In re Warfarin Sodium Litigation, MDL No. 98-1232-SLR, U.S. District Court for the District of Delaware

Nathan provided expert economic testimony on behalf of about 1.8 million consumers of a prescription drug marketed by DuPont Merck Pharmaceuticals under the brand name Coumadin. Used as a blood thinner, Coumadin is one of the most prescribed medicines in the United States. In the late 1990s, the patent for Coumadin expired.

Plaintiffs were a class of end-user, indirect purchasers. According to plaintiffs, DuPont, anticipating competition from Coumadin’s generic counterparts, unlawfully and artificially maintained most of its original exclusive control of the market by disseminating deceptive information to patients, doctors, and pharmacists about the quality and effectiveness of Coumadin’s counterpart, the FDA-approved generic drug, warfarin sodium.

We examined the pharmaceutical industry and its distribution channels and concluded that all of the consumers in the proposed class paid higher prices for Coumadin than they would have paid absent DuPont’s allegedly illegal conduct.

We based our conclusion on the findings that:

  • Absent DuPont’s conduct, more Coumadin consumers would have switched to generic warfarin sodium than actually did, from the time the generic drug was introduced to the present;
  • The price consumers paid for the generic drug would have been significantly lower than the price paid for Coumadin; and
  • DuPont’s price for Coumadin to consumers would have been lower than what it has been.

The court certified the class of Coumadin consumers in June 2000. Dr. Gary L. French estimated class-wide damages under several scenarios and submitted an affidavit for the fairness hearing.

Dr. French estimated that the price differential between Coumadin and the generic alternative was between 25 to 35 percent and that market penetration by the generic had been diminished, resulting in overpayment by consumers.

In August 2002, U.S. District Chief Judge Sue L. Robinson certified a settlement class and approved a settlement of $44.5 million for the plaintiffs. Chief Judge Robinson found that Dr. French’s estimate of the range of possible damages if the case were to go to trial is reasonable.

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