Neuropsychological dose effects of a freon, trifluoromethane (FC-23), compared to N2O

A. A. Rahill, G. G. Brown, S. C. Fagan, J. R. Ewing, C. A. Branch, G. Balakrishnan

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Animal studies show FC-23 to be a promising magnetic resonance imaging indicator of regional cerebral blood flow. In a Phase 1, dose ranging (investigative new drug) study, neuropsychological (NP) tests, subjective ratings, and intensive physiological monitoring were used to determine the maximum tolerated concentration of FC-23 for human application. Five normal healthy male volunteers were exposed to concentrations of FC-23 between 10% and 60% [randomly interleaved with exposures to both room air and 40% nitrous oxide (N2O)] in a within-subjects, double-blind design. Analyses of individual cases and ranked group data showed that individuals tolerated the 30% concentration of FC-23 according to established criteria. Planned comparisons indicated that inhalation of FC-23 produced smaller NP changes and fewer negative symptoms than 40% N2O but poorer NP performance and more negative symptoms than room air. This study indicated that FC-23 is not inert and that humans do not tolerate concentrations suitable for current MRI technology. NP and subjective data assisted in characterizing the sedative effect of FC-23. Copyright (C) 1998 Elsevier Science Inc.

Original languageEnglish (US)
Pages (from-to)617-626
Number of pages10
JournalNeurotoxicology and Teratology
Issue number6
StatePublished - Nov 1998
Externally publishedYes


  • Computer-assisted tests
  • Freon
  • Neuropsychological tests
  • Nitrous oxide
  • Subjective effects
  • Trifluoromethane

ASJC Scopus subject areas

  • Toxicology
  • Developmental Neuroscience
  • Cellular and Molecular Neuroscience


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