ifferent doses of 10 and 50 mg ninety minutes prior to administration of CCK-4. The trials with different doses of the antagonist were separated by a week washout period. The 20 g dose of CCK-4 was proven to induce panic attack in 75% of the PD sufferers, as established in the earlier dose-response experiment (Bradwejn et al, 1991) and did not change for both trials. According to the experimental design an equal number of patients were supposed to receive placebo, 10 and 50 mg of antagonist. An important feature of this experimentwas that it included not only evaluation of behavioral responses or physiological responses by observation , but also of cardiovascular responses . To record occurrence of panic attack, as in previous studies, a Panic Symptom Scale derived from DSM-III-R was used for assessment immediately following injection of CCK-4 . To measure subjective anxiety a visual analog scale was developed. The results of this study showed that L-365,260 is effective in attenuating symptoms and severity of CCK-induced panic attacks in a dose-dependent manner. The panic rate was 88% for placebo (15 out of 17 participants), 33% for 10 mg dose of antagonist (6 out of 18) and 0% for 50 mg dose. L-365,260 showed significant difference in reducing the number of reported panic symptoms and the sum intensity of symptoms. It did not produce significant effects on the onset and duration of symptoms. Regarding individual PSS measurements, significant effects were found for both somatic and emotional symptoms, such as dyspnea, choking, chest pain/discomfort, palpitations/heart rate as well as anxiety/fear/apprehension and fear of dying. Curiously enough, fear of losing control in the Utrecht sample was less pronounced in those receiving placebo. Cardiovascular response to CCK-4 was recorded only in the Montreal site, and there was significant decrease in maximum heart rate following CCK-4 injection for both 50 and 10 mg of the anta...
