Chloroquine (also called chloroquinine) is an antimalarial drug of the 4-aminoquinoline family that has been widely marketed as salts (sulphate or phosphate). Chloroquine, quinine and hydroxychloroquine are the most widely used treatments against malaria, both preventive and curative. This molecule has also shown efficacy in the treatment of certain autoimmune diseases such as lupus and rheumatoid diseases such as rheumatoid arthritis. Chloroquine also shows antiviral effects, although for the time being these have mainly been observed in vitro.

With the COVID-19 pandemic caused by the SARS-CoV-2 virus, chloroquine has attracted interest, along with other molecules, as a potential antiviral. Chloroquine is believed to be effective in vitro in inhibiting the replication of SARS-CoV-2. Chloroquine appears to be responsible for raising the pH of the lysosomes of cells targeted by the virus. However, the efficacy of chloroquine as a treatment in patients infected with CoV-2-SARS has yet to be proven but many studies are ongoing.