Analysis: Anti-depressants tied to violence

WASHINGTON, Sept. 11 (UPI) -- Two studies released Monday may bring further scrutiny upon the beleaguered selective serotonin reuptake inhibitor class of anti-depressants.

One study suggests the drugs may increase the risk of severe violence, and the other indicates the drugs can have damaging effects on the environment.

SSRIs have come under fire since 2004, when it was revealed they increased the risk of suicide in adolescents and children, a finding that got them slapped with a black-box warning from the Food and Drug Administration.

Now David Healy from Cardiff University and his colleagues are raising questions about the link between this class of drugs and violent behavior. Healy's team looked specifically at GlaxoSmithKline's Paxil and concluded the drug raises the risk of severe violence in a small percentage of people.

"We've got good evidence that the drugs can make people violent and you'd have to reason from that that there may be more episodes of violence," Healy told United Press International. The findings, which are based in part on clinical trial data GSK submitted to the UK's Committee on Safety of Medicines Expert Working Group, appear in the journal Public Library of Science Medicine.

However, the risk of SSRI-induced violence is still very low, and there is no indication that as use of the medications has increased, rates of violence in general have gone up. This could be due to the lack of good data on rates of violence in the United States and the United Kingdom or that some people who may have become violent are being helped by the drugs and are not acting out.

Other drugs in this class -- such as Eli Lilly's Prozac, Forest's Celexa, Pfizer's Zoloft and Wyeth's Effexor -- likely pose the same risk of violence, Healy said.

"I have no reason to think all of the drugs in the group don't pose just as much risk," he said. "We need all of the companies to put their data on this risk out there so we can have a look at it."

More data could help elucidate whether there are certain subpopulations that are vulnerable to violent behavior induced by these medications.

The risk of severe violence is already noted on labeling, but Healy said he thought it was important to put out his study to emphasize this class of drugs is not without severe side effects.

The FDA could do its part to make the risk of violent behavior clearer on labeling, but ultimately the burden may fall on the manufacturers as well as psychiatrists and other prescribers, he said.

"The FDA can look at all of these things until the cows come home, but putting on warnings doesn't actually solve the problem," Healy said. "What the companies have done for years and years is put up this message that there is no risk to these drugs, so the onus is more on the companies to let people know that there is this risk."

In the study, Healy's team looked at GSK's clinical trial data and found a higher rate of hostile events (0.38 percent to 0.66 percent) in patients taking Paxil than in patients taking other anti-depressants.

Interestingly, the rate of hostile events was even higher in healthy volunteers who were given Paxil, which suggests that people with low-grade or no symptoms may be most at risk of this side effect, he said.

"You have to wonder what they could be doing if they're really being handed out to people who just don't really need them," he said.

GlaxoSmithKline did not return a phone call from UPI requesting comment by press time.

In a separate study, Rebecca Heltsley of the National Institute of Standards and Technology's Hollings Marine Laboratory in Charleston, S.C., and colleagues looked at the environmental effects of Prozac, which can leach into lakes and streams via wastewater, and concluded that the SSRI could potentially threaten the future of native freshwater mussels.

In the study, which is slated to be presented this week at the American Chemical Society meeting in San Francisco, Heltsley's team found that female freshwater mussels in laboratory tanks released their larvae prematurely when exposed to concentrations of Prozac that have been found in lakes and streams.

The mussels, many species of which are extinct or endangered, play a key role in filtering the water of rivers and streams and are an important food source for several animals, including muskrats, otters and fish.

"The results from this study were quite alarming," Heltsley said. "When larvae are released too early, they are not viable, which only contributes to the problems faced by struggling populations of native freshwater mussels."

Eli Lilly dismissed the study, saying it was scientifically unsound and not supported by any other research.

"To date, no study by any respected, peer-reviewed scientific body has established a causal relationship between pharmaceuticals in the environment and risk to either human health or the environment," Joan Todd, spokeswoman for Lilly, told UPI.

Todd faulted the study design, saying the artificial conditions used in the experiment do not mimic the complexities of natural settings.

"We wonder if the study has any scientific significance," she added.