Generic medications should be the equivalent of brand medications with the exception of their price. Before a generic medication is introduced, its bioequivalence within a window of 80 to 125% of the original has to be demonstrated. There are reports that this criterion is not always followed in post-marketed periods. Such investigations were triggered by the observation that some patients previously stable on original medications relapsed when switched to a presumable equivalent generic. Several factors could account for this problem. Given reports of such problems occurring with the antidepressants citalopram and venlafaxine, some pharmacokinetic properties of specific brands of generics and the originals will be examined for these two medications. Twelve healthy male volunteers will participate in this crossover study. It is anticipated that there will be significant differences emerging between the two formulations given the clinical reports of patients deteriorating when switched from the original to the generic preparations.