An NMDAR antagonist (IC50s = 0.93, 0.82, and 0.47 μM at -70 mV for NR1-1a/NR2A, NR1-1a/NR2B, and NR1-1a/NR2D subunit-containing recombinant receptors, respectively, expressed in HEK293 cells); blocks the influenza A M2 proton channel (IC50 = 16 μM for the recombinant channel expressed in Xenopus oocytes) and inhibits cytotoxicity induced by the influenza A strains H1N1 and H3N2 in MDCK cells (EC50s = 34 and 0.84 μM, respectively); improves the survival of mice infected with influenza A when administered 24 hours following viral challenge at a dose of 100 mg/kg per day; decreases L-DOPA-induced dyskinesia in a 6-OHDA hemi-parkinsonian mouse model at 40 mg/kg