Surreptitious drug use by patients in a panic disorder study.
Clark DB., Taylor CB., Roth WT., Hayward C., Ehlers A., Margraf J., Agras WS.
In a double-blind, placebo-controlled trial comparing alprazolam and imipramine for panic disorder, serum analysis revealed that a substantial proportion of the patients took explicitly prohibited anxiolytic medication. Excluding these patients changed the results.