Prescriptions for nerve pain medicines like Neurontin and Lyrica more than tripled in recent years, driven by increased use among chronically ill older adults and patients already taking opioids, a U.S. study suggests.

The United States should take action to reduce demand for the drugs fueling its deadly opioid crisis, a top Chinese drug control official said.

Opioid drug abuse cost the U.S. economy as much as $504 billion in 2015, White House economists said in a report.

“As we continue to confront the staggering human and economic toll created by opioid abuse and addiction, we’re focused on taking actions that reduce the scope of new addiction by decreasing unnecessary exposure to opioids. …”

New Jersey sued Purdue Pharma LP, maker of the chronic pain medication OxyContin, accusing the company of engaging in deceptive marketing practices that contributed to what it called the state’s opioid crisis.