GS-441524-d is the deuterium labeled GS-441524 (HY-103586). GS-441524 is a potent, orally active and CNS-penetrant viral RNA-dependent RNA polymerase inhibitor. GS-441524 competes with natural nucleosides to block viral RNA transcription as an alternative substrate and RNA chain terminator. GS-441524 inhibits the replication of feline infectious peritonitis virus, African swine fever virus, and severe acute respiratory syndrome coronavirus 2. GS-441524 reduces viral RNA levels in cats. GS-441524 can be used in research related to feline infectious peritonitis, African swine fever, and coronavirus disease 2019 (COVID-19)[1][2][3][4][5].