A Single-Dose Study to Evaluate the Relative Bioavailability, Safety, and Tolerability of Monthly Extended-Release...

Buprenorphine extended-release monthly formulation (BUP-XR, SUBLOCADE^®) is approved for treatment of moderate-to-severe opioid use disorder (OUD) following subcutaneous injection in the abdomen. This open-label pharmacokinetic study assessed three alternative injection locations (upper arm, thigh, buttocks) to offer additional flexibility considering the chronic nature of the disease and patient preferences.

Following stabilization on 12/3 mg/day of sublingual buprenorphine/naloxone for ≥ 7 days, participants with moderate-to-severe OUD were randomized to receive a single 300-mg BUP-XR injection in the upper arm, thigh, buttocks, or abdomen (reference). Serial blood samples were taken to measure buprenorphine plasma concentrations over 28 days and assess buprenorphine relative bioavailability. Safety evaluations included treatment-emergent adverse events and assessments of injection site pain, tenderness, erythema, induration, and swelling.

A total of 88 participants received a single subcutaneous injection of 300-mg BUP-XR in the upper arm (N = 21), thigh (N = 23), buttocks (N = 22), or abdomen (N = 22); 81/88 (92%) completed the study. Buprenorphine plasma exposure (area under the plasma concentration-time curve over 28 days) was comparable across injection site groups with mean buprenorphine plasma concentrations sustained at approximately 2 ng/mL (therapeutic target concentration) or above. Buprenorphine maximum plasma concentration (C_max) was approximately 39% and 52% higher after injection in the upper arm and thigh, respectively, versus the abdomen, while comparable between buttocks and abdomen. Higher C_max values were not associated with an increased incidence of adverse events. Safety and injection site tolerability were comparable across injection groups.

These pharmacokinetic and safety findings support BUP-XR injection into the upper arm, thigh, and buttocks.

Clinicaltrials.gov: NCT05704543.