April 9, 2025 – A new study from the Koret School of Veterinary Medicine at the Hebrew University of Jerusalem, led by Dr. Lionel Sebbag, has identified a more effective eyedrop formulation that improves the delivery and retention of antibiotics on the ocular surface. Published in Veterinary Ophthalmology, the study compared two commonly used excipients—PVA and XHA—as carriers for the antibiotics cefazolin and chloramphenicol in dogs.

The researchers administered eyedrops containing each antibiotic compounded in either PVA or XHA to healthy dogs and measured drug concentrations in the tear film over time. The results were striking: both antibiotics achieved significantly higher concentrations and longer retention when delivered with XHA. Notably, the overall antibiotic exposure—measured by the area under the concentration-time curve—was 2.4 times greater for cefazolin and 4.2 times greater for chloramphenicol compared to the PVA formulation.

These findings are important not only for improving the treatment of bacterial eye infections in dogs but also for their potential application to human medicine. “The findings of this study offer clear benefits for our veterinary patients, but they also carry translational relevance for human medicine,” said Dr. Sebbag. “Dogs are affected by many of the same ocular diseases as humans, and their ocular anatomy and physiology are much more comparable to human eyes than those of the more commonly used pre-clinical research species, such as rabbits or rodents. This makes dogs an especially valuable model in ophthalmic research.”

XHA’s ability to prolong antibiotic retention on the ocular surface translates into several clinical benefits: improved treatment efficacy, reduced dosing frequency, and improved compliance from pet owners and human patients alike. Importantly, maintaining therapeutic drug levels for longer periods could help minimize the risk of antimicrobial resistance, a growing global concern in both veterinary and human healthcare. Beyond its role as a drug delivery vehicle, XHA also possesses inherent antibacterial properties, supports corneal wound healing, and improves tear film quality—all of which may further boost therapeutic outcomes in patients with ocular infections.

While further studies are needed to assess clinical efficacy in dogs with active infections, this research represents a promising step forward in both veterinary ophthalmology and translational eye care. It also opens the door to exploring XHA-based delivery for other ocular medications, such as antivirals, antifungals, and anti-inflammatory agents, in both animal and human patients.

The research paper titled “Enhanced Tear Film Concentrations of Cefazolin and Chloramphenicol Using Cross-Linked Hyaluronic Acid in Canine Eyes” is now available in Veterinary Ophthalmology and is available here.

Researchers:
Dikla Arad, Ella Margot Mordechai, Yulia Goncharov, Ron Ofri, Lionel Sebbag

Institution:
Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel