An implantable form of a medication used to treat opioid addiction appears to reduce illicit drug use and avoids the issues of patients failing to take their prescription or selling pills on the street.
The medication, called buprenorphine, has been available in pill form since 2008 in Canada and for several years longer in the United States to help addicts kick their dependence on such drugs as heroin and Oxycontin.
Essentially, the medication works by blocking the euphoria of full-blown opiates like heroin while producing its own milder effect that stops withdrawal symptoms and cuts cravings.
Unlike the heroin-replacement drug methadone, which typically is available only through highly regulated clinics, buprenorphine is prescribed by doctors, so patients can take the medication at home.
Now researchers are testing buprenorphine in implantable form — four doses that go under the skin of one arm and provide a round-the-clock, low-dose release of the drug for six months.
“What buprenorphine does from the patient’s point of view is you have this one single treatment in six months and you don’t have to think about it every day,” said Dr. Walter Ling, principal investigator of a study on the implantable form of the drug.
“When you are treating the patient, what you hope to achieve is that if they are not now so preoccupied by using drugs all the time, they will do something else which will change their life,” Ling said.
The buprenorphine implant, called Probuphine, is being developed by U.S.-based Titan Pharmaceuticals Inc. But the drug requires further testing and government approval before it would be available for patients.
Ling, a professor of psychiatry and neuroscience at the University of California, Los Angeles, led a study of Probuphine involving 163 adults aged 18 to 65 with opioid dependence. The paper is published in this week’s edition of the Journal of the American Medical Association.
To conduct the 2007-2008 study, 108 of the participants were randomized to receive Probuphine and 55 to get sham implants. Drug counselling was provided to all subjects and opioid use was gauged by urine-sample testing.
Across the 24-weeks study, patients given the drug-containing implant had significantly more opioid-negative urine samples than the placebo group and a far lower study drop-out rate.
Those given Probuphine had fewer withdrawal symptoms and reported less intense cravings than the placebo group, the study found.
Dependence on opioids, in the form of heroin or prescription pain medications like Oxycontin, is a growing health concern.
The World Health Organization estimates that 2.8 million people in Europe and the United States are addicted to opiates such as heroin, and more than two million in the U.S. alone are dependent on prescription opioid medications. Canadians rank third in the world in the use of prescription opioids, just behind the U.S. and Germany, statistics show.
“Buprenorphine is probably the most important advance in treating opiate addiction since the introduction of methadone,” said Ling.
“The introduction of buprenorphine is giving back the treatment of heroin addiction, or all opiate addiction, to the hands of the physicians. So for me that’s the big change.”
But in pill form, at least, the drug comes with its own list of concerns, he said, explaining that doctors have no way of knowing if their patients are taking the medication as prescribed or selling the pills to others. Implanting the drug would negate both those issues, said Ling, who heads UCLA’s Integrated Substance Abuse Programs.
In an editorial accompanying the study, Dr. Patrick O’Connor of the Yale University School of Medicine, says the study findings represent a potentially important step forward in treating opiate dependence.
“If further research suggests that this buprenorphine implant is as good as or better than current treatment approaches,” O’Connor writes, “then the study ... would represent a major advance in the substantial and continued progress that has occurred in the treatment of opioid dependence since methadone maintenance began in the 1960s.”