Laninamivir (R 125489) is a potent influenza neuraminidase (NA) inhibitor with IC 50 s of 0.90 nM, 1.83 nM and 3.12 nM for avian H12N5 NA (N5), pH1N1 N1 NA (p09N1) and A/RI/5+/1957 H2N2 N2 (p57N2), respectively In Vitro Laninamivir (R 125489) inhibits efficiently common oseltamivir-resistant viruses, including those with the ubiquitous His274Tyr substitution. Laninamivir (R 125489) is potent against p57N2, p09N1 and N5 with a similar binding mode to Zanamivir. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:IC50: 0.90 nM (N5), 1.83 nM (p09N1), 3.12 nM (p57N2)