(NEW YORK) -- The move by drug companies to make abuse-proof prescription painkillers may be inadvertently promoting heroin use, a new study found.
The study of more than 2,500 people with opioid dependence found a 17 percent drop in OxyContin abuse with the 2010 arrival of a formula that's harder to inhale or inject. During the same time period, heroin abuse doubled.
"I think the message we have to take away from this is that there are both anticipated consequences and unanticipated consequences to these new formulas," said Theodore Cicero, a professor of psychiatry at Washington University in St. Louis and lead author of the study published today in the New England Journal of Medicine. "Substance abuse is like a balloon: If you press in one spot, it bulges in another."
Unlike its predecessor, the abuse-deterring version of OxyContin turns to gel when crushed, making it harder for people to snort or inject for a rapid high. But nearly a quarter of study participants found a way around the formulation tweak, and 66 percent said they switched to another opioid – usually heroin.
"Most people that I know don't use OxyContin to get high anymore," one participant said, according to the study. "They have moved on to heroin [because] it is easier to use, much cheaper and easily available."
A small bag of heroin – enough for a high – can cost as little as $5, according to Cicero. An 80-milligram dose of OxyContin, on the other hand, can cost up to $80 on the street, according to the U.S. Drug Enforcement Administration.
"The rationale was if we reduced the supply, it would decrease the demand," Cicero said of national efforts to limit access to prescription painkillers and minimize the potential for abuse. "But what we're seeing is the demand is still there and it's driving the procurement of different drugs."
Different, and potentially more dangerous, that is. Whereas the dose of OxyContin is engraved in the pill, heroin powder is usually cut with other chemicals to bolster dealers' profits.
"When people switch over, they don't really know what they're getting," said Cicero. "They don't know the dose or the purity, so overdoses become quite common."
OxyContin maker Purdue Pharma said in a statement, "It is unreasonable to expect the reformulation of one medication by one pharmaceutical company would reduce overall opioid abuse. Rather, these data suggest that reformulating all opioid medications over time to incorporate abuse-deterrent properties may help to reduce the overall abuse of this class of medications."
H. Westley Clark, director of the Center for Substance Abuse Treatment at the U.S. Substance Abuse and Mental Health Services Administration, said the shift to heroin use among people with opioid dependence reflects the challenge of obtaining prescription painkillers.
"Our belief is that those coordinated and comprehensive efforts to curtail the problem of prescription drug abuse are having an impact. Now we have to be concerned about the unintentional consequences," he said.
By ramping up public awareness and cracking down on illicit drug use, Clark hopes to see a downtick in prescription drug abuse without an uptick in heroin use.
"We should not attempt to solve one problem by creating another," he said.
Copyright 2012 ABC News Radio