Hypercapneic ventilatory response in patients with panic disorder before and after alprazolam treatment and in pre- and postmenstrual women.

We tested the ventilatory and anxiety response to hypercapneic (CO2) challenge in women with panic disorder as well as in normal women in the premenstrual phase and mid-points of their menstrual cycles. Panic disorder patients were challenged on two occasions, each time while in the premenstrual phase of the menstrual cycle, receiving an open trial of alprazolam through the intervening 8 weeks between tests. This study confirms previous reports indicating increased sensitivity to CO2 in patients with panic disorder and that this sensitivity can be attenuated by treatment. We found a significant decrease in the ventilatory response of panic disorder patients comparing pre- and post-therapy. We also observed that normal females, while in the premenstrual phase of their menstrual cycle, have a heightened anxiety response to CO2 challenge.