Antipanic effect of fluoxetine measured by CO2 challenge test.

Biological Psychiatry

PubMedID: 9564447

Bocola V, Trecco MD, Fabbrini G, Paladini C, Sollecito A, Martucci N. Antipanic effect of fluoxetine measured by CO2 challenge test. Biol Psychiatry. 1998;43(8):612-5.
BACKGROUND
Respiratory symptoms are important in panic disorder for frequency and intensity. Patients with this disorder are often chronic hyperventilators, and inhalation of carbon dioxide is a strong panicogenic stimulus. We tested the hypothesis of whether respiratory parameters may be used as indicators of the course of panic disorder during its treatment with fluoxetine.

METHODS
Nine patients with panic disorders, previously shown to panic in response to intravenously administered lactate, and 10 control subjects underwent the Read rebreathing test by a 5-min inhalation of a 7% CO2/93% O2 mixture before and after 1 month of fluoxetine treatment.

RESULTS
At baseline, patients differed from controls for higher percent value of expiratory reserve volume/vital capacity ratio and ventilatory response. Eight of the 9 patients had panic in response to the CO2 challenge. After fluoxetine, respiratory parameters decreased significatively, and only 3 patients remained hypercarbic challenge responders.

CONCLUSIONS
The carbon dioxide challenge may represent a useful tool to evaluate the individual respiratory set, which may be a marker of the vulnerability to panic attack. Assessment of respiratory parameters may represent a biological marker to measure the efficacy of antipanic treatment.