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Effect of norfloxacin and clonidine on human trabecular meshwork cells in vitro
1Department of Ophthalmology, Union Hospital, Tongji Medical University, Wuhan, People's Republic of China.
Abstract:
We evaluated the effect of norfloxacin and clonidine on the morphology, DNA synthesis and phagocytic activity of cultured human trabecular meshwork cells in the 3rd-5th generations. Exposure to norfloxacin at a concentration of 1.5 x 10(-4) g ml-1 for 6 h led to retraction of cytoplasmic processes and rounding of cell profile, and exposure for 48 h caused cell death. Exposure to clonidine at 1.0 x 10(-3) g ml-1 for 12 h caused cell degeneration, and exposure for 72 h led to cell death. The morphologic changes were dose-time dependent. Tritiated thymidine incorporation was determined as an index of DNA synthesis, which was significantly inhibited by 1.5 x 10(-5) g ml-1 norfloxacin or 1.0 x 10(-3) g ml-1 clonidine, but obviously enhanced by 1.0 x 10(-4) and 1.0 x 10(-5) g ml-1 clonidine. Both drugs inhibited phagocytosis of latex microspheres in a dose-dependent mode. According to the presented results and the pharmacokinetic data reported in the literature, we suggest that the topical use of norfloxacin should not be too frequent or continued too long, especially when the corneal epithelium was not intact; clonidine has no deleterious effect on trabecular cells in its conventional use.
Insights
Norfloxacin can harm human trabecular meshwork cells with prolonged use, especially on damaged corneas. Clonidine, however, appears safe for trabecular cells during conventional use.
Area of Science:
- Ophthalmology
- Cell Biology
- Pharmacology
Background:
- Trabecular meshwork cells are crucial for maintaining intraocular pressure.
- Understanding the ocular surface toxicity of commonly used medications is vital.
Purpose of the Study:
- To investigate the effects of norfloxacin and clonidine on human trabecular meshwork (HTM) cells.
- To assess the impact on cell morphology, DNA synthesis, and phagocytic activity.
Main Methods:
- Primary human trabecular meshwork cells (3rd-5th generations) were cultured.
- Cells were exposed to varying concentrations and durations of norfloxacin and clonidine.
- Morphological changes, DNA synthesis (via tritiated thymidine incorporation), and phagocytosis of latex microspheres were evaluated.
Main Results:
- Norfloxacin induced cell retraction, rounding, and death in a dose- and time-dependent manner.
- Clonidine caused cell degeneration and death at higher concentrations and longer exposures.
- Both drugs inhibited phagocytic activity.
- DNA synthesis was inhibited by norfloxacin and high-dose clonidine, but enhanced by lower clonidine concentrations.
Conclusions:
- Topical norfloxacin use should be limited in duration and frequency, particularly with compromised corneal epithelium.
- Conventional use of clonidine does not appear to have deleterious effects on trabecular meshwork cells.