The Food and Drug Administration pulled Fenfluramine from the market in 1997 after studies linked the drug to heart valve damage.
On Thursday, the company agreed to not only pay some six million people who say they were injured by fenfluramine, but to also pay for the future monitoring of people who took the drug, but have not discovered side effects.
"We believe this is one of the most important public health settlements from a consumer prospective in the history of this country," says Chris Placitella, who was the lead "class action" negotiator in the case.
American Home Products, based in Madison, N.J., made fenfluramine, the "fen" in the fen-phen combination, and gave the drug a brand name of Pondimin. It also made Redux, a chemical cousin which is covered in the settlement.
If a judge approves the deal, people with heart valve problems blamed on fen-phen will get as much as $1.5 million each. Healthy former users will be able to get such benefits as $30 prescription refunds and free checkups. The settlement covers all people who took the drug, whether they sued or not.
In a statement, the company says "the settlement provides fair and equitable terms for both diet drug claimants and American Home Products," adding that "studies show no increased risk of valvular heart disease among persons who took drugs for three months or less."
However, the settlement comes just when the connection between these diet drugs and heart damage is less certain, reports CBS This Morning Health Correspondent Dr. Emily Senay.
Harvard researchers recently published a study in the Journal of the American College of Cardiology that found no correlation between using the diet drugs and heart damage.
Indeed, when researchers went back and looked at people who participated in a weight loss study using these drugs, they found no more leaky heart valves than occur in the general population.
Placitella told CBS News he is not worried about an appeal because the previous studies were strong evidence and AHP decided to enter the deal despite the latest findings.
Mark Marcketta, a plaintiff in the case, was the original "poster boy" for Redux. His 'Before' and 'After' pictures were used in advertisements for the drug and in medical journals.
After the drug was pulled off the market, he went in for tests.
"I was on the drug for 15 months. I do have the heart valve problems at this point," he says.
He says he will discuss his options with his lawyer, but is glad to know that testing will be available to everyone who may have been affected by the drug.
Placitella agrees that the availabilit of testing is a key result of the settlement.
"We've made special provisions for the poor who cannot afford echocardiograms and the proper testing to make sure they are not put in the position of having to choose between their health and money. And for that, we thank American Home at this point," Placitella says.
Doctors began prescribing fenfluramine in the mid-1990s for weight loss along with phentermine, which was never associated with health problems and is still sold.
Payments will begin this year and continue for about 16 years. With interest earned, the total amount paid could rise to $4.83 billion, easily surpassing such other large product-liability settlements as Dow Corning's $3.2 billion payment to women with silicone breast implants.
American Home has set up a toll-free telephone number (800-386-2070) to provide information on the settlement. Information is also available on the Internet at www.settlementdietdrugs.com.