Effects of alprazolam and clonidine on carbon dioxide-induced increases in anxiety ratings in healthy human subjects.
In order to investigate possible neurobiologic mechanisms underlying carbon dioxide-induced anxiety, the effects of oral alprazolam 0.75 mg and intravenous clonidine 2 mcg/kg on CO2-induced increases in ratings of subjective anxiety, pulse rate, and ventilation were measured in healthy human subjects. Pretreatment with alprazolam but not with clonidine significantly reduced the CO2-induced increase in ratings of anxiety. Neither drug altered CO2-induced increases in pulse rate or ventilatory responses. Clonidine did produce potent sedative and hypotensive effects. The behavioral data suggest that the mechanisms through which CO2 induces anxiety-like effects involve neural systems regulated by benzodiazepine receptors and, secondly, that they appear not to require normal functioning of noradrenergic systems. Carbon dioxide may provide a useful model system for identification of new drugs with anxiolytic properties.
Woods
S W
SW
Clinical Neuroscience Research Unit, Ribicoff Research Facilities, Connecticut Mental Health Center, New Haven.
Krystal
J H
JH
Heninger
G R
GR
Charney
D S
DS
D000328:Adult; D000525:Alprazolam / Q000494:pharmacology*; D001007:Anxiety / Q000139:chemically induced / Q000503:physiopathology*; D002245:Carbon Dioxide / Q000494:pharmacology; D003000:Clonidine / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D011674:Pulse / Q000187:drug effects; D012016:Reference Values; D013990:Tidal Volume
D002245:Carbon Dioxide; D003000:Clonidine; D000525:Alprazolam