For instance, G-protein-biased μ-opioid receptor (MOR) activation using the ligands like TRV130, PZM21, and SR17018, may provide analgesia without the associated side effects of opioids including respiratory depression (Viscusi et al., 2016; Dahan et al., 2018; Elango et al., 2021). This evidence concerns the gene OPRM1 and respiratory depression.