title: Zinc oxide as a new antimicrobial preservative of topical products: interactions with common formulation ingredients.
abstract: Zinc oxide (ZnO) appears as a promising preservative for pharmaceutical or cosmetic formulations. The other ingredients of the formulations may have specific interactions with ZnO that alter its antimicrobial properties. The influence of common formulation excipients on the antimicrobial efficacy of ZnO has been investigated in simple model systems and in typical topical products containing a complex formulation. A wide variety of formulation excipients have been investigated for their interactions with ZnO: antioxidants, chelating agents, electrolytes, titanium dioxide pigment. The antimicrobial activity of ZnO against Escherichia coli was partially inhibited by NaCl and MgSO4 salts. A synergistic influence of uncoated titanium dioxide has been observed. The interference effects of antioxidants and chelating agents were quite specific. The interactions of these substances with ZnO particles and with the soluble species released by ZnO were discussed so as to reach scientific guidelines for the choice of the ingredients. The preservative efficacy of ZnO was assessed by challenge testing in three different formulations: an oil-in-water emulsion; a water-in-oil emulsion and a dry powder. The addition of ZnO in complex formulations significantly improved the microbiological quality of the products, in spite of the presence of other ingredients that modulate the antimicrobial activity.
authors.affiliation: Strand Cosmetics Europe, 124 route du Charpenay, 69210 Lentilly, France; Laboratoire d'Automatique et de Génie des Procédés (LAGEP) CNRS UMR5007, Université de Lyon, Université Lyon 1, Villeurbanne, F-69622 Lyon, France.
authors.forename: Julia
authors.initials: J
authors.lastname: Pasquet
authors.affiliation: Laboratoire d'Automatique et de Génie des Procédés (LAGEP) CNRS UMR5007, Université de Lyon, Université Lyon 1, Villeurbanne, F-69622 Lyon, France. Electronic address: chevalier@lagep.univ-lyon1.fr.
authors.forename: Yves
authors.initials: Y
authors.lastname: Chevalier
authors.affiliation: Strand Cosmetics Europe, 124 route du Charpenay, 69210 Lentilly, France.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Couval
authors.affiliation: Strand Cosmetics Europe, 124 route du Charpenay, 69210 Lentilly, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Bouvier
authors.affiliation: Laboratoire d'Automatique et de Génie des Procédés (LAGEP) CNRS UMR5007, Université de Lyon, Université Lyon 1, Villeurbanne, F-69622 Lyon, France. Electronic address: marie.bolzinger@univ-lyon1.fr.
authors.forename: Marie-Alexandrine
authors.initials: MA
authors.lastname: Bolzinger
mesh_terms: D000287:Administration, Topical; D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology; D001205:Ascorbic Acid / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D001230:Aspergillus / Q000187:drug effects / Q000254:growth & development; D002084:Butylated Hydroxytoluene / Q000737:chemistry / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects / Q000254:growth & development; D002614:Chelating Agents / Q000737:chemistry / Q000494:pharmacology; D004492:Edetic Acid / Q000737:chemistry / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D005079:Excipients / Q000737:chemistry / Q000494:pharmacology; D008278:Magnesium Sulfate / Q000737:chemistry / Q000494:pharmacology; D011310:Preservatives, Pharmaceutical / Q000737:chemistry / Q000494:pharmacology; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development; D012965:Sodium Chloride / Q000737:chemistry / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development; D014025:Titanium / Q000737:chemistry / Q000494:pharmacology; D015034:Zinc Oxide / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000890:Anti-Infective Agents; D000975:Antioxidants; D002614:Chelating Agents; D005079:Excipients; D011310:Preservatives, Pharmaceutical; C009495:titanium dioxide; D002084:Butylated Hydroxytoluene; C011669:ascorbate-2-phosphate; C065378:ascorbic acid 2-O-glucoside; D012965:Sodium Chloride; D008278:Magnesium Sulfate; D004492:Edetic Acid; D014025:Titanium; D001205:Ascorbic Acid; D015034:Zinc Oxide
keywords: Challenge tests; Excipients; Interactions; Preservative; Topical formulations; Zinc oxide