In this randomized study all patients received 12 sessions of CBT and were randomized to either D-cycloserine (n=87) or placebo (n=82) given 1 hour prior to the start of sessions 3 to 7.1

Reference:
1. Hofmann SG, Smits JA, Rosenfield D, et al. D-cycloserine as an augmentation strategy with cognitive-behavioral therapy for social anxiety disorder. Am J Psychiatry 2013; 170 (7): 751–758.