Ex vivo evaluation of the stability, safety and antibacterial efficacy of an extemporaneous povidone-iodine preparation for ophthalmic applications.

BACKGROUND: Povidone-iodine is used as a cost-effective broad-spectrum antiseptic in the prophylaxis and treatment of certain ocular infections. In this study, the stability, ophthalmic irritation potential and antibacterial efficacy of an extemporaneous povidone-iodine preparation was determined using established ex vivo and in vitro assays. METHODS: Extemporaneous iodine was prepared by simple dilution in normal saline. Preparation stability was evaluated by monitoring concentration and pH. Ocular safety was determined using the bovine cornea opacity and permeability assay. Efficacy was assessed by determining the minimum inhibitory and minimum bactericidal concentration of the preparation on Staphylococcus aureus and Pseudomonas aeruginosa. RESULTS: Diluted povidone-iodine maintained its stability over the 28-day evaluation. The formulation caused mild ocular irritation at the lowest prepared concentration (0.5 per cent w/v), with irritation noticeably increased at higher concentrations. The preparation showed minimum bactericidal and inhibitory concentrations of 0.078 and 0.3 per cent w/v on S. aureus and P. aeruginosa, respectively. CONCLUSIONS: This study confirms the stability and broad-spectrum antibacterial efficacy of povidone-iodine, while addressing the ocular irritation potential of this chemical.

Preclinical studies evaluating the effect of semifluorinated alkanes on ocular surface and tear fluid dynamics.

PURPOSE: Dry eye disease (DED) is one of the most prevalent ocular surface disorders that presents clinically. Recently, the semifluorinated alkane (SFA) perfluorohexyloctane (NovaTears®; EvoTears®) entered the market for the management of evaporative DED, while perfluorobutylpentane has been used as a vehicle to enhance ocular drug delivery. This study evaluated the mechanisms by which SFAs might improve therapeutic outcomes in DED. METHODS: Interactions of both SFAs with the corneal surface were evaluated ex vivo using high-speed photography. The in vivo influence of SFAs on tear fluid dynamics was evaluated in healthy rabbit eyes observing changes in lipid layer grade, tear evaporation rate, tear volume and tear osmolarity. Furthermore, ocular tolerability was confirmed by clinical scoring and sodium fluorescein staining. RESULTS: Ex vivo studies demonstrated that both SFAs rapidly spread on the ocular surface with their contact angle on the cornea being virtually zero. A significant improvement in lipid layer grade was observed immediately after instillation of both SFAs in vivo, although the improvement was more sustained upon instillation of perfluorohexyloctane with a statistically significant difference compared to saline instillation evident from day five onwards. No significant changes in tear evaporation rate, volume or osmolarity, nor any signs of ocular irritation were observed after application of either SFA over the seven-day study period. CONCLUSION: Both SFAs showed excellent spreading on the ocular surface. Perfluorohexyloctane improved the lipid layer grade significantly after topical application supporting its potential to stabilise the tear film lipid layer and thus provide symptomatic relief in evaporative DED.