Parties in the Xarelto blood-thinner multi-district litigation have been ordered to select which cases will participate in bellwether trials, a sample of cases with similar facts.

Bellwether trials help provide parties from both sides insight about how future juries may rule and also help minimize the inconvenience to the court, the witnesses, the lawyers and the parties. Bellwether cases are used when there are a large number of plaintiffs with similar claims.

The federal judge overseeing the Xarelto litigation in the U.S. District Court in the Eastern District of Louisiana has ordered the parties by June 15 to establish procedures to select the bellwether cases and to begin specific discovery. A proposed case management order detailing the procedures is to be submitted to the court by June 30.

Initially approved by the U.S. Food & Drug Administration in 2011, Xarelto has been widely prescribed as a treatment for stroke prevention in people with atrial fibrillation (arrhythmia of the heart), deep vein thrombosis (blood clots deep within the body) and pulmonary embolism (blood clots in the lungs), stroke, and prevention of deep vein thrombosis in patients undergoing hip or knee replacement surgery.

Xarelto plaintiffs allege that pharmaceutical companies Johnson & Johnson, Bayer, and Janssen Pharmaceutical used misleading marketing to position Xarelto as a superior blood thinner alternative to Coumadin (warfarin) for anticoagulant therapy. Coumadin has been on the market since the 1950s.

Patients taking Coumadin must adhere to dietary restrictions and regularly have their blood checked. Xarelto users does not require regular blood tests or a special diet, two of the drug’s key selling points.

Xarelto lawsuit plaintiffs claim, however, that they were not adequately warned of the risk of severe bleeding, known as a bleedout, as well as the lack of an approved reversal agent for the new-generation blood-thinner. Coumadin bleeding episodes can be reversed by administering vitamin K to the patient.

A black box warning on the Xarelto label includes information about the increased risk of blood clot formation after premature discontinuation of the medication in the absence of adequate alternative anti-coagulation.

Severe internal bleeding and death are Xarelto’s most commonly reported side effects, but others include thrombosis (blood clots), decreased hemoglobin (a substance that carries oxygen in red blood cells), cerebrovascular accidents (an event that leads to a cerebral hemorrhage), hematoma (a semisolid mass in the blood), peripheral edema (swelling of the lower limbs), and dyspnea (difficulty breathing).

Xarelto is in the same class of drugs as Pradaxa (dabigatran), another of the newer anticoagulants also  facing a slew of lawsuits in which plaintiffs have alleged bleeding complications. Pradaxa manufacturers Boehringer Ingelheim GmbH agreed to pay $650 million in a comprehensive settlement of lawsuits brought against Pradaxa.

The settlement was expected to resolve some 4,000 lawsuits brought by plaintiffs in the United States. Researchers linked Pradaxa to more than 500 deaths.