Pharmacologic effect of imipramine, paroxetine, and sertraline on 35% carbon dioxide hypersensitivity in panic patients: A double-blind, random, placebo-controlled study

The effects of short treatment (7 days) with the tricyclic antidepressant imipramine and the two selective serotonin reuptake inhibitors paroxetine and sertraline on the reactivity to inhalation of 35% CO2/65% O2 were compared in 70 panic patients who had positive responses to 35% CO2 inhalations. A double-blind, random, placebo-controlled design was applied. Each patient was given the 35% CO2 challenge on days 0 (before starting the treatment), 3, and 7. In the placebo group, there were no significant changes in the reactivity to 35% CO2 in the three sessions whereas there were significant similar reductions of reactivity to 35% CO2 in all three drug-treated groups. These results confirm the good reproducibility of 35% CO2 reactivity and the negligible effects of placebo on reactivity to CO2 and suggest that short treatments with imipramine, paroxetine, and sertraline decrease reactivity to 35% CO2, possibly as an expression of their antipanic properties.