PC786 is a potent and selective non-nucleoside RSV L-protein polymerase inhibitor for inhalation therapy of RSV infections, with antiviral activity against RSV-A (IC50=0.09-0.71 nM) and RSV-B (IC 50=1.3-50.6 nM), and the ability to inhibit RSV RNA-dependent RNA polymerase in HEp-2 cells ( RdRp).

RSV A:<0.09–0.71 nM, RdRp (RSV, cell-free enzyme assay):14.11 μM, RdRp (RSV, minigenome assay in HEp-2 cells):0.5 nM, RSV B:1.3–50.6 nM

PC786 exhibits strong antiviral activity against RSV-A (IC₅₀: <0.09–0.71 nM) and RSV-B (IC₅₀: 1.3–50.6 nM) in HEp-2 cells, with no detectable cytotoxicity.[1]
PCR analysis confirmed inhibition of RSV replication, and PC786 potently inhibited RSV RNA-dependent RNA polymerase (RdRp) activity in both a cell-free enzyme assay (IC₅₀: 2.1 nM) and a minigenome assay in HEp-2 cells (IC₅₀: 0.5 nM).[1]

Treatment with PC786 (either intratracheal or intranasal; Once-daily on days-1 to 3), is found to inhibit viral loads in the lungs of RSV A2-infected BALB/c mice. The viral load is below the level of detection when the drug is given at 2 mg/mL (40 μg/mouse [approximately 1.6 mg/kg of body weight] for i.t. treatment, or 80 μg/mouse [approximately 3.2 mg/kg] for i.n. treatment)[1].