Effects of dehydration on corneal tissue absorption of topical azithromycin in rabbits

Purpose: To assess the corneal tissue absorption of azithromycin in desiccated and normal eyes of rabbits. Methods: A total of 25 New Zealand Albino rabbits weighing 2-3 kg each were included. One eye of each rabbit was desiccated. The other eye was left as control. Azithromycin 1.5% topical eyedrops were instilled in both eyes. Five rabbits were sacrificed at each of the following time points: 30 min, 3 hr, 6 hr, and 12 hr. Corneal tissues specimens were subjected to high-performance liquid chromatography mass spectrometry. A paired t test was used to evaluate the statistical difference in corneal tissue absorptions of azithromycin at each time point. Results: The mean corneal tissue levels of azithromycin in dry eyes were 66.3 μg/ml, 92.6 μg/ml, 117.5 μg/ml, and 179.9 μg/ml, and the mean corneal tissue levels of azithromycin in normal eyes were 42.0 μg/ml, 43.4 μg/ml, 43.3 μg/ml, and 80.0 μg/ml at 30 min, 3 hr, 6 hr, and 12 hr respectively. Both groups showed increase in corneal tissue absorption overtime (p <0.0001). Significantly higher levels of azithromycin were noted in dry eyes at each time point except at the 30-min time point. Conclusions: This study demonstrated that corneas exposed to desiccation showed statistically significant increase in azithromycin level compared to normal eyes.