FDA chief defends controversial Zohydra painkiller as criticism intensifies

Debate over a powerful new painkiller ratcheted up Thursday as the head of the Food and Drug Administration defended the drug's approval and a West Virginia Senator responded with a bill to force it off the market.

FDA Commissioner Dr. Margaret Hamburg told Senate lawmakers that the recently-launched Zohydro fills an "important and unique niche" for treating chronic pain. Her agency has been under fire for clearing the drug since December, amid concerns from lawmakers, addiction specialists and others that the drug will exacerbate the national epidemic of prescription drug abuse.

Zohydro is the first single-ingredient hydrocodone drug ever cleared for U.S. patients. Each extended-release pill contains up to five times more of the narcotic than previously available combination pills, such as Vicodin. Pharmacies began dispensing the drug earlier this week.

Hours after Hamburg's appearance on Capitol Hill, Senator Joe Manchin, D-W. Va., introduced a bill that would force the FDA to withdraw the drug and prohibit the approval of any similar medications that don't have tamper-resistant design features.

"I have tried reasoning with the FDA, and I've repeatedly requested the agency change its course on this dangerous drug," Manchin said in a statement. "Because of this painkiller's high potential for misuse and abuse, Zohydro poses a severely dangerous threat to our communities in West Virginia and across our country."

Representative Stephen Lynch, D-Mass., introduced similar legislation in the House of Representatives.

In a statement late Thursday, Hamburg said the FDA has not had a chance to review the legislation.

"However, I look forward to continuing to work with Congress on preserving access to medications for patients suffering from pain, while addressing a serious public health problem - the inappropriate use of opioids."

Hydrocodone is the most frequently abused prescription drug in the U.S., according to the Drug Enforcement Agency. The Centers for Disease Control and Prevention reported that hydrocodone and other prescription opiates accounted for more than 16,650 deaths in 2010, a fourfold increase from 1999.

The opiate class includes drugs that mimic the effect of the opium poppy, such as morphine, oxycodone and heroin. Doctors prescribe opiates to treat pain from injuries, surgery, cancer, arthritis and a variety of other ailments. The drugs can unleash intense feelings of euphoria and well-being, especially when quickly absorbed via injection or inhalation.

Before Zohydro's approval, hydrocodone was available only in combinations with other non-addictive pain relievers, such as acetaminophen.

Hamburg pointed out Thursday that acetaminophen has its own well-known safety risks, including potentially deadly liver damage when taken at high levels. Zohydro provides doctors and patients with a "single hydrocodone product without that associated liver toxicity risk," Hamburg said.

Chief among the criticisms leveled at the FDA is that regulators should have required Zohydro to be formulated in a way that would make it difficult for abusers to chew, crush or dissolve. Any of those approaches can quickly release a massive, heroin-like dose of the drug which can be fatal.

Hamburg cautioned that tamper-resistant formulations are still in the early stages of development. To date, the FDA has only approved one medication with such features, a tamper-resistant version of OxyContin in 2010.

"It doesn't do any good to label something as abuse deterrent if it isn't actually abuse deterrent, and right now, unfortunately, the technology is poor," Hamburg said.