Effects of escitalopram on anxiety and respiratory responses to carbon dioxide inhalation in subjects at high risk for panic disorder: A placebo-controlled, crossover study

Abstract

Background: Individuals with panic disorder and those at high risk for panic disorder due to a positive family history seem to have elevated sensitivities to the panicogenic effects of carbon dioxide (CO 2) inhalation as well as abnormal ventilatory responses to low doses of CO 2 exposure. Many reports have described a reduction in anxiety responses in individuals with panic disorder after a brief treatment with a variety of medications effective in the treatment of panic disorder, but few of these have used placebo control. Methods: Thirty-two unmedicated individuals who had either a past history of panic attacks or a family history of treated panic disorder and who demonstrated, at baseline, a panic attack after either a single breath of 35% CO 2 or 3 minutes of exposure to 5% CO 2 or a decline in minute volume during 3 minutes of exposure to 5% CO 2 were randomized to 2-week trials of escitalopram at 10 mg daily or placebo and, after a 1 -week washout, to a 2-week trial of the alternate condition. Results: Placebo and escitalopram conditions did not differ by changes in anxiety responses to high-dose, single-breath, or low-dose continuous-breathing CO 2 exposures. Ventilatory abnormalities were no more likely to resolve with escitalopram than with placebo. Self-ratings of anxiety and depressive symptoms showed little change over time with either escitalopram or placebo. Conclusions: Escitalopram did not produce greater changes than placebo in panic responses or in ventilatory abnormalities seen during CO2 exposure. Future studies concerning the effects of antidepressants on responses to CO 2 challenge should use a placebo-controlled design. Copyright © 2009 by Lippincott Williams & Wilkins.