A federal judge has dealt a major setback to the “indirect purchaser” plaintiffs in the massive antitrust litigation over the marketing of Wellbutrin XL, a popular anti-depressant drug, by tossing out most of the claims on standing grounds.

The plaintiffs, a group of employee benefit plans, were aiming to pursue the case as a class action alleging claims under the consumer protection laws of 41 states and the antitrust laws of 23 states.