W. Gottardi, THE UPTAKE AND RELEASE OF MOLECULAR-IODINE BY THE SKIN - CHEMICAL ANDBACTERICIDAL EVIDENCE OF RESIDUAL EFFECTS CAUSED BY POVIDONE-IODINE PREPARATIONS, The Journal of hospital infection, 29(1), 1995, pp. 9-18
The residual effect of iodine-based disinfectants is caused by a dynam
ic back-diffusion which is the reverse of the absorption occurring dur
ing application. A very sensitive photometric method was used to measu
re the iodine flux of the back-diffusion after treating the skin with
povidone-iodine preparations and Lugol's solution. After removal of th
e preparation the intensity of the iodine flux decreases with time and
correlates with the amount of iodine being resorbed. The latter depen
ds on the concentration of free molecular iodine of the preparation, t
he contact time and the thickness of the horny layer of the treated sk
in. With Lugol's solution (approximately 170 ppm free molecular iodine
) iodine flux could be observed 12-24 h after an application of 20-60
s, while with low-level povidone-iodine preparations (0.5-20 ppm free
iodine) the measurable flux lasted only 0.5-1 h after an application t
ime of 3 min. The bactericidal activity of the back-diffusing iodine f
rom skin previously treated with a commercial povidone-iodine preparat
ion was assayed by using an inoculation with Micrococcus luteus. This
showed a logarithmic reduction of 0.4 in bacterial concentration. Sinc
e the skin was washed with soap for 1 min after application this bacte
ricidal action reflected the residual effect of the back-diffusing iod
ine.