The pharmacologic profile of paroxetine, a new selective serotonin reuptake inhibitor.

Paroxetine is a highly potent and selective inhibitor of serotonin reuptake, being more potent in vitro than fluoxetine, fluvoxamine, and sertraline. In contrast to the tricyclic antidepressants, paroxetine has little affinity for catecholaminergic or histaminergic systems. Paroxetine is well absorbed from the gastrointestinal tract and undergoes first-pass metabolism that is partially saturable. Unlike the metabolites of fluoxetine and sertraline, the metabolites of paroxetine are pharmacologically inactive in vivo. Steady-state paroxetine plasma concentrations are generally achieved within 4 to 14 days of commencing therapy and remain stable thereafter. The pharmacokinetics of paroxetine are also consistent with once-daily dosing. This pharmacologic and pharmacokinetic profile, taken together with extensive clinical data, indicates that paroxetine is a valuable addition to the physician's armamentarium for the treatment of depression.