The FDA and Paxil's maker, drug company GlaxoSmithKline, are notifying doctors about the warning, which is being added to the drug's package inserts.
Antidepressants already carry a warning about a possible increase in suicidal thinking and behavior in children and adolescents with depressiondepression and other psychiatric disorders who take antidepressants.
The new Paxil warning focuses on young adults aged 18-30. Paxil (paroxetine) is not approved for patients younger than 18.
"It is important that all patients, especially young adults and those who are improving, receive careful monitoring during paroxetine therapy regardless of the condition being treated," state an FDA news release and GlaxoSmithKline's letter to doctors.
GlaxoSmithKline's letter states that the company "continues to believe that the overall risk: benefit of paroxetine in the treatment of adult patients with MDD [major depressive disorder] and other non-depressive psychiatric disorders remains positive."
About the Warning
GlaxoSmithKline's letter to doctors is posted on the FDA's web site.
The letter states that GlaxoSmithKline recently conducted a new analysis (in addition to numerous previous analyses) of suicidal behavior and suicidal thinking in adults participating in clinical trials of Paxil.
Participants in those clinical trials had psychiatric disorders including MDD, other depression, and nondepression disorders. Nearly 9,000 were taking Paxil and almost 6,000 others were taking a placebo.
The analysis showed a higher frequency of suicidal behavior in young adults (aged 18-24) with Paxil compared with placebo, but not in older adults. The age gap was not statistically significant, meaning it may have been due to chance.
Another analysis focused on adults of all ages with major depressive disorder. The frequency of suicidal behavior was higher among those taking Paxil than placebo, with 11 cases of suicidal behavior among 3,455 patients taking Paxil and one out of 1,978 taking placebo.
Overall, 0.32% of the Paxil patients of all ages with major depressive disorder showed suicidal behavior, compared with 0.05% of those taking placebo.
"All of the reported events of suicidal behavior in the adult patients with MDD were nonfatal suicide attempts, and the majority of these attempts (8 of 11) were in younger adults aged 18-30," states GlaxoSmithKline's letter.
Caution on the Data
The age differences in the frequency of suicidal behavior in adults of all ages with MDD were "statistically significant; however, as the absolute number and incidence of events are small, these data should be interpreted with caution," states GlaxoSmithKline.
Most patients who attempted suicide during the study "had an identified social stressor at the time of the event," the letter notes.
The letter also says that "it is difficult to conclude a causal relationship between paroxetine and suicidality due to the small incidence and absolute number of events, the retrospective nature of this meta-analysis, and potential for confounding by the fact that the events of interest are a symptom of the psychiatric illnesses themselves."
GlaxoSmithKline spokespeople were not immediately available for comment.