A new report from the drug company GlaxoSmithKline concludes that its antidepressant Paxil might make adults with major depression more likely to become suicidal.
But the rate of suicide attempts was low, at 0.34 percent for people on Paxil and 0.05 percent for people who got sham treatment with a placebo pill in clinical trials.
And it couldn't be entirely ruled out that the difference was due to chance, according to the report, published in the Journal of Clinical Psychiatry.
"The scientific evidence does not establish that paroxetine" - the ingredient in Paxil -- "causes suicide, suicide attempts, self-harm or suicidal thinking," said Sarah Alspach, a spokeswoman for the drug company.
"Nonetheless, all patients who are started on antidepressant therapy should be monitored appropriately and observed closely for clinical worsening, suicidality, or unusual changes in behavior."
In general, antidepressants can be extremely helpful for people with depression. The American Academy of Family Physicians says on its web site, "Most people who have depression get better with treatment that includes these medicines."
But the link between suicide risk and antidepressants has long been a thorny issue for regulators and drugmakers alike. The current data were initially published in 2006 on GlaxoSmithKline's website in response to widespread concern.
In 2004, the U.S. Food and Drug Administration (FDA) issued a warning that children and adolescents taking antidepressants might have an increased risk of suicidal thoughts and behaviors.
Specifically, the agency found that 4 percent of children taking antidepressants in clinical trials thought about killing or harming themselves, or actually attempted suicide.
By comparison, only 2 percent of children on fake medications did so.
In 2006, the FDA extended its warning to include young adults up to age 25. All antidepressant labels must now carry a "black box" warning stating that they can increase a person's likelihood of suicidal thoughts and behaviors.
For adults, though, the picture has been less than clear-cut.
GlaxoSmithKline's report was based on 57 trials of Paxil for different psychiatric illnesses, involving a total of nearly 15,000 patients. Overall, the drug did not appear to increase suicidal thoughts and behavior.
The authors did see a difference when zooming in on 18- to 24-years-olds; 2.58 percent of Paxil users thought about or attempted suicide, compared to 1.29 percent of study participants on placebo treatment.
Again, that finding could have been due to chance because of the low rate of suicidal behavior.
The 19 trials that included only people with major depressive disorder also found a difference. Among 3,455 Paxil users, 0.34% attempted or succeeded at suicide, compared to 0.05% of the 1,978 people getting placebo.
And most of the suicide attempts were seen in young adults.
Despite those troubling findings, the report notes that Paxil was effective overall at treating symptoms of mental illness.
"Paxil has proven efficacy and has helped many people battling mental illness lead more productive, happier lives," GSK's Alspach told Reuters Health in an email.
According to the Centers for Disease Control and Prevention, antidepressants are one of the most commonly prescribed drug classes in the U.S. One study found that 10 percent of the U.S. population was taking these medications in 2005.
Last year, researchers found that the suicide risk among children is virtually the same for a wide range of antidepressants -- including Prozac (fluoxetine), Zoloft (sertraline) and Paxil (paroxetine).
People who are taking antidepressants should never stop taking them without talking to their doctor, because stopping too quickly can cause side effects.
People who are having suicidal thoughts should talk to their doctor; they can also call the free, 24-hour National Suicide Prevention Lifeline at 1-800-273-TALK (8255), or go online to http://www.suicidepreventionlifeline.org/.
SOURCE: http://bit.ly/hADiCH Journal of Clinical Psychiatry, online February 22, 2011.