An evaluation of the irritancy potential of povidone iodine solutions: comparison of subjective and objective...

A double-blind study has been carried out in 12 normal volunteer subjects in order to determine the relative irritancy of povidone-iodine solutions. Aqueous solutions of 10% povidone-iodine (PI), standardized 10% povidone-iodine (SPI) and reformulated standardized 10% povidone-iodine (RSPI) were applied to the backs and occluded using aluminium chambers. At 1, 2, 3, 4, 5, 6, and 8 hours, chambers were removed and the degree of cutaneous irritancy assessed. As well as subjective assessment of erythema, objective measurement of skin colour was performed using an erythema meter. In addition, laser Doppler blood-flow measurements have been carried out. The results show a rapid increase in cutaneous irritancy as evidenced by an increase in visual scores of erythema, increased erythema meter readings and increased cutaneous blood-flow. The increase was greatest for SPI treated sites for all three methods. Statistically these differences were significant at P < 0.05. Thus in this controlled study it has been possible to discriminate between the similar formulations in terms of their cutaneous irritancy.