GlaxoSmithKline has reached a $49 million settlement with a class of direct purchasers who accused the drugmaker of bringing “sham” patent litigation against manufacturers of generic versions of its popular antidepressant Wellbutrin SR in an attempt to prolong its monopoly on the market.

A federal judge has certified class action antitrust claims against GlaxoSmithKline, maker of the popular antidepressant drug Wellbutrin XL, for allegedly using sham patent suits to delay generic versions of the drug from making their way to the market.

In a significant win for big pharmaceutical firms, a federal judge has refused to certify a consumer and indirect purchaser antitrust class action against GlaxoSmithKline on the grounds that the plaintiffs cannot prove each class member was affected by the alleged scheme to maintain higher prices. The plaintiffs allege that GSK set out to delay the market date for a generic version of Wellbutrin SR by using “sham” patent litigation to tie up generic manufacturers in court and patent board proceedings.

Generic drug manufacturers are not insulated from lawsuits by an FDA approval process that certifies such drugs as the “bioequivalent” of their brand-name predecessors, a federal judge has ruled. The judge refused to dismiss a suit brought by consumers who were taking Wellbutrin, a brand-name antidepressant, and who claim they had side effects upon switching to a generic. The suit alleges that two drug manufacturers failed to warn the public about differences that affected the release of the product’s active ingredient.

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 antidepressant 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, but U.S.