Glucosylceramide synthase-IN-3 (compound BZ1) is a highly potent, brain-penetrant, and orally active inhibitor of glucosylceramide synthase (GCS), exhibiting an IC50 value of 16 nM for human GCS. This compound, designated as Glucosylceramide synthase-IN-3, finds potential applications in Gaucher's disease research [1] [2].