An implant to keep heroin addicts off street drugs?

Effective anti-addiction treatments are only available in liquid and pill forms at this point, but addicts often skip doses or sell the medications on the street to buy heroin.

"The reason the implant was made is that it really solves these problems," said Katherine L. Beebe of California-based Titan Pharmaceuticals, developer of the new product and sponsor of the study.

"The results that we saw were very, very encouraging and consistent with earlier results," added Beebe, whose findings appear in the Journal of the American Medical Association.

Still, more testing needs to be done before the company can apply for approval by the Food and Drug Administration to market the implants as an addiction treatment.

"There is very little data on implant treatment in opioid replacement therapy," said Dr. Patrick G. O'Connor, an addiction expert at Yale School of Medicine in New Haven, Connecticut, who was not involved in the research.

"In fact, this study is the first well-controlled study of its use," he told Reuters Health.

The implant, called Probuphine, is an inch-long rod that sits just underneath the skin of the arm. During its six-month lifespan, the implant releases a steady trickle of buprenorphine, an anti-addiction medicine approved in pill form since 2002. Like methadone, it is a chemical cousin of heroin and decreases drug cravings without producing the same high.

In the new study, 163 addicts dependent on heroin or related drugs were randomly assigned to receive either four dummy implants or four real implants.

After four months, urine samples showed that 40 percent of those with Probuphine implants tested negative for street drugs; two-thirds completed the trial.

Addicts with dummy implants didn't do as well: Only 28 percent had negative urine samples, and less than a third continued until the end.

"The trial was a big success," said Dr. Walter Ling, a psychiatrist at the University of California, Los Angeles, who led the study.

On buprenorphine, he said, addicts can lead a more normal life without constantly looking for the next heroin fix, and they are able to work and drive.

The drug has side effects such nausea, vomiting, and constipation, but Ling said the implant appeared to be well tolerated, despite some swelling and itching at the wound site.

"The concept is a good one," said O'Connor, who wrote an editorial about the findings. "This study really shows that it's a technology with significant promise that should be pursued."

But he said several questions needed to be addressed. For one, the implant should be compared with active treatments, such as methadone or buprenorphine pills, and not just dummy implants, he said. Second, the implant didn't completely eliminate the need for pills in all patients. And last, how addicts in the real world will respond to the implant is still up in the air.

"Moving forward with this approach, safety is going to be a major focus," O'Connor told Reuters Health.

An estimated 3.7 million people in the US have used heroin at some point in their lives, according to the National Institute on Drug Abuse. Of current users, studies suggest that some 200,000 spend time in jails each year.

While so-called opioid replacement therapy does not cure their addiction, studies have shown it cuts crime rates and prevents the spread of diseases by dirty needles and unhealthy living.

Sunil Bhonsle, Titan's CEO, said buprenorphine dominated the US market for opioid addiction treatment. In 2009, he added, sales reached more than $900 million nationally, and $250 million in the rest of the world.

The company hopes to submit their drug application to the FDA in 2012. At this point, it is too early to say anything about pricing.

SOURCE: link.reuters.com/buj28p Journal of the American Medical Association, October 13, 2010.