Four drugmakers are on trial over claims they helped fuel the deadly opioid epidemic in the United States

Drugmakers including Johnson & Johnson on Tuesday denied claims they helped fuel the deadly opioid epidemic in the United States through deceptive marketing that downplayed addiction risks, as the trial in a lawsuit filed by several municipalities got underway.

J&J, Teva, Endo and Allergan are accused of trivializing the dangers of long-term use of opioid painkillers to boost sales in a lawsuit filed by three California counties and the city of Oakland. The trial began on Monday.

The complaint seeks billions of dollars in damages for the public impact it says the drugmakers created.

"Defendants prioritized profits over lives and deceived the public about the real dangers of opioids," Santa Clara County attorney James Williams said in a statement.

Almost 500,000 people in the United States have died from overdoses involving prescription or illicit opioids over the past two decades, according to the Centers for Disease Control and Prevention. About 50,000 people died from opioid overdoses in 2019 alone.

The plaintiffs—Santa Clara, Los Angeles and Orange counties, as well as the city of Oakland—represent 15 million people, or 40 percent of the most populous American state.

In addition to the damages, they are asking for measures to prevent deceptive pharmaceutical marketing practices in the future.

Factfile on synthetic opioids, where they come from, how they affect the brain, and a comparison of lethal doses of opioids.

'Blockbuster profits'

"While the use of opioids has taken an enormous toll on the State of California and its residents, Defendants have realized blockbuster profits. In 2014 alone, opioids generated $11 billion in revenue for drug companies like Defendants," the complaint said.

The lawsuit comes at a particularly bad time for J&J.

The pharmaceutical giant, also tainted by a scandal related to its talcum-based baby power, was hoping to restore its reputation with its coronavirus vaccine. But the shot has been suspended in the United States, pending an investigation, after reports that six women had developed serious blood clots.

In a statement on the opioid case, J&J's subsidiary Janssen said it "will challenge plaintiffs' unverified claims at trial, which do not contain any proof of causation."

Teva said in a statement, "While we do remain eager to identifying collaborative solutions to this crisis, we will vigorously defend... against these unproven allegations in Court."

More than 3,000 lawsuits related to the opioid crisis have been filed in US courts.

In 2019, an Oklahoma judge ordered J&J to pay a $465 million fine for downplaying the risks of opioids. J&J is appealing.