CHEMISTRY OF THE BRAIN: MOLECULES, MOOD, AND MENTAL ILLNESS - Chemistry: Notable Research and Discoveries - page 87

The molecular structure of Prozac—carbon atoms are shown
in green, oxygen pink, nitrogen blue, fluorine orange, and hy-
drogen white. (Dr Tim Evans/Photo Researchers, Inc.)
in depression. Yet proving the assertion was difficult. For example,
CSF measurements of the main metabolite of serotonin, 5-HIAA, in
depressed patients showed lower concentrations in some cases, but
normal in others. Physicians who tried to relieve depression by giving
patients large doses of the amino acid tryptophan—from which neu-
rons make serotonin—did not succeed. But the effectiveness of SSRIs
would seem to erase any doubt—if their effectiveness could be shown to
depend on their serotonin activities.
The problem is that all drugs exert a number of different effects,
some of which are wanted and some of which are not (the side effects).
In researching the activity of fluoxetine (Prozac), scientists noticed a dis-
crepancy between the time the drug acts on serotonin transporters and
the time at which the patient's symptoms are relieved. Many patients do