• A double-blind, placebo-controlled comparison at three collaborating university sites included 242 patients diagnosed as having anxiety disorders. A two-week placebo washout period preceded random assignment to eight weeks of imipramine hydrochloride, chlordiazepoxide hydrochloride, or placebo treatment. Antianxiety effects of imipramine were superior to those of the other two agents by the second treatment week; these effects became more clearly significant thereafter and were independent of degree of both baseline depression and anxiety. Excluding patients with possible panic-phobic syndromes from the analyses removed most significant antiphobic and antidepressant effects of imipramine but left intact imipramine's significantly superior antianxiety effects.
Kahn RJ, McNair DM, Lipman RS, Covi L, Rickels K, Downing R, Fisher S, Frankenthaler LM. Imipramine and Chlordiazepoxide in Depressive and Anxiety DisordersII. Efficacy in Anxious Outpatients. Arch Gen Psychiatry. 1986;43(1):79-85. doi:10.1001/archpsyc.1986.01800010081010