Carbon dioxide test as an additional clinical measure of treatment response in panic disorder.
OBJECTIVE
We aim to determine if a treatment with a dose of clonazepam--2 mg/day, for 6 weeks, blocks spontaneous panic attacks and the ones induced by the inhalation of 35% carbon dioxide (CO2) in panic disorder (PD) patients. The CO2 challenge-test may be a useful addition tool for measuring the pharmacological response during the initial phase (6 weeks) in the treatment of PD.


METHODS
Eighteen PD patients drug free for a week participated in a carbon dioxide challenge test. Fourteen had a panic attack and were openly treated for a 6-week period with clonazepam. At the end of the 6-week period they were submitted again to the CO2 challenge test.


RESULTS
After 6 weeks of treatment with clonazepam, 12 of 14 PD patients (85.7%) did not have a panic attack after the CO2 challenge test. Just 2 of 14 patients (14.3%) had a panic attack after the CO2 challenge test. Ten of 14 (71.4%) PD patients had panic free status after clonazepam treatment. The 2 patients who had a panic attack in the sixth week, after the CO2 test, did not have panic free status after the treatment with clonazepam.


CONCLUSIONS
The CO2-test may be a valid tool for testing and predicting the drug response.
Laboratory of Panic & Respiration, Institute of Psychiatry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil. alnardi@novant.com.br
Alexandre M
AM
Valença
Antonio Egidio
AE
Nardi
Isabella
I
Nascimento
Walter A
WA
Zin
Márcio
M
Versiani
D000280:Administration, Inhalation; D000293:Adolescent; D000328:Adult; D000927:Anticonvulsants / Q000627:therapeutic use*; D001569:Benzodiazepines / Q000627:therapeutic use; D001944:Breath Tests / Q000379:methods; D002245:Carbon Dioxide / Q000009:adverse effects; D002998:Clonazepam / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016584:Panic Disorder / Q000139:chemically induced / Q000175:diagnosis / Q000188:drug therapy*; D016896:Treatment Outcome
D000927:Anticonvulsants; D001569:Benzodiazepines; D002245:Carbon Dioxide; D002998:Clonazepam