Aug. 13 (Bloomberg) -- King Pharmaceuticals Inc., the drugmaker betting its future on safer painkillers, won U.S. approval to sell the first pain pill that users may not easily manipulate to get high.

The Food and Drug Administration cleared the extended- release morphine product, Embeda, the agency said today in an e- mail. Embeda contains a chemical designed to counteract the morphine if the capsule is crushed, chewed or dissolved in alcohol to get the full dose at once. The company said, and the FDA agreed, the evidence wasn’t conclusive that the chemical truly interfered with the morphine high.

King moves in front of at least five companies that have been racing to develop new painkillers with chemical or physical features to deter the most common methods of abuse. The approval also justifies the Bristol, Tennessee-based company’s $1.3 billion December acquisition of Alpharma, which developed Embeda and submitted it to the FDA on June 30, 2008, analysts said.

“We’ve been waiting for this approval for several months - - it’s very exciting,” said Gary Nachman, an analyst at Leerink Swann & Co. in New York. “It is the key catalyst for King’s stock that investors have been focused on. The FDA’s approval helps validate the whole abuse deterrent category, and King has other products in this area behind Embeda that it’s working on.”

King gained 44 cents, or 4.3 percent, to $10.57 at 2:27 p.m. when New York Stock Exchange composite trading was halted pending news about the company. King has fallen less than 1 percent so far this year, as investors wait for new products to replace revenue lost when its former top-selling heart pill Altace went generic in late 2007.

Estimated $300 Million

Embeda sales may be $300 million in 2012, said Corey Davis, an analyst at Natixis Bleichroeder in New York, in a June 24 note to clients. King still awaits an FDA decision on Remoxy, a tamper-resistant pill to compete with closely held Purdue Pharma LP’s OxyContin, and Acurox, a short-acting oxycodone pill that guards against overdose.

Doctors considered extended-release pain drugs such as OxyContin a major breakthrough when they were introduced in the mid-1990s for cancer and chronic pain. Regulators then realized that teenagers and adults could manipulate the drugs to get high and they have urged companies to develop tamper-resistant alternatives.

Almost 5 percent of high school seniors say they have used OxyContin, according to the National Institute on Drug Abuse’s 2008 Monitoring the Future Survey. About 5.2 million Americans ages 12 and older misuse prescription painkillers, according to the latest National Survey on Drug Use and Health.

Extra Ingredient

Embeda capsules contain pellets of long-acting morphine surrounding a sequestered core of naltrexone, an antagonist used to help wean addicts off opioid painkillers. If taken as directed, the naltrexone passes through the system without any effect. If the capsules are crushed or chewed, the naltrexone is released to counteract the sense of euphoria from the morphine, according to the company.

The prescribing information and medication guide will include data about two studies that show no evidence the naltrexone reduces euphoria when Embeda is crushed or chewed, Karen Riley, an FDA spokeswoman, said in an e-mail.

A boxed warning, the agency’s strictest, will be part of the prescribing information. The warning notes that drug is not to be crushed, dissolved or chewed and misuse can produce a potentially fatal overdose, Riley said.

To contact the reporter on this story: Catherine Larkin in Washington at clarkin4@bloomberg.net.

Last Updated: August 13, 2009 16:26 EDT