10 mu g CCK-4 premedication and 35% CO2 challenge in healthy volunteers

1. The purpose of the study was to confirm whether a subtreshold dose of CC K-4 would enhance the vulnerability of healthy subjects to a 35% carbon dio xide challenge. 2. 40 subjects, with no prior or present psychiatric disorder and in good p hysical health were challenged with a vital capacity breath of a 35% carbon dioxide 65% oxygen mixture, immediatly after an intravenous injection of 1 0 mu g CCK-4 or placebo, according to a random order, double blind, separat e group design 3. Subjects reported significantly less anxiety and panic symptoms upon car bon dioxide after premedication with CCK-4 than after placebo. 4. CCK-4 and carbon dioxide seem to inhibit rather than enhance each other' s effects, possibly through an effect on different neurobiological systems.