Therapeutic Effects of Contact Lens with Continuous Drug Bioavailability on Rabbits

Abstract

Purpose : A novel drug-delivery lens system that provides continuous bioavailability of drug to the eye is developed. The feasibility of the system is tested by examining the therapeutic effects of timolol-maleate-loaded lens in lowering the intraocular pressure (IOP) in rabbits.

Methods : Novel silicone contact lens with drug-dissoluting inserts has been fabricated. Four New Zealand white rabbits, weighing between 2.0kg and 2.5kg, were fitted (OD) with the lenses containing embedded polyvinyl alcohol (PVA) inserts loaded with 6ul of timolol maleate (0.5% w/v ophthalmic solution). The lenses were removed and replaced periodically over the 120-hour PVA dissolution period for tonometry testing of both eyes (Icare® TONOVET, Finland). Before the lens tests, one drop of 30ul of timolol maleate (0.5% w/v ophthalmic solution) was administered on the eyes of the rabbit at the beginning of the test period. The IOPs were measured using the same procedure until IOPs were restored. Furthermore, a one-week washout period was implemented between tests.

Results : The mean IOP of the rabbits decreased from 13.1±1mmHg to 8.7±0.7mmHg within 2 to 4 hours after administering timolol eye drop. For the contact lens timolol delivery, rabbits' mean IOP dropped from 11.8±0.3mmHg to 7.7±0.2mmHg in 72 hours. Mean IOP of the rabbits rebounded to 13.3±0.6mmHg for eye drop administration and 10.0±1.8mmHg for contact lens delivery after 120 hours of monitoring.

Conclusions : The results showed that the drug was delivered continuously by the contact lens drug-delivering system with good therapeutic results. IOP in rabbits is effectively lowered by wearing a contact lens with continuous drug bioactivity. The IOP was reduced by 4mmHg when lens containing 6ul, i.e., 1/5 of standard single drop dose of 0.5% w/v ophthalmic solution were used.

This is a 2020 ARVO Annual Meeting abstract.

 

A rabbit with drug-loaded lens

 

Change in intraocular pressure in rabbits (n=4)