Dependence on opioids, in the form of heroin or prescription pain medications, is a significant health concern. A treatment that has been increasing in usage is the medication buprenorphine, with numerous studies supporting the efficacy of sublingually (beneath the tongue) administered buprenorphine. However, poor treatment adherence, resulting in craving and withdrawal symptoms that increase the likelihood of relapse, is a concern, according to background information in the article. To address these problems with adherence and nonmedical use, an implantable formulation of buprenorphine was developed that delivers a constant and low level of buprenorphine. A preliminary open-label phase 2 study reported favorable results with this implant in opioid-dependent patients.

Walter Ling, M.D., of the University of California, Los Angeles, and colleagues conducted a phase 3 study of buprenorphine implants for treatment of opioid dependence at 18 sites in the United States between April 2007 and June 2008. The study included 163 adults, ages 18 to 65 years, diagnosed with opioid dependence. One hundred eight were randomized to receive buprenorphine implants and 55 to receive placebo implants. The implants were placed below the skin in the inner side of the nondominant arm. The 4 buprenorphine implants, each of which gradually released 80 mg of buprenorphine, and the 4 placebo implants, were removed after 6 months. Standardized individual drug counseling was provided to all patients. Opioid use was gauged via urine samples.

During the course of the study, the buprenorphine implant group had significantly more urine samples negative for illicit opioids during weeks 1 through 16. Patients with buprenorphine implants had an average percentage of urine samples that tested negative for illicit opioids of 40.4 percent and a median (midpoint) of 40.7 percent; those in the placebo group had an average of 28.3 percent and a median of 20.8 percent.

Treatment group differences were also evident on additional efficacy measures, with 65.7 percent of patients in the buprenorphine implant group remaining in the study for the full 24-week study period compared to 30.9 percent of patients in the placebo group. No patients in the buprenorphine implant group met the definition of treatment failure; 30.9 percent of placebo patients were classified as treatment failures.

"Those who received buprenorphine implants also had fewer clinician-rated and patient-rated withdrawal symptoms, had lower patient ratings of craving, and experienced a greater change on clinician global ratings of severity of opioid dependence and on the clinician global ratings of improvement than those who received placebo implants," the researchers write.

"In summary, this study found that the use of buprenorphine implants compared with placebo resulted in less opioid use over 16 weeks and also across the full 24 weeks."

Editorial: Advances in the Treatment of Opioid Dependence -- Continued Progress and Ongoing Challenges

Patrick G. O'Connor, M.D., M.P.H., of the Yale University School of Medicine, New Haven, Conn., writes in an accompanying editorial that the study by Ling et al represents a potentially important step forward in the effort to improve and expand the treatment options for opioid dependence.

"Further research is needed to assess how this treatment compares with current opioid maintenance treatment prior to the widespread use of implant buprenorphine in clinical practice. If further research suggests that this buprenorphine implant is as good as or better than current treatment approaches, then the study by Ling et al 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."

Note: If no author is given, the source is cited instead.

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