Neuropsychological dose effects of a freon, trifluoromethane (FC-23), compared to N2O.
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.
Rahill
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AA
Department of Neurology, Henry Ford Hospital, Detroit, MI, USA. alicea@envmed.rochester.edu
Brown
G G
GG
Fagan
S C
SC
Ewing
J R
JR
Branch
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CA
Balakrishnan
G
G
D000328:Adult; D000339:Affect / Q000187:drug effects*; D005617:Chlorofluorocarbons, Methane / Q000494:pharmacology*; D003071:Cognition / Q000187:drug effects*; D003287:Contrast Media / Q000494:pharmacology; D004311:Double-Blind Method; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009483:Neuropsychological Tests; D009609:Nitrous Oxide / Q000494:pharmacology*; D011597:Psychomotor Performance / Q000187:drug effects*
D005617:Chlorofluorocarbons, Methane; D003287:Contrast Media; D009609:Nitrous Oxide; C009554:fluoroform