Imipramine, a TCA, was the first pharmacological agent noted to treat panic disorder (Klein 1964). Other TCAs, notably clomipramine, have also been found to have significant anxiolytic properties (den Boer et al. 1990; Modigh 1992). Studies of ethnic differences in the pharmacokinetics of the TCAs in Asian Americans have led to inconclusive results. Of six studies comparing Asians with Caucasians, three revealed that Asians metabolize TCAs significantly slower than their Caucasian counterparts; however, the differences observed in the other three studies did not reach statistical significance, particularly after controlling for body weight (Kishimoto 1984; Rudorfer 1984; Schneider 1991). Other studies also did not find significant differences in the pharmacokinetics of nortriptyline between Mexican Americans and Caucasians. Pharmacodynamically, results from two clinical studies in Asia indicated that severely depressed hospitalized Asian patients responded clinically to lower combined concentrations of imipramine and desipramine (130 ng/ml) than studies previously reported on North American and European patients (180