Endo Pharmaceuticals said Thursday it will voluntarily remove its extended-release opioid painkiller, Opana ER, from the market, after the Food and Drug Administration asked the company last month to remove the drug because of a growing opioid abuse crisis.

Endo, with U.S. headquarters in Malvern, said it expects to incur a "pre-tax impairment charge" of about $20 million in the second quarter. Opana ER had sales of $158.9 million in 2016 and $35.7 million in the first quarter this year, the company said.

The FDA said on June 8 the benefits of Opana ER no longer outweigh the risks. Post-marketing data showed a significant shift in the route of abuse from nasal to injection, the agency said. The drug, first approved in 2006 to manage pain from moderate to severe enough to require daily, around-the-clock, long-term opioid treatment, was reformulated in 2012 with the intent to resist physical and chemical manipulation by snorting or injecting.

Injection abuse of reformulated Opana ER has been associated with a serious outbreak of HIV and hepatitis C, as well as cases of a serious blood disorder known as thrombotic microangiopathy, the FDA said. Endo reiterated that the company thinks the product is safe and effective "when used as intended in appropriate patients."

Endo shares fell 29 cents, or 2.50 percent, to $11.10 in afternoon trading Thursday.