PHARMACOLOGICAL EFFECT OF TOLOXATONE ON REACTIVITY TO THE 35-PERCENT CARBON-DIOXIDE CHALLENGE - A SINGLE-BLIND, RANDOM, PLACEBO-CONTROLLED STUDY

The effect of a short treatment (7 days) with the reversible monoamine oxidase type A inhibitor toloxatone on the reactivity to the inhalati on of 35% CO2 was evaluated in 18 panic patients who responded to 35% CO2 inhalation with panic before treatment. A single-blind, placebo-co ntrolled design was applied. Panic patients were randomly assigned to the toloxatone (N = 10) or placebo (N = 8) groups and were given the 3 5% CO2 challenge on days 1 (before starting the treatment), 3, and 7. Patients on placebo did not report any significant changes in their re activity to 35% CO2 during the three sessions, whereas patients on tol oxatone reported a significant attenuation of the reactivity on day 7. These results indicate that (1) anxiety provoked by the inhalation of 35% CO2 is reproducible; (2) placebo has a negligible effect on 35% C O2 reactivity; and (3) reactivity to 35% CO2 is significantly attenuat ed by short treatment with toloxatone, possibly related to its antipan ic activity.