Abstract
Abstract: :
Background: Triamcinolon depot preparations have been routinely used as intravitreal drugs to control macular edema of different origin after the removal of the solvent. Despite their broad clinical use as intraocular agents, steroids have not widely been assessed regarding their acute and chronic effects on cell culture. We therefore compared the acute and chronic toxicities of different steroids on cultured human retinal pigmented epithelial (RPE) cells using clinically–relevant concentrations and an identical experimental set–up for each agent. Methods: Monolayers of human RPE cells were incubated with various concentrations (0.1 – 10 mg/ml) of triamcinolone (0.1 – 10 mg/ml), betamethasone (0.01 – 1 mg/ml), and their solvents after overnight sedimentation or the water–soluble methyl–prednisolone (0.1 – 10 mg/ml) for 5 minutes (acute exposure) or 6 days (chronic exposure). Using the propidium iodide assay, acute cytotoxicity was monitored at 15–minute intervals for up to 3 hours. Chronic cytotoxicity was assessed by monitoring cell calcein esterase activity, cell proliferation and cell morphology (viability) after 6 days of exposure. Results: None of the depot steroids showed evident acute or chronic toxicity in the clinically used concentrations after removal of the toxic solvent by overnight sedimentation. In higher concentrations, a moderate inhibition of RPE proliferation was observed. Betamethasone and triamcinolone effects on cell proliferation and viability were comparable. Conclusions: Simple sedimentation and replacement of the supernatant by BSS may be sufficient to remove toxic compounds prior to intravitreal use and not be prone to a contamination risk by additional filtering or washing techniques. A concentration above 1 mg/ml triamcinolone or above 0.1mg/ml betamethasone interferes not only with cell proliferation, but also with cell metabolism. This should be considered prior to high dose intravitreal depot steroid treatment.
Keywords: corticosteroids • drug toxicity/drug effects • pharmacology