Fate of chlorbutol during storage in polyethylene dropper containers and simulated patient use

The disappearance of chlorbutol from aqueous solutions stored in polyethylene containers under various experimental and simulated patient use conditions is described. Chlorbutol is lost by sorption into the container wall, container insert and by permeation into the external environment. The extent of chlorbutol loss from solution and uptake by the container components is dependent on temperature, chlorbutol concentration and the closure used. Aqueous chlorbutol solutions stored in the polyethylene container evaluated have a predicted shelf-life (time for 10% loss) of about 4 months at 25 degrees C and 8 months at 20 degrees C. Negligible loss is found during simulated patient use over 1 month.