Lorcaserin treatment for extended-release naltrexone induction and retention for opioid use disorder individuals: A pilot, placebo-controlled randomized trial

Background: Opioid Use Disorder (OUD) is a significant public health problem associated with severe morbidity and mortality. While effective pharmacotherapies are available, limitations exist with each. Induction onto extended-release naltrexone (XR-NTX) is more difficult than initiation of buprenorphine or methadone, even in inpatient settings, as it is recommended that patients remain abstinent for at least 7 days prior to initiating XR-NTX. The purpose of this trial was to determine if lorcaserin, a 5HT2c agonist, improves outpatient XR-NTX induction rates.

Methods: An 8-week trial beginning with a brief detoxification period and induction onto XR-NTX. Sixty participants with OUD were enrolled in the trial, with 49 participants at the initiation of detoxification randomized to lorcaserin or placebo for 39 days. Additionally, ancillary medications were provided. The primary outcome was the proportion of participants inducted onto the first XR-NTX injection. Secondary outcomes were withdrawal severity (measured by COWS and SOWS) prior to the first injection and the proportion of participants receiving the second XR-NTX injection.

Results: The proportion of participants inducted onto the first (lorcaserin: 36 %; placebo: 44 %; p = .67) and the second XR-NTX injection (lorcaserin: 27 %; placebo: 31 %; p = .77) was not significantly different between treatment arms. Prior to the first injection, withdrawal scores did not significantly differ between treatment arms over time (treatment*time interaction COWS: p = .11; SOWS: p = .39).

Conclusions: Lorcaserin failed to improve outpatient XR-NTX induction rates. Although this study is small, the findings do not support the use of lorcaserin in promoting induction onto XR-NTX or in mitigating withdrawal symptoms.