Intraocular Pharmacokinetics of Povidone‐iodine and the Effect of Repeat Injection with low concentration on the Experimental S. epidermidis Endophthalmitis

Abstract

PurposeTo investigate the safety and a half‐life of intravitreal povidone‐iodine (PVI) and the efficacy of single and repeat PVI injection in experimental S. epidermidis endophthalmitis.MethodsIn Phase I study, the pharmacokinetics and the safety of PVI were investigated. Forty New Zealand White rabbits receiving intravitreal 0.1% and 0.3% PVI were divided into Group I and II. The pharmacokinetics of PVI was analyzed using high performance liquid chromatography (HPLC). To confirm the safety of intravitreal PVI, electroretinography (ERG) and histologic examination were conducted at baseline, 6 and 12 hours. In Phase II study, the efficacy of PVI for the treatment of S. epidermidis endophthalmitis was evaluated in 4 groups (n = 10 in each group). After the induction of S. epidermidis endophthalmitis, 0.1% and 0.3% PVI were injected once in Group A and B, and three times every second day in Group C and D respectively. The fellow eyes receiving sham injection were the control. ERG, histologic examination and vitreous culture for S. epidermidis were conducted at day 14.ResultsIn Phase I, 0.1% and 0.3% PVI groups did not show notable retinal damage in ERG and histologic findings and half‐life in vitro was 3.27 and 3.58 hours, respectively. In Phase II, all Groups showed a significant improvement of endophthalmitis, compared to the controls. However, four eyes in Group A and 3 eyes in Group B demonstrated a bacterial growth in vitreous at day 14, but none in Group C and D. In the histologic findings, retinal damage was detected as lymphocyte infiltration in the inner retinal layers of eyes with bacterial growth.Conclusions0.1% and 0.3% PVI can be tolerated in rabbit eyes. Half‐life of the PVI was about 3 hours in vitreous. Repeat PVI injection with low concentration is likely to be effective and safe for the treatment of S. epidermidis endophthalmitis.