Experts seek options on painkiller abuse
Scientists are hunting new ways to help millions of pain sufferers from addiction-resistant narcotics to using brain scanners for biofeedback amid a worrisome rise in abuse of today's top prescription painkillers.
The good news: Only a tiny fraction of patients who are appropriately prescribed the most powerful painkillers drugs known as opioids, including morphine, Vicodin, fentanyl and Oxycontin ever will become dependent on them.
And scientists told the National Institutes of Health last week that those few who are vulnerable tend also to suffer such psychiatric disorders as depression and anxiety, giving doctors a clue about which patients need closer monitoring.
Opioids "are not dangerous if you know how to use them properly," stressed Dr. Nora Volkow, chief of NIH's National Institute on Drug Abuse. "We need to develop the knowledge that maximizes our ability to use them properly."
Amid fears that rising painkiller abuse will spark a backlash against pain sufferers, Volkow organized a two-day meeting involving several hundred scientists and primary care physicians, to bring the latest science on pain and addiction to doctors struggling to balance the drugs' clear benefits and potential harm.
Some form of chronic pain affects one of every three or four adults worldwide. The government says one in 10 Americans suffers pain that lasts a year or more. For millions, pain is severe enough to be disabling; up to 6 million patients are on long-term opioid therapy. It's not just a question of suffering: Serious pain can actually worsen recovery from various ailments.
How many need opioids but don't get them? Those numbers are hard to come by, but "pain is really under-treated in our society," opioid specialist Dr. Christopher Evans of the University of California, Los Angeles, told the NIH meeting.
By some estimates, as many as 40 percent of cancer patients and the terminally ill don't even get those medications.
At the same time, prescription drug abuse, particularly of opioid painkillers, is on the rise. One in 10 high school seniors admits to popping Vicodin for nonmedical purposes, and recent studies suggest about 2.2 million people age 12 and older first abused painkillers in the past year, outpacing new marijuana users. Some 415,000 people received treatment for painkiller abuse last year, Evans said.
So the hunt is on for pain relief that minimizes the abuse risk not just for the 2 percent of pain patients who might become dependent, but to discourage theft or other diversion of the drugs.
"We really need to get smarter," said Dr. Pamela Palmer, director of pain research at the University of California, San Francisco, who laments that the only way now to tell how patients are using painkillers is "making people pee in a bottle to see if the drug I prescribed is in there."
Under research now:
_Pain Therapeutics Inc.'s Remoxy is in late-stage clinical trials to see if it offers an abuse-resistant version of oxycodone, the ingredient in Oxycontin. Oxycontin tablets are supposed to slowly dissolve for long-term pain relief, but abusers crush them and snort or inject the powder for a fast high. Remoxy is a thick gelatin version of oxycodone crushing it just yields goo.
_Also being studied is a combination of naltrexone, a drug used to reduce alcohol craving, with oxycodone. The extra drug should tamp down oxycodone's brain-stimulating effect, Palmer said, but one question is whether that also will diminish pain relief.
_Another approach now in early trials pairs technology with tiny tablets of a hospital-strength opioid, sufentanil, redesigned to dissolve almost instantly under the tongue. A computerized dispenser, the size of a remote control, is programmed with the patient's dose of Nanotabs and records how much is used and how often, information the doctor would require before allowing refills or adjusting doses, says Palmer, who is working with manufacturer AcelRx Pharmaceuticals.
Better would be drugs that more selectively target the brain receptors that react to opioids, blocking multiple ones at the same time so that it's harder to develop tolerance or suffer withdrawal. While that is still years away, an initial attempt worked in rats, and NIDA will push additional research to speed human trials, Volkow said. "That would be an amazing thing."
Then there's the non-drug approach: Omneuron Inc. and Stanford University researchers are trying to teach patients to control how much pain they feel by scanning their brains and showing them the real-time MRI images as they try out different techniques.
"The brain is built to be able to modulate its pain-control processes," says Omneuron chief executive Christopher deCharms. "We're teaching people to gain conscious control."
The first study, with a few chronic pain sufferers plus healthy people given painful zaps, suggests the approach may relieve pain right after participants are trained. Now the question is whether the pain relief is real and lasts. A larger trial to test that is under way.
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