A long-acting medication designed to help wean substance abusers off opioids is as effective as short-term therapies such as buprenorphine and methadone that patients must take every day, researchers reported Tuesday.

The first major head-to-head comparison of medically assisted treatment approaches confirms that users now have two research-based options, according to the team of scientists led by Joshua D. Lee and John Rotrosen of New York University Medical School.

But each method also showed a distinct disadvantage.

The short-acting medicines must be taken every day for years and sometimes for a lifetime – a difficult regimen for many substance abusers to follow, especially in rural areas that may be far fromdispensing clinics. Monthly injections of naltrexone, in contrast, cannot be started until users have fully detoxified from opioids, which more than 25 percent of the subjects in that part of the research study failed to do.

"This provides an alternative medication for patients that may not have responded to buprenorphine . . . or patients who eventually want to be taken off their medication," said Nora Volkow, director of the National Institute on Drug Abuse, the government agency that funded the research.

In addition, more than half the opioid users in the study relapsed at least once, regardless of which medication they were taking – evidence of how difficult it is to conquer addiction.

Medically assisted treatment is widely considered the most successful way to recover from a substance use disorder. But according to President Donald Trump's commission on opioids, only 10 percent of the 21 million people with substance abuse disorders receive any kind of treatment.

The medications are "incredibly useful and we are lucky to have them," Volkow said. "But we need to provide alternatives to patients who need them."

Richard Pops, chief executive officer of Alkermes, the company that makes Vivitrol, said in a statement that "these data confirm and build upon the body of evidence supporting medication-assisted treatment, and Vivitrol is an important element of the nation's response to treating opioid dependence."

The study was published Tuesday in the journal The Lancet.

The researchers recruited 570 illegal opioid users, mainly heroin addicts, from community health clinics across the country and divided them into two groups that were both followed for 24 weeks. One group was treated with monthly Vivitrol shots while the other received daily doses of suboxone, a combination of buprenorphine and naloxone, made by Invidior.

Vivitrol works by binding to opioid receptors in the brain and blocking other drugs from doing the same. Patients must undergo detox first, which usually takes several days and can take longer. More than a quarter of the group scheduled to receive Vivitrol injections did not make it through that phase.

Suboxone essentially replaces opioids in those receptors without creating the same euphoria users crave, so detoxification is not necessary. The naloxone included in the drug would cause withdrawal if a user tried to snort or inject it. And it must be taken long-term, every day, which many find difficult.

When the researchers measured relapses, overdoses, fatalities and other criteria for the people that were able to begin treatment, they found that the results were essentially the same.

"They look surprisingly similar in terms of how people then did over time," Lee said. "The rates of good outcomes were pretty much the same, side by side. And that's new data."

A previous, smaller study in Norway that did not account for people who failed the detox period produced similar results.

More than half the subjects in the U.S. study dropped out or relapsed, a result that the researchers said was not surprising among long-term heroin users, who are often unemployed, homeless and using other drugs. Long-term treatment, including counseling, will be needed to curb the opioid crisis, the researchers said.

"I think we need to look at addiction, much like hypertension, as a chronic disease," Rotrosen said.