Antiviral activity of arbidol, a broad‐spectrum drug for use against respiratory viruses, varies according to test conditions

The therapeutic activity of arbidol was investigated against representatives of seven different virus families. Its 50% median effective concentration (EC 50) was 0.22-11.8µg/ml (0.41-22nM). Therapeutic indices of 91 were obtained for type 1 poliovirus and 1.9-8.5 for influenza A and B, human paramyxo-3, avian infectious bronchitis-, and Marek's disease viruses.