Ocular penetration of topically applied 1% tigecycline in a rabbit model

AIM：To evaluate ocular penetration of topically applied 1% tigecycline.METHODS：Forty-two New Zealand White rabbits were divided into 3 groups. A 50 μL drop of 1% tigecycline was administered in group 1. In groups 2 and 3, the drop was administered every 15 min for 60min（keratitis protocol）. Aqueous humor samples in groups 1 and 2 were collected under general anesthesia at 15, 30, 45, 60, 120, and 180 min after the last drop. All animals in group 3 were euthanatized. Cornea, vitreous and blood samples were collected 60 and 120 min after the last drop. Tigecycline concentrations were measured using high performance liquid chromatography-mass spectrometry（LC-MS/MS）.RESULTS：The peak aqueous humor tigecycline concentration [mean 0.73±0.14 mg/L（SD） and 2.41±0.14 mg/L, respectively] occurred 45 min after topical drug application in groups 1 and 2. Group 3 mean values in the cornea, and vitreous, were 3.27±0.50 μg/g, and 0.17±0.10 mg/L at 60 min and 3.17±0.77 μg/g and 0.20±0.07 mg/L at 120 min, respectively. Tigecycline serum concentrations were negligible.CONCLUSION：Tigecycline levels in the aqueous humor in groups 1 and 2, and in the cornea in group 3 exceeded the minimum inhibitory concentrations of most grampositive organisms that cause bacterial keratitis and endophthalmitis.