Effect of topical naltrexone 0.3% on corneal sensitivity and tear parameters in normal brachycephalic dogs
Article first published online: 27 JUN 2013
© 2013 American College of Veterinary Ophthalmologists
Volume 17, Issue 5, pages 328–333, September 2014
How to Cite
Arnold, T. S., Wittenburg, L. A. and Powell, C. C. (2014), Effect of topical naltrexone 0.3% on corneal sensitivity and tear parameters in normal brachycephalic dogs. Veterinary Ophthalmology, 17: 328–333. doi: 10.1111/vop.12079
- Issue published online: 5 SEP 2014
- Article first published online: 27 JUN 2013
- Morris Animal Foundation
- corneal sensitivity;
- opioid growth factor receptor;
- opioid-like growth factor;
- tear production
To determine the effect of topical naltrexone 0.3% on tear production, corneal sensitivity, and tear film stability in normal brachycephalic dogs.
Twenty-two normal brachycephalic dogs.
Measurements of tear production (Schirmer tear test I and II), intraocular pressure (IOP), central corneal sensitivity (CS), and tear film breakup time (TFBUT) were collected at time 0, 1, and 24 h after administration of either naltrexone (NTX) 0.3% or placebo (SV). Naltrexone or SV was then administered once daily for 1 week, and the above measurements were repeated at 7 days, then again 7 days after discontinuing medication. Owners scored the degree of comfort, redness, rubbing, squinting, and tearing. Serum was collected at time 0, 1, 24 h, and 7 days to determine systemic concentrations.
Owners reported no significant change in the degree of comfort, redness, rubbing, squinting, or tearing. Naltrexone was detected in serum of all treated dogs 1-h postadministration (average: 908 pg/mL, range: 319–1570 pg/mL) and in two dogs at the 1-week time point. Naltrexone was not detected at the 24-h time point. There was no significant effect of NTX on STT1, STT2, IOP, CS, or TFBUT.
Naltrexone 0.3% is well tolerated and safe when applied topically to the eye once daily. Naltrexone 0.3% did not show any significant effects on corneal parameters as measured in this study. At once, daily dosing NTX is systemically absorbed; however, the degree of systemic absorption is not likely to be clinically significant.