Modification of 35% carbon dioxide hypersensitivity across one week of treatment with clomipramine and fluvoxamine: A double-blind, randomized, placebo-controlled study

The effects of short treatments (7 days) with clomipramine and fluvoxamine on the reactivity to inhalations of 35% CO₂/65% O₂ were compared in 39 panic patients who had positive responses to 35% CO₂ inhalations. A double-blind, randomized, placebo-controlled design was applied. Each patient was given the 35% CO₂ challenge on days 0 (before starting treatment), 3, and 7. Patients on placebo did not report any significant changes in their reactivity to 35% CO₂ across the three sessions, whereas patients on clomipramine and fluvoxamine reported a significant attenuation of the reactivity on day 7. These results indicate that treatments with clomipramine and fluvoxamine decrease hypersensitivity to 35% CO₂ after a few days, suggesting a relevant role of the modulation of CO₂ sensitivity by the serotonergic system in antipanic properties of these compounds.