(AP)—The maker of Zoloft is being sued in an unusual case alleging the popular antidepressant has no more benefit than a dummy pill. The federal lawsuit, filed in California, argues that patients who took it should be reimbursed for their costs.

Zoloft's maker, ., disagrees. It says clinical studies and the experience of millions of patients and their doctors over two decades prove Zoloft is effective.

Pfizer and four psychiatry experts interviewed by The Associated Press call the lawsuit frivolous.

But the plaintiff, Laura Plumlee, says Zoloft didn't help her during three years of treatment. Her attorney, R. Brent Wisner, argues the shouldn't have approved Zoloft because Pfizer didn't publish some studies that found the drug about as effective as a placebo.