The Vertex drug is a milestone after a long history of unsuccessful efforts to develop painkillers without the addictive potential of opioids.

The prescription pills, sold under the brand name Journavx and made by Vertex Pharmaceuticals, are taken twice a day and represent the first new class of pain medications in 20 years—and the first non-opioid painkiller since that class first appeared on the market in the 1980s.