Houston ? A widely prescribed antidepressant that Andrea Yates took in the months before she drowned her five children in 2001 had homicidal thoughts added recently to its list of rare adverse events. But the drug’s manufacturer says it believes Effexor doesn’t cause such phenomena.

Wyeth spokeswoman Gwen Fisher said that while Effexor was being studied for use in treating panic disorder, the company found one person reported having homicidal thoughts in its clinical trial.

“Homicidal ideation” was added last year as one of Effexor’s rare adverse events, defined as something not proven to be caused by the drug. The Madison, N.J.-based company never notified doctors or issued warning labels because it found no causal link between its drug and homicidal thoughts, Fisher said.

The U.S. Food and Drug Administration defines rare as occurring in less than one in 1,000 people. In the U.S. alone, about 19.2 million prescriptions for Effexor were filled last year.

“We believe there is no causal link between Effexor and homicidality,” Fisher said. “In our minds, we’ve taken every precaution.”