Jefferson County authorities found a "therapeutic" amount of Luvox in Harris' system after he died, according to a 1999 release by the coroner's office. Luvox is a psychotropic drug allowed only in the United States for obsessive-compulsive disorder, according to the website of its maker, Solvay Pharmaceuticals Inc.

Families believe officials at Solvay failed to warn Harris' doctor about side effects, saying the drug spurs "emotional blunting or disinhibition," according to the suit filed in U.S. District Court.

"Such drugs caused Eric Harris to become manic and psychotic," the suit states.

Solvay Pharmaceuticals has factories all over the world, with main offices in Switzerland. No one in its American office, based in Atlanta, could not be reached Saturday, but the company's website warns that side effects of Luvox include nausea and weight loss, and that it may impair judgment, thinking or motor skills.

It is unclear in the suit or in Harris' autopsy what precise level of Luvox was in his blood when he died or how long he was taking the drug.

The American Psychiatric Association defended Luvox in 1999, stating in a memo, "Despite a decade of research, there is little causal relationship between the use of antidepressant medications and destructive behavior."

Hirsch Fishbein, an Aurora pharmacist not involved in the case, said Luvox is an uncommon drug. "It's not used very often at all," he said. "Most doctors use Paxil or Prozac."

Luvox is a serotonin uptake inhibitor, which means it keeps serotonin flowing through the body. Serotonin, produced naturally by the brain, counters psychotic tendencies.

Filing the suit were families of students Mark Taylor, Evan Todd, Brian Anderson, Cory DePooter and teacher Dave Sanders. DePooter and Sanders were killed.

They are seeking damages in excess of $75,000 each.