β-adrenoceptor affinity as a biological predictor of treatment response to paroxetine in patients with acute panic disorder

BackgroundFew studies have reported on the functional differences of the β-adrenoceptor between treatment responders and non-responders in panic disorder (PD). The aim of this study was to compare the nature of the β-adrenoceptor function and clinical variables between treatment responders and non-responders to paroxetine treatment in acute PD patients.MethodParoxetine was administered to all of the panic patients for 12weeks. The lymphocyte β-adrenoceptor density (Bmax), affinity (1/Kd), and sensitivity (cAMP ratio) were measured in 22 untreated outpatients with acute PD and 22 age, sex and BMI matched control subjects. Psychological assessments were conducted using the HAM-A, and HAM-D, STAI-S and STAI-T, Anxiety sensitivity index (ASI), and Acute panic inventory (API).ResultsA significantly higher Kd was observed in the panic patients before treatment as compared with the control subjects, but there was no significant difference in Kd between the panic patients and control subjects after the treatment. Among the 22 patients, the 11 treatment responders (50%) showed a significantly higher Kd and lower mean scores of HAM-D, STAI-S, STAI-T, and ASI at baseline, compared with the non-responders. Logistic regression revealed that the pretreatment Kd and HAM-D were significantly reliable predictors for treatment response (p < 0.05).ConclusionThe β-adrenoceptor affinity (1/Kd) was decreased and adaptively normalized after treatment with paroxetine in the acute panic patients. In addition, a low pretreatment β-adrenoceptor affinity (1/Kd) was found to predict the treatment response and can be suggested as a biological predictor of treatment response in acute PD.