Peer-reviewed veterinary case report
Oxytetracycline levels in dog tears after eye ointment use
By Sigmund, Alex B et al.·Published in Veterinary ophthalmology·2020·College of Veterinary Medicine·View original on PubMed →
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Original publication title: Tear film concentrations of topically applied 0.5% oxytetracycline ointment in normal canine eyes.
- Species:
- dog
Plain-English summary
Ten healthy beagles had a special eye ointment called Terramycin (which contains oxytetracycline) applied to one eye to see how much of the medication ended up in their tears over time. The researchers found that the concentration of the medication in the tears decreased steadily over 12 hours. The ointment was effective in reaching levels higher than what is needed to fight common eye infections for several hours after application. However, the levels needed to prevent certain types of eye damage were not reached with the standard dosing.
People also search for: dog eye infection treatment · Terramycin for dogs · how long does eye ointment last in tears
Abstract
OBJECTIVE: To determine the tear film levels of oxytetracycline in normal canine eyes after application of the ophthalmic ointment, Terramycin™ (0.5% oxytetracycline, polymyxin B sulfate), to guide appropriate treatment frequency. ANIMALS STUDIED: Ten research beagles. PROCEDURES: Ten research beagles with confirmed normal eyes were administered 0.02 mL of Terramycin™ ophthalmic ointment onto the dorsal bulbar conjunctival surface of the right eye. Tear samples were collected via dye-less Schirmer tear strips at 2, 4, 6, 8, and 12 hours post-administration. The sample for each timepoint was collected on a separate day, and concentrations of oxytetracycline were determined using high-performance liquid chromatography (HPLC). RESULTS: There was a semi-logarithmic decline in the median tear concentration of oxytetracycline. The median (2.5th and 97.5th percentiles) tear concentrations of oxytetracycline at 2, 4, 6, 8, and 12 hours were 43.5 μg/mL (11.1-302.2 μg/mL), 28.7 μg/mL (8.04-113.7 μg/mL), 16.1 μg/mL (4.96-37.7 μg/mL), 9.2 μg/mL (4.52-28.1 μg/mL), and 6.11 μg/mL (4.36-26.7 μg/mL), respectively. Mean (±SD) drug recovery via HPLC was 88% (±7.5%). CONCLUSIONS: Ophthalmic Terramycin™ achieves a substantially higher tear level than the MIC for common bacterial corneal pathogens up to 12 hours post-administration in normal eyes. Anti-collagenolytic tear levels were not achieved at the timepoints evaluated or with the manufacturer-prescribed dosing frequency. HPLC can be used to analyze tear concentrations of ophthalmic ointment formulations.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/32524758/