Trial has begun in a Risperdal lawsuit in Pennsylvania over allegations that the drug caused abnormal breast growth in an 11-year-old boy.

Plaintiff Timothy S. of Wisconsin says that manufacturer Janssen Pharmaceuticals and its parent company Johnson & Johnson improperly marketed its antipsychotic medication Risperdal for uses in children that were not approved by the FDA.

He says that promotional effort led Timothy’s neurologist to prescribe Risperdal for him without fully understanding the risk of Risperdal male breast growth.

Timothy suffers from Tourette’s syndrome. He alleges his doctor prescribed him Risperdal in February 2006 as a treatment for the twitches associated with that condition. According to Timothy’s Risperdal lawsuit, the FDA has never approved Risperdal as a treatment for Tourette’s.

He kept taking Risperdal for three years, after which time he says he developed abnormal and permanent breast tissue – a condition that in males is known as gynecomastia.

Timothy also says he gained some weight while taking Risperdal. Though he was eventually able to lose that weight, the gynecomastia did not resolve on its own. Ultimately he had to undergo surgery to have the breast tissue removed.

Timothy now argues that the warning label at the time he first took Risperdal understated the risk of Risperdal gynecomastia. The label at that time indicated that Risperdal gynecomastia occurred in fewer than one out of every 1,000 adult patients.

However, Timothy says J&J had at that time that showed Risperdal gynecomastia occurred much more often in young men. The warning label has since been updated to show that Risperdal gynecomastia occurred in 2.3 percent of adolescent patients.

Timothy also argues that defendants Janssen and J&J had actively promoted Risperdal for use in children long before it had been approved for any patients other than adults. From the time it was first approved by the FDA in 1993, Risperdal was not approved for use in younger patients until October 2006.

Johnson & Johnson argues that it can’t be proven that Risperdal caused Timothy’s gynecomastia. They point out that Timothy did not begin developing abnormal breast tissue until a year after he stopped taking Risperdal.

The defendants also say that Timothy’s prolactin levels had never been tested. Prolactin is a hormone associated with breast development. Risperdal, by blocking the effects of dopamine which controls the release of prolactin, can result in increased levels of prolactin which themselves can lead to gynecomastia.

Risperdal, also known by its generic name risperidone, has been a clear financial success for Janssen and J&J, with sales reaching as high as $4.5 billion in 2007. Risperdal is now approved as a treatment for schizophrenia, acute manic or mixed episodes of bipolar I disorder, and irritability associated with autistic disorder.

Two other Risperdal lawsuits in Philadelphia have yielded mixed results. In February 2015, a jury found that Risperdal caused the plaintiff’s gynecomastia and awarded him $2.5 million. In a later trial, while the jury found that Janssen’s warnings were inadequate, they also did not find enough evidence to prove causation.

The Risperdal Lawsuit is pending in the Court of Common Pleas in Philadelphia, Case No. 130401984.