Abstract
Purpose :
The objective of the study is to evaluate the safety of PHMB 0.08% following repeated ocular instillation for 26 weeks in rabbits.
Methods :
Eight male and eight female New Zealand White rabbits were treated into the right eye with 1 drop of PHMB 0.08%: 16 times/day at approximately 1 hour-intervals from day 1 to day 5; 8 times/day at approximately 2-hour intervals from day 6 to week 3 (day 21) and 4 times/day at approximately 4-hour intervals from week 4 to week 26. Another identical group of animals, acting as a control, was similarly treated with placebo. The left eye in both the two groups remained untreated.
Ocular irritation assessment was performed daily, before first dosing, in all animals for 28 days then weekly up to the end of the study. Slit-lamp examination and corneal epithelium fluorescein staining of both eyes of all animals were performed prior to allocation and on day 1 before the first treatment. Subsequently, all animals were examined weekly prior to the first dosing. In addition, main target tissues of all animals sacrificed at the end of the 26 weeks were histologically examined.
Results :
No irritation of the conjunctivae, iris or cornea was observed on any day of treatment in all animals treated with placebo. In the animals treated with PHMB 0.08%, slight conjunctival redness was generally noted in the majority of animals starting from day 2 up to day 4. Slight conjunctival chemosis was noted on day 2 and 3 in a few numbers of treated animals as well as slight discharge in few animals on the first days of the treatment period. Afterwards, in the eye treated with PHMB 0.08% slight conjunctival redness and discharge were observed only in a sporadic number of animals during the study. No lesions were observed with fluorescein staining examination in all animals treated with PHMB 0.08% or with placebo. No ocular abnormalities were detected throughout the study with slit-lamp examination. No treatment-related changes were reported after histopathological examination of the eyes and their annexa as well as in the remaining organs/tissues.
Conclusions :
A 26-week repeated instillation of PHMB 0.08% in rabbits did not show any relevant treatment-related effect. These favourable results strengthen our plan to develop PHMB 0.08% ophthalmic solution as a novel orphan drug for the treatment of Acanthamoeba keratitis.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.