Members of the billionaire Sackler family who control Purdue Pharma LP have agreed to fork over as much as $6 billion in a settlement with state governments for their role in fueling the U.S. opioid epidemic -- a massive step in clawing back billions of dollars from the family's fortune to support addiction treatment centers nationwide, according to a court filing on Thursday.

The deal comes after years of litigation over Purdue Pharma's marketing of the OxyContin painkiller that subsequentially sparked the opioid crisis, claiming the lives of more than half a million Americans over the last two decades. 

Attorney generals of eight states and the District of Columbia announced the deal after rejecting a $4.3 billion cash payment from the Sacklers.