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Effects of timolol on bovine corneal endothelial cultures
Abstract:
The chronic use of timolol (Timoptic) maleate to control glaucoma may produce cytotoxic complications in the cornea. We have therefore compared the relative toxic effects of the commercial ophthalmic preparation with that of the pure compound. Commercial vehicle, either with or without 16 mM timolol maleate, killed cultures within the first five minutes of exposure. Pure timolol maleate, however, caused rapid but reversible cellular contractions, and cells remained viable in it for over 24 hours. Dilution with culture medium reduced both the cytotoxicity and the speed of the contractions. Incubation in 1:100 dilutions of vehicle or commercial drug preparations or in 0.16 mM pure timolol maleate did not alter cellular morphology. The results indicate that while undiluted vehicle is toxic, timolol maleate is not.
Insights
Timolol maleate, used for glaucoma, may cause eye irritation. However, pure timolol maleate is not toxic to corneal cells, unlike the commercial preparation's vehicle.
Area of Science:
- Ophthalmology
- Cell Biology
- Pharmacology
Background:
- Glaucoma treatment often involves chronic use of timolol maleate eye drops.
- Potential cytotoxic effects of ophthalmic preparations on the cornea are a concern.
Purpose of the Study:
- To compare the toxicity of commercial timolol maleate ophthalmic preparations with the pure compound.
- To assess the impact of the vehicle and timolol maleate on corneal cell viability and morphology.
Main Methods:
- In vitro cell culture experiments were performed.
- Corneal cells were exposed to commercial vehicle, pure timolol maleate, and various dilutions.
- Cellular viability, contraction, and morphology were observed over time.
Main Results:
- The commercial vehicle, with or without timolol maleate, was cytotoxic within minutes.
- Pure timolol maleate induced rapid but reversible cell contractions, with cells remaining viable for over 24 hours.
- Dilutions of the commercial preparation and lower concentrations of pure timolol maleate did not cause significant cellular damage.
Conclusions:
- The vehicle in commercial timolol maleate preparations exhibits significant cytotoxicity.
- Pure timolol maleate demonstrates low toxicity to corneal cells.
- The observed toxicity is primarily attributed to the commercial vehicle, not the active drug ingredient.