Brinzolamide–loaded nanoemulsions: ex vivo transcorneal permeation, cell viability and ocular irritation tests

Abstract

The aim of this study was to investigate the corneal penetration of brinzolamide (BZ) nanoemulsions (NEs) and evaluate their in vitro and ex vivo irritancy potential. Twelve BZ NEs were prepared by the spontaneous emulsification method and ex vivo permeability studies were conducted using excised bovine corneas fixed onto Franz diffusion cells. To confirm the safety of the formulations for ophthalmic use, preparations were examined for potential ocular irritancy using a cell viability assay on retinal cells, the Hen's Egg Test-Chorio-Allantoic Membrane (HET-CAM) and the bovine corneal opacity-permeability (BCOP) test. Seven BZ NEs exhibited superior penetration across isolated bovine cornea compared to the marketed BZ suspension. The half maximal inhibitory concentration (IC₅₀) values of various surfactants and oils determined using the sulforhodamine B cell viability assay on retinal cells showed that Transcutol P, Cremophor RH40 and Triacetin were the least toxic excipients and may be safely used in the eye at various concentrations. HET-CAM and BCOP tests revealed that NE6B and NE4C did not result in any irritation and were thus considered safe for ocular use. Our finding suggests that optimized NEs can be a safe and effective vehicle for ocular delivery of BZ.

Keywords:

• Brinzolamide
• glaucoma
• nanoemulsions
• transcorneal permeation
• cell viability assay
• ocular irritancy test

Acknowledgements

We thank the Research Deputy of Shahid Beheshti University of Medical Sciences as well as the School of Pharmacy and the Department of Ophthalmology at the University of Auckland for supporting this work.

Disclosure statement

The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript.