Compounds to treat chronic pain represent a multibillion-dollar market opportunity for drugmakers, as innovative new pain drugs make certain specialty pharmaceutical companies bucketloads of cash. Will King Pharmaceuticals (NYSE:KG) and Pain Therapeutics (NASDAQ:PTIE) join the club? They'll find out soon, thanks to this week's good news that the FDA will review their new pain drug candidate by the end of the year.

Remoxy is Pain, King, and drug-delivery specialist DURECT's (NASDAQ:DRRX) abuse-deterrent version of the perhaps too-successful chronic pain drug OxyContin. Marketing partner King has been waiting for its date with the FDA since June, when it filed a New Drug Application seeking Remoxy's approval.

On Tuesday, the FDA not only accepted the application, but also gave Remoxy a Priority Review designation, trimming its standard 10-month review period to a mere six months. Many other compounds have faced arbitrary FDA review delays this year. But save for Amgen's (NASDAQ:AMGN) and GlaxoSmithKline's (NYSE:GSK) blood disorder drugs, most drug candidates with a priority review this year, like Johnson and Johnson's (NYSE:JNJ) Intelence, Cephalon's Treanda, and Sirion Therapeutics' Durezol, have not. Investors looking to use options or other time-sensitive hedging strategies can thus take some solace in the fact that the FDA will probably issue an approval decision on Remoxy around Dec. 10, give or take a few days.

The FDA gives Priority Review designation to compounds that may "provide a significant improvement compared to (already) marketed products." According to an older look at FDA drug approvals from Booz Allen Hamilton, priority-review-designated drugs have historically enjoyed a 62% success rate of regulatory approval on their first go-around, compared to 34% for drugs that receive a standard review.

During its second-quarter earnings conference call, King thought it "likely" that the FDA would request an advisory panel hearing prior to Remoxy's December PDUFA date. While such hearings are never 100% predictors of how the agency will rule, one could give us a better idea of where Remoxy stands in the FDA's eyes.

Meanwhile, rival Alpharma (NYSE:ALO) is awaiting word on its own abuse-deterrent painkiller, Embeda. After withdrawing from the review process earlier this year, Alpharma resubmitted its marketing application for Embeda in June. If it also gets a priority review, Alpharma and King could both potentially get approval decisions back from the FDA in December, in time to launch their drug sales in the first quarter.

Both of these compounds trail OxyContin developer Purdue Pharma's own abuse-deterrent version of OxyContin, but Purdue's got long odds of gaining marketing approval first, following an unfavorable FDA panel hearing in May. Whatever happens, the abuse-deterrent drug war should only intensify in the coming months.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. GlaxoSmithKline and Johnson and Johnson are active Income Investor picks. The Fool's disclosure policy has a date with destiny.