Which selective serotonin reuptake inhibitor is most likely to remain in serum long after being discontinued?

The correct choice is Prozac, which is fluoxetine. This selective serotonin reuptake inhibitor (SSRI) has a long half-life of about 2 to 4 days for the parent compound and up to 16 days for its active metabolite, norfluoxetine. This prolonged half-life means that fluoxetine remains in the system for an extended time, even after discontinuation. Consequently, it can take several weeks before drug levels drop significantly, which is an important consideration in managing potential withdrawal symptoms or side effects when the medication is stopped.

In contrast, medications like Celexa (citalopram), Paxil (paroxetine), and Zoloft (sertraline) have shorter half-lives, which means they are cleared from the body much quicker. This leads to a more rapid cessation of effects after discontinuation, making them less likely to remain detectable in the serum long after stopping the medication.