dcyphr | Chloroquine for the 2019 novel coronavirus SARS-CoV-2


Dcyphr summaries are not a substitute for medical advice. Always consult your physician before taking any new drugs or changing your diet in any way. The data on the current COVID-19 outbreak is also changing, so there may be updates.


The authors aim to explain the origins of chloroquine and its current use. They expand what this means for the current COVID-19 outbreak.


Drug repositioning is finding an alternative use for another drug. Drug repositioning has gained momentum in recent years. It is important to use drugs that are safe, where the molecular mechanism and optimal dosage is known. In the current novel coronavirus (SARS-Cov-2) outbreak, many drugs are possibly repositioned, especially chloroquine. Researchers have studied chloroquine for the past 20 years. Researchers have found chloroquine to be effective in vitro against many viruses. This drug increases the pH of the phagolysosome. The phagolysosome is a cytoplasmic body that decreases the pH of the surroundings to kill pathogens during phagocytosis. Thus, chloroquine impairs low pH-dependent activities in viral replication, including fusion and uncoating. Other mechanisms of antiviral activity are not explained well.

During the severe acute respiratory syndrome (SARS)-associated coronavirus in 2003, chloroquine was effective in vitro. It has a 50%% effective concentration (EC50) of about 8 µM. These findings were forgotten when SARS disappeared. The novel coronavirus caused a re-evaluation of many drugs. The new antiviral drug remdesivir and chloroquine are effective against virus replication with an EC50 of 1.1 µM.

Chloroquine is one of the most prescribed drugs today. For the past two decades, Europeans have taken chloroquine to prevent malaria when visiting areas with prevalent malaria. Local residents have taken chloroquine regularly. Treatment often uses chloroquine. Physicians use hydroxychloroquine to treat autoimmune diseases at high doses (up to 600 mg/day). The cost is negligible. Thus, it is reasonable that chloroquine may be used as prevention and a cure for the novel coronavirus. Chinese researchers are currently evaluating chloroquine.