Opana, a powerful opioid painkiller containing oxymorphone, is produced by Endo Pharmaceuticals.

The blood disorder, thrombotic thrombocytopenic purpura, resulted in kidney failure requiring dialysis in some cases and at least one death, the Food and Drug Administration said.

The disorder causes clots to form in small blood vessels throughout the body, limiting or blocking blood flow to the organs.

Platelets, a certain type of blood cell, help the clotting process. When this disorder occurs, however, platelets clump together in the blood clots, making fewer platelets available in the blood in other parts of the body to help clotting there.

This can lead to bleeding under the skin and purple-colored spots called purpura, or to bleeding inside the body.

Thrombotic thrombocytopenic purpura can cause death or lead to other complications with permanent damage, including brain damage and stroke, in addition to kidney failure.

The FDA said problems appear to occur with Opana ER only when it is abused and injected intravenously. Opana ER is meant to be taken orally and should be taken only when prescribed and as directed.

Prescription drug abuse leads to more deaths in the United States than heroin and cocaine combined, and rural residents are nearly twice as likely to overdose on pills than people in big cities, according to the Centers for Disease Control.

Law enforcement officials are alarmed by the rise of Opana abuse, which they said started after Oxycontin was changed in late 2010 to make that drug more difficult to snort or inject for a heroin-like high. Oxycontin is a brand of oxycodone.

Opana abuse can be deadly because it is more potent, per milligram, than Oxycontin and users who are not familiar with how strong it is may be vulnerable to overdosing.

Opana, known by such street names as "stop signs," "the O bomb," and "new blues," is crushed and either snorted or injected. Crushing defeats the pill's "extended release" design, releasing the drug all at once.

(Reporting by Debra Sherman in Chicago; Editing by Dale Hudson and Andre Grenon)

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