Abstract
1 Groups of 60 male and 60 female B6C3F1 mice or Han- Ibm Wistar rats were exposed to HFA-134a using snout- only inhalation exposure techniques for periods of one hour daily for at least 104 weeks. HFA-134a was deliv ered directly from cylinders at vapour concentrations of 2500, 15 000 and 75 000ppm for mice and from metered-dose inhalers at vapour concentrations of 2500, 10 000 and 50 000ppm for rats.
2 Intended dosages were achieved.
3 Evidence of absorption was found at each dose level and was dose related.
4 Neither species suffered any treatment related effects on survival, clinical signs, body weights, haematology nor on the type, incidence, site or severity of gross lesions.
5 There was no effect of treatment on the type, incidence, site or severity of neoplasms in mice or rats.
6 There were no non-neoplastic findings related to treat ment in mice.
7 HFA-134a was considered not to be oncogenic and to provide a safe alternative to chlorofluorocarbons for use in pharmaceutical metered-dose inhalers.
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