The 35% CO2 hyperreactivity and clinical symptomatology in patients with panic disorder after 1 week of treatment with citalopram: An open study

The effect of a short treatment (7 days) with citalopram on the reactivity to inhalations of 35% CO₂ and 65% oxygen and on clinical symptomatology was investigated in 15 patients with panic disorder who had a positive response to 35% CO₂ inhalation. An open study design was applied. On day 0, before starting drug treatment, and after 1 week of treatment, each patient underwent the 35% CO₂ challenge, and clinical symptomatology was evaluated with psychometric scales. The results showed a significant reduction of CO₂ reactivity and of scores on the anticipatory anxiety subscale of Panic Associated Symptoms Scale. These results confirm that the serotonergic system plays an important role in the modulation of CO₂ hyperreactivity and suggest an early anxiolytic effect of citalopram in patients who have panic disorder and are hyperreactive to CO₂.