A 19-year-old college student who had shown no outward signs of depression killed herself over the weekend at an Eli Lilly & Company laboratory in Indianapolis where she had been participating in a company drug trial for an experimental antidepressant.

The student, Traci Johnson, was one of 25 healthy patients at an Eli Lilly clinic who were being given larger than therapeutic doses of duloxetine, which will be known as Cymbalta if it is introduced as an antidepressant. Four days before her death, Ms. Johnson was taken off Cymbalta and given a placebo.

While Eli Lilly asserted that it had properly screened Ms. Johnson before the study started to ensure that she was healthy and had no mental problems, her death is being used by critics of a popular class of antidepressants to bolster their case that the widely used drugs carry the risk of suicidal tendencies for a small number of people, particularly young people.

Four other patients who were given the drug during earlier trials also committed suicide, the company said. The drug is being tested not only as an antidepressant but also as a possible treatment for stress urinary incontinence.