The drug atorvastatin is probably best known under its brand name, Lipitor. Lipitor is manufactured by Pfizer Pharmaceuticals and falls under a class of drugs called statins. Statins are drugs that reduce bad cholesterol levels and are used to reduce chances of a patient having heart attacks or strokes. Additionally, statins can sometimes increase the levels of good cholesterol.

Lipitor was first approved by the Food and Drug Administration (FDA) in 1996. The primary use of Lipitor as designated by the FDA was preventing cardiovascular disease. Since its original approval, Lipitor has become the top-selling drug worldwide, with worldwide sales reaching over $130 billion and over 29 million prescriptions for the drug in the U.S. alone.

Though Lipitor’s benefits in reducing the risks of cardiovascular disease are relatively undisputed, some side effects of the drug have subjected Pfizer to thousands of lawsuits in recent years. Normal side effects such as diarrhea and upset stomachs were disclosed to patients, but now many patients are claiming that Pfizer did not disclose the possibility of one very serious side effect—type 2 diabetes.

The FDA released a safety communication in 2012 which required manufacturers of statins (like Lipitor) to disclose the fact that usage of statins has been linked to the onset of type 2 diabetes. Although this safety communication was issued, the FDA noted that they continue to believe the benefits of statins outweigh the small increased risks. Pfizer Pharmaceuticals is essentially making the same argument in the current lawsuits against it.

Since 2014, there have been over 2,000 lawsuits filed against Pfizer. Plaintiffs against the drug manufacturer are alleging that Pfizer failed to warn them of the possibility that Lipitor could cause the onset of type 2 diabetes. Most of the pending lawsuits have been consolidated in a multidistrict litigation (MDL) in the U.S. District Court for the District of South Carolina for coordinated pretrial proceedings.

The first trials in the MDL will be the bellwether trials, and the first of those will not be heard until March or April of 2016. Attorneys involved in the current litigation are predicting tens of thousands of additional lawsuits in the future, but it will likely depend on the outcome of the bellwether trials.