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Sustained-release buprenorphine effective for opioid use disorder
Phase 3 study results indicated efficacy and safety of RB-6000, a subcutaneous long-acting monthly depot injection and sustained-release buprenorphine formulation, for opioid use disorder.
“Opioid use disorder is an underserved disease and we are pleased to add preliminary clinical evidence that supports the efficacy and safety of RBP-6000 in the treatment of this potentially fatal, chronic disease,” Christian Heidbreder, PhD, chief scientific officer of Indivior, said in a press release. “With these compelling phase 3 data in hand, we are on track to complete the data analysis of this phase 3 trial as well as the open-label long-term assessment of the safety and tolerability of RBP-6000 by Q1 2017 in line with previous guidance.”
Researchers conducted a multicenter, randomized, double-blind, placebo-controlled study among 489 individuals with moderate or severe opioid disorder who were not currently in treatment but seeking medication-assisted treatment for the disorder. Study participants received Suboxone sublingual film (buprenorphine/naloxone, Indivior Inc.) for 3 days. Following this, participants completed buprenorphine/naloxone sublingual film dose adjustments, ranging from 8 mg to 24 mg. When participants achieved no significant opioid craving or withdrawal after at least 7 days of buprenorphine/naloxone sublingual film therapy, they were randomized to receive one of two dose regimens of RB-6000 or placebo with six subcutaneous injections every 28 days. Participants who received dose regimen 1 received 300 mg of RB-6000 once on day 1 and then every 28 days thereafter. Those who received dose regimen 2 received 300 mg of RB-6000 once on day 1 and 29 and then four 100 mg injections, once every 28 days.
Study participants who received RB-6000 achieved the primary endpoint of cumulative distribution function of percentage of urine samples negative for opioids and self-reported abstention from illicit opioid use (P < .0001 for both dose regimens vs. placebo).
Both regimens also achieved the secondary endpoint (P < .001 vs. placebo).
RB-6000 was generally well-tolerated, according to researchers.
Serious treatment-emergent adverse events occurred in 2.8% of participants who received RB-6000, compared with 5.1% of those who received placebo.
Discontinuation due to treatment-emergent adverse events occurred in 4.6% of participants who received RB-6000 and 2% of those who received placebo.
“We believe that RBP-6000 can potentially transform the treatment of opioid dependence, if approved, by possibly reducing patients' treatment administration days from 365 a year to 12. RBP-6000 was designed to offer physicians the potential for increased certainty of treatment adherence, and developed with the desire to help mitigate abuse, misuse and diversion of medication,” Shaun Thaxter, BS, CEO of Indivior, said in the release. “We look forward to working with the FDA to bring this important new therapy to patients living with opioid use disorder.”