Remdesivir and GS-441524 are antiviral drugs that have been examined for the treatment of COVID-19 caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2). Remdesivir is a nucleotide analogue inhibitor that can inhibit the replication of animal and human coronaviruses. Since it is a prodrug it needs to be metabolized into a pharmacologically active metabolite.
GS-441524 is the nucleoside of Remdesivir and its predominant metabolite. Remdesivir diffuses into cells where it is metabolized and inhibits viral RNA polymerase in order to prevent replication of the virus by chain termination during RNA replication. Remdesivir is already approved for emergency use to treat COVID-19 in different countries, in contrast to GS-441524 which is still being discussed at this time.