigated using six volunteers by determining the reduction in colony forming units recoverable from the oropharynx after sucking each lozenge separately on different days. In vitro determinations investigated the relative activity of aqueous solutions of the lozenges, the effect on activity of additional active ingredients, pH and lozenge base ingredients against separate inocula of each of the test organisms Staphylococcus aureus, Streptococcus pyogenes and Candida albicans.
Results: Both in vivo and in vitro results showed that the pH of the dissolved lozenge solution was the single most influential readily adjustable formulation parameter which significantly influenced the activity of cetylpyridinium chloride activity in candy based lozenges.
Conclusions: Lozenges containing cetylpyridinium chloride as the active ingredient should be formulated at a pH greater than 5.5.