Fluoxetine A bicyclic compound, is the first SSRI to be introduced, and the longest acting. Its plasma t½ is 2 days and that of its active demethylated metabolite is 7–10 days. The longer half life of fluoxetine will avoid any withdrawal symptoms because this medication effectively tears itself from the patient’s system over a few days. Of the SSRIs, fluoxetine may be stopped abruptly without much risk of difficulty.