WASHINGTON (AP) -- The government is evaluating a new version of OxyContin -- the potent painkiller sometimes called "hillbilly heroin" -- designed to be harder to abuse.

A plastic-like coating fuses to the tablet, making it harder to crush -- and turning into a gooey mess if abusers try to inject it, maker Purdue Pharma LP said in documents released by the Food and Drug Administration Thursday.

The FDA will ask its scientific advisers on Monday if the reformulated drug seems tamper-resistant enough to allow on the market, before the required long-term studies are done to see if the changes thwart at least some abuse.

"These are clearly difficult questions for which there are no easy answers," Dr. Bob Rappaport, FDA's chief of painkilling drugs, wrote the advisory panel.

OxyContin was hailed as a breakthrough in the treatment of severe chronic pain when it was introduced in 1996. A time-release version of the old narcotic oxycodone, it was designed to be swallowed whole and digested over 12 hours to keep a steady state of the painkiller in the bodies of seriously ill patients.

But abusers rapidly discovered the tablets can produce a heroin-like high if crushed and snorted or injected, thus dumping the dose all at once instead of letting it seep in slowly.

The U.S. Drug Enforcement Administration found the number of oxycodone-related deaths nationwide had quintupled by 2001, as OxyContin prescriptions soared. The DEA cracked down, but OxyContin abuse steadily spread across the country. And a year ago, Purdue Pharma and some of its executives pleaded guilty to misleading the public about OxyContin's risk of addiction earlier in the decade, and agreed to millions in fines to settle state complaints that it encouraged over-prescribing of the drug.

Against that contentious backdrop, the FDA had urged drug companies to develop more abuse-resistant versions of important painkillers, recognizing, in Rappaport's words, "the importance of maintaining the availability of these important drug products for the millions of patients in this country who suffer from chronic pain."

The remade OxyContin marks the first application for a reformulated painkiller that purports to do that, he wrote.

Purdue Pharma said its laboratory studies show the new OxyContin is equivalent to the original in how well the painkiller dissolves if used correctly.

If someone tries to crush it, the plastic-like coating makes the tablet more likely to break into large fragments instead of a powder, the Stamford, Conn.-based company wrote. The coating renders the drug "a gelatinous mess" when mixed with alcohol or other solvents in attempts to dissolve and inject it, the documents say.

But the FDA cited concerns, including:

_Some people who died from OxyContin abuse swallowed the drug without crushing it. Would the new version mislead doctors or patients into thinking OxyContin is less risky than it really is?

_Lower doses are set to be reformulated initially, with higher doses converted in the future. Does that increase risk from the higher doses in the meantime?

Moreover, "there is no perfect formulation that can resist all forms of tampering," FDA's Rappaport wrote. If approved, the new version's label "would have to be carefully crafted so as to avoid the publication of a road map describing how to defeat these changes."

Two other companies, Pain Therapeutics Inc. and King Pharmaceuticals, also are developing an abuse-resistant form of the drug. Called Remoxy, it would provide a thick gelatin-like version of oxycodone

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