Rodatristat (KAR5417) is a potent tryptophan hydroxylase 1 (TPH1) and TPH2 inhibitor with IC50s value of 33 nM and 7 nM, respectively, and shows robust reduction of intestinal serotonin (5-HT) levels in mice[1].
Rodatristat (10-50 mg/kg; oral administration; mice) treatment decreases intestinal 5-HT concentrations at 50 mg/kg, their efficacy drop off significantly at the lower 10 mg/kg dose[1].
[1]. Goldberg DR, et al. Optimization of spirocyclic proline tryptophan hydroxylase-1 inhibitors. Bioorg Med Chem Lett. 2017 Feb 1;27(3):413-419.