In an editorial titled "Should journals stop publishing research funded by the drug industry? " in the British Medical Journal the authors make the following claim:
Another dire example is antipsychotics. Many recent drug industry crimes are related to off-label promotion of antipsychotics, and in the United States they were the most sold drugs in 2009. However, they are so dangerous that just one of them, olanzapine (Zyprexa), has probably caused 200 000 deaths.
The citation for this claim is the book "Deadly medicines and organised crime: how big pharma has corrupted health care." by Peter C. Gøtzsche, one of the authors of the editorial.
The number of deaths mentioned in this claim seems extremely large to me, and I wonder how the authors arrived at this number and how credible it is.