Buprenorphine-3-glucuronide
Buprenorphine-3-glucuronide (B3G) is a major active metabolite of the opioid modulator buprenorphine. It has affinity for the μ-opioid receptor (Ki = 4.9 (± 2.7) pM), δ-opioid receptor (Ki = 270 nM), and nociceptin receptor (Ki = 36 μM), but not for the κ-opioid receptor.
Source: Wikipedia — Buprenorphine-3-glucuronide (CC BY-SA 4.0)