Chloroquine has shown some promise in the treatment of COVID-19. This generic drug was approved by the FDA to treat malaria in 1949, but its origins can be traced back hundreds of years to South America. The Andean population used bark from the cinchona tree to treat shivering. The bark was brought to Europe by missionaries where it was used to treat malaria. The substance in the bark responsible for the clinical benefits was eventually isolated, creating the synthetic drug chloroquine. After decades of use, the parasite responsible for malaria has developed widespread resistance to chloroquine. With the development of new antimalarials, chloroquine is used mostly as preventative medication for malaria.
The relatively low cost, high availability, and anti-viral properties of chloroquine have made it a reasonable candidate to treat COVID-19. Chloroquine may slow down viruses from entering cells, interfering with infection and the rate of replication. This would give a patient’s immune system more time to fight off the virus and may also help activate the body’s immune response.
Early data from studies in France and China have shown that chloroquine might be successful in treating COVID-19 by preventing the worsening of pneumonia, improving lung function, and shortening the amount of time a patient is infected. This data needs to be verified with proper clinical trials, but these preliminary studies have flaws. For example, one study from France was only done with 42 participants, where only 26 patients took the medication. Of the patients that took the medication, 6 dropped out of the study, 3 of them were sent to intensive care, and one patient passed away.
The use of chloroquine should also be proceeded with caution because of potential toxicity which can cause an overdose with acute poisoning and death. There may also be other potential side-effects, especially when taken with other medications. In fact, different versions of chloroquine were developed to create a less toxic drug. Hydroxychloroquine, for example, is 40% less toxic than its predecessor and is FDA approved for the treatment of rheumatoid arthritis and lupus. Hydroxychloroquine is also being tested in clinical trials for the treatment of COVID-19 as it may also interfere with the infection and replication of the virus.
There are a number of clinical studies using chloroquine and hydroxychloroquine to treat COVID-19 taking place in multiple locations. Full clinical trials are needed to determine if the drugs are truly effective against COVID-19 and what dose is safe to use.
For more information on a study, or to find a location near you, please visit clinicaltrials.gov.
Below is a list of some of the available clinical studies using chloroquine and hydroxychloroquine to treat COVID-19.
Chloroquine Prevention of Coronavirus Disease (COVID-19) in the Healthcare Setting (COPCOV)
ClinicalTrials.gov Identifier: NCT04303507
Description: 10,000 participants that are healthcare workers, or other individuals at significant risk of contracting COVID-19 and are at least 16 years old will be recruited onto the study. They will be randomized to prophylaxis treatment of chloroquine, or placebo. The treatment will be taken for 3 months, or until they are diagnosed with COVID-19. The study will look at the number of infections as well as the severity and duration.
Proactive Prophylaxis with Azithromycin and Chloroquine (ProPAC-COVID)
ClinicalTrials.gov Identifier: NCT04322396
Description: 226 participants diagnosed and hospitalized for with COVID-19, 18 years or older, will be randomized to placebo or hydroxychloroquine with azithromycin. This study is looking to see if the treatment can shorten hospitalization, reduce the need of ventilation, reduce the number of patients admitted to intensive care units and death.
Chloroquine Diphosphate for Respiratory Syndrome Secondary to SARS-CoV2 (CloroCOVID19)
ClinicalTrials.gov Identifier: CT04323527
Description: 440 participants diagnosed with COVID-19, 18 years or older, will be randomized to two different treatment arms, either a high dose of chloroquine or a low dose.
Hydroxychloroquine Chemoprophylaxis in Healthcare Personnel in Contact With COVID-19 Patients (PHYDRA Trial) (PHYDRA)
ClinicalTrials.gov Identifier: NCT04252664
Description: 400 participants that are healthcare personnel and exposed to patients with COVID-19, 18 years or older, will be randomized to prophylaxis treatment with hydroxychloroquine or placebo. The study will look at the infection rate.
Hydroxychloroquine Post Exposure Prophylaxis for Coronavirus Disease (COVID-19)
ClinicalTrials.gov Identifier: NCT04318444
Description: 1600 participants, 18 years or older, that were in the same household as a COVID-19 patient in New York City will be randomized to prophylaxis treatment with hydroxychloroquine or placebo. The study will look at the infection rate.