Image of male nurse pushing senior woman in a wheelchair in nursing facility

Consumer watchdog group Public Citizen filed a lawsuit against the Food and Drug Administration Monday saying the agency unreasonably delayed action on removing the antidepressant Serzone from the market.

The drug, with the generic name nefazodone, has resulted in liver failure in 55 patients, including 20 deaths, the group said.

Serzone, marketed by Bristol-Myers Squibb Co., has already been taken off the market in Canada and Europe, and is scheduled to be withdrawn in Australia and New Zealand in May.

Bristol-Myers included a “black box” warning about liver toxicity in its package inserts for Serzone in 2002, company spokesman Robert Hutchison said. “The product continues to be recognized by prescribing physicians as an important therapeutic option for patients suffering from depression,” he said.