(Reuters) - Eight drug companies on Tuesday urged a federal appeals court to disqualify the judge overseeing nationwide opioid litigation, in a last-ditch effort to avoid having him preside over a landmark trial in three weeks.

FILE PHOTO: Cataldo Ambulance medics Ricky Cormio (L) and Luke Magnant take a 40-year-old woman out of a grocery store where she was found unresponsive in the store's bathroom after overdosing on opioids in the Boston suburb of Malden, Massachusetts, U.S., November 15, 2017. REUTERS/Brian Snyder/File Photo

The request came six days after U.S. District Judge Dan Polster in Cleveland refused to recuse himself and said he had done nothing to favor the state and local governments suing for damages, including by encouraging settlements.

But the eight pharmacy chains and drug distributors told the 6th U.S. Circuit Court of Appeals in Cincinnati that Polster has “lost sight” of his responsibility to appear unbiased, including by acknowledging a “personal mission” to address the opioid crisis.

Polster oversees more than 2,300 of the roughly 2,600 lawsuits brought by state, local and tribal governments, hospitals and other entities seeking to hold the drug industry responsible for the toll of opioid abuse.

The scheduled Oct. 21 trial is the first in a federal court.

Ohio’s Cuyahoga and Summit counties, the only plaintiffs, want $8 billion of damages, according to the eight companies.

“The time for disqualification is now,” the companies said.

They added that removing Polster would help preserve “public confidence in the integrity of the judicial system. That should be a special imperative in this litigation, which is so much in the public eye.”

The companies include retailers CVS Health Corp, Rite Aid Corp, Walgreens Boots Alliance Inc and Walmart Inc, and distributors AmerisourceBergen Corp, Cardinal Health Inc, Henry Schein Inc and McKesson Corp.

Their disqualification request, originally made directly to Polster on Sept. 14, followed several rulings against them.

Legal experts have called the effort to remove Polster a long shot, saying it is common for judges to encourage settlements and that disqualifications are rare.

Ohio, 13 other states and Washington, D.C. have separately asked the appeals court to halt the upcoming trial, saying it undermines their right to litigate on their own.

Opioid addiction claimed roughly 400,000 lives in the United States from 1999 to 2017, according to the U.S. Centers for Disease Control and Prevention.