Back to Search Start Over

Molecular iodine is not responsible for cytotoxicity in iodophors.

Authors :
Freeman C
Duan E
Kessler J
Source :
The Journal of hospital infection [J Hosp Infect] 2022 Apr; Vol. 122, pp. 194-202. Date of Electronic Publication: 2022 Feb 04.
Publication Year :
2022

Abstract

Background: Ten percent povidone-iodine (PVP-I) was initially promoted as 'tamed iodine' as the chemical activity of the active biocide, uncomplexed or free molecular iodine (I <subscript>2</subscript> ), is reduced 30- to 50-fold compared with Lugol's solution. The idea that I <subscript>2</subscript> is responsible for topical iodine staining and irritation remains widely held. However, there are no controlled studies that characterize the cytotoxicity and staining of the hydrophobic I <subscript>2</subscript> species compared with the other hydrophilic iodine species that comprise over 99.9% of the total iodine in topical iodine disinfectants.<br />Aims: To compare the staining properties of the I <subscript>2</subscript> species with other topical iodine disinfectants; to evaluate if the concentrations of I <subscript>2</subscript> in diluted PVP-I used to reduce severe acute respiratory syndrome coronavirus-2 in the nasal cavity are potentially cytotoxic; and to determine if high concentrations of I <subscript>2</subscript> can be delivered beyond the stratum corneum into the hypodermis, which could provide a mechanistic rationale for I <subscript>2</subscript> out-gassing.<br />Methods: Five liquid compositions that contained complexed and uncomplexed (free) I <subscript>2</subscript> in aqueous and non-aqueous carriers were used to evaluate the interaction of I <subscript>2</subscript> with mammalian cells in culture as well as human and pig skin.<br />Findings: Concentrations of I <subscript>2</subscript> (7800 ppm) that are 1500 times higher than that found in PVP-I can be applied to skin without irritation and staining. I <subscript>2</subscript> is not cytotoxic at concentrations >100 times higher than that found in PVP-I, and does not contribute materially to staining of skin at concentrations found in Lugol's solution (approximately 170 ppm). I <subscript>2</subscript> can partition into hypodermis tissue, remain there for hours and out-gas from skin. PVP-I and Lugol's solution are highly effective topical disinfectants, but do not facilitate diffusion of I <subscript>2</subscript> through the stratum corneum.<br />Conclusion: The maximum concentration of I <subscript>2</subscript> found in diluted PVP, approximately 25 ppm, is not cytotoxic or irritating. The potential clinical utility of I <subscript>2</subscript> has been limited by incorporating this broad-spectrum biocide into acidic aqueous formulations that contain numerous chemical species that contribute toxicity but not biocidal activity. I <subscript>2</subscript> can be delivered topically into hypodermis tissue without irritation.<br /> (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Details

Language :
English
ISSN :
1532-2939
Volume :
122
Database :
MEDLINE
Journal :
The Journal of hospital infection
Publication Type :
Academic Journal
Accession number :
35124143
Full Text :
https://doi.org/10.1016/j.jhin.2022.01.015