One-Year Study in Dogs of the Toxicity of HFA-134a by Inhalation

AbstractHFA-134a, a chlorine-free hydrofluoroalkane, was administered for 1 h daily to beagle dogs by means of a system for inhalation by face mask. In this 1-yr study, animals received atmospheric air, air containing an additional 12% nitrogen, or air containing a nominal 12% HFA-134a for 376 or 377 days. HFA-134a was rapidly absorbed into and cleared from the blood. There were no treatment-related clinical signs or effects on body weight, food consumption, ophthalmoscopy, heart function, respiratory rate, pulse rate, haematology, blood biochemistry, urine analysis, or postmortem findings. HFA-134a was considered to be nontoxic and to provide a safe alternative to chlorofluorocarbons for use in pharmaceutical metered-dose inhaler formulations.