* "Abuse-deterrent" formulations may not be magic bullet
* Heroin more worrisome because of HIV, hepatitis risks
By Gene Emery
July 11 (Reuters Health) - U.S. drug abusers may be more likely to turn to heroin now that they are finding it harder to snort, inject or smoke a new formulation of the pain-killing opiate OxyContin, researchers said.
The reformulation was introduced in August 2010 by manufacturer Purdue Pharma to make it more difficult to crush the medicine into powder, greatly reducing its appeal to addicts.
But the change may be causing a shift to heroin and other drugs, researchers said in a letter published on Wednesday in the New England Journal of Medicine bit.ly/ORiJss.
In recent interviews, only about 13 percent of addicts with an opioid dependence said OxyContin was their primary drug of abuse, compared to about 36 percent before the new version of the prescription tablet became available.
In the same time period, heroin use doubled among those surveyed. That jump accounted for nearly all of the increase in the use of opioids other than OxyContin, including high-potency fentanyl and hydromorphone.
"They didn't stop (abusing drugs). They turned to something else," said Theodore Cicero of Washington University in St. Louis, lead author of the letter detailing the results. "We should have asked the question, 'If they stop using the most popular drug out there, what are they going to turn to now?'"
Cicero said that when the drug first came out, OxyContin "was advertised by the company and the Food and Drug Administration (FDA) as having a very low abuse potential" because of the slow-release formula.
"What they didn't take into account was that the pill was pretty easy to crush," allowing addicts to snort or inject it to get an immediate rush, Cicero told Reuters Health.
The new formulation becomes a harder-to-manage gel when put in water, or becomes too chunky to snort easily when crushed.
MANY SWITCH TO HEROIN
Cicero and his colleagues gathered their data from anonymous surveys of more than 2,500 addicts. In addition, 103 agreed to be interviewed, online or by telephone.
Getting around the tamper-resistant reformulation is possible, and about a quarter reportedly did so. Yet "a lot of work is entailed in doing that," said Cicero.
Two-thirds "indicated a switch to another opioid, with 'heroin' the most common response," the researchers reported.
The jump in heroin use came in the second quarter of 2011, six months after OxyContin use began a long slide.
"The most amazing thing was how quickly it dropped because they weren't able to extract the drug anymore. They switched to drugs that were potentially more harmful to them," said Cicero.
The researchers quoted one respondent as saying, "Most people that I know don't use OxyContin to get high anymore. They have moved on to heroin (because) it is easier to use, much cheaper, and easily available."
Heroin is more worrisome because intravenous use increases the risk of HIV and hepatitis, and the heroin is often cut with dangerous chemicals, said Cicero.
"Thus, abuse-deterrent formulations may not be the 'magic bullets' that many hoped they would be in solving the growing problem of opioid abuse," he and his team concluded.
In May another group of researchers reported a similar decline based on 11 months of data from patients in 324 drug treatment centers throughout the United States.
That study assessed the experience of patients during the first 11 months after introduction of the new tablets. It found that before the reformulation, about a quarter of people abusing prescription opioids were doing it with OxyContin. The rate subsequently fell to about one in eight.
According to that study, led by Dr. Ryan Black of Inflexxion Inc., in Newton, Massachusetts, those reporting that they snorted, injected or smoked the drug fell to 5 percent. It had been 18 percent.
But the rate of oxymorphine abuse more than doubled, going from about 2 percent to 4.5 percent.
"We need to look at the demand side" when dealing with the problem, said Cicero. "Drug abuse is like a balloon. If you crush one side of the balloon, the volume doesn't go away, it just pops out somewhere else." (Editing by Ivan Oransky and Xavier Briand)