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
How to Cite
Arnold, T. S., Wittenburg, L. A. and Powell, C. C. (2013), Effect of topical naltrexone 0.3% on corneal sensitivity and tear parameters in normal brachycephalic dogs. Veterinary Ophthalmology. doi: 10.1111/vop.12079
- 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.