GS-443902 trisodium (GS-441524 triphosphate trisodium), the active triphosphate metabolite of Remdesivir (GS-5734), serves as a potent inhibitor of viral RNA-dependent RNA-polymerases (RdRp), displaying inhibitory concentrations (IC50) of 1.1 μM and 5 μM for RSV RdRp and HCV RdRp, respectively.

RdRp (RSV):1.1 µM (IC50), HCV RdRp:5 µM (IC50)

In a continuous 72 h incubation of 1 μM Remdesivir (GS-5734), the GS-443902 trisodium (GS-441524 triphosphate trisodium; Remdesivir metabolite trisodium) level is measured at 2, 24, 48 and 72 h, and reaches a C max of 300, 110, and 90 pmol/million cells in macrophages, HMVEC, and HeLa cells lines respectively[1]. GS-443902 trisodium (compound 8a) is a triphosphates (TP) derivative[2]. GS-443902 trisodium (NTP; 0.01, 0.1, 1, 10, 100 μM) inhibits RSV RdRp-catalysed RNA synthesis by incorporating into the nascent viral RNA transcript and causing its premature termination. GS-5734 selectively inhibits EBOV replication by targeting its RdRp and inhibiting viral RNA synthesis following efficient intracellular conversion to GS-443902 sodium[3].

Remdesivir (GS-5734; 10?mg?kg; i.v.) rapidly distributes into peripheral blood mononuclear cells (PBMCs), and efficient conversion to GS-443902 trisodium (Remdesivir metabolite trisodium; NTP) is apparent within 2?h of dose administration in rhesus monkeys. In PBMCs, GS-443902 trisodium represents the predominant metabolite and is persistent with a t 1/2 of 14?h and levels required for >50% virus inhibition for 24?hours[3].