GPR61 Inverse agonist 2 is a selective inverse agonist of GPR61, with an IC50 of 6.2 nM in humans and 20 nM in mice, and a Ki of 0.21 nM in humans and 0.72 nM in mice. It binds to an intracellular allosteric pocket of GPR61 induced by the receptor, disrupting its interaction with Gαs and eliminating its constitutive activity. Importantly, GPR61 Inverse agonist 2 does not affect food intake or body weight in healthy mice and is relevant for research in cachexia/sarcopenia.