Hydroxychloroquine (Plaquenil) and chloroquine are two medications that have recently been making headlines as possible treatments for the coronavirus disease (COVID-19). Do these medications actually work against COVID-19? Here’s what we know.
What is hydroxychloroquine, and what is chloroquine?
Hydroxychloroquine is a medication first approved to treat malaria, an infection caused by a parasite. It is similar in structure to chloroquine, which was first approved by the FDA in 1949.
Hydroxychloroquine, approved in 1955, is typically preferred over chloroquine because it has fewer side effects. Side effects for both medications, which are more common at higher doses and with long-term use, include:
- Irreversible visual changes
- Long QT or QT prolongation (abnormal heart rhythm)
- Muscle weakness or nerve pain
- Hypoglycemia (low blood glucose)
- Worsening of psoriasis
What do hydroxychloroquine or chloroquine usually treat?
Hydroxychloroquine and chloroquine were first used to prevent or treat malaria. Both are available as pills that are taken by mouth. Hydroxychloroquine is also approved for long-term use in rheumatoid arthritis and lupus.
The dosage varies depending on what the medications are being used for. On the low end, hydroxychloroquine is taken as 400 mg orally once a week for malaria prevention and should be continued for 4 weeks after leaving an endemic area. On the high end, hydroxychloroquine is taken as 200 mg to 400 mg daily for rheumatoid arthritis.
Why are hydroxychloroquine and chloroquine being mentioned with COVID-19?
In vitro studies (studies done in a petri dish or test tube rather than in animals or humans) previously showed that both hydroxychloroquine and chloroquine have antiviral properties against SARS-CoV-2, the virus that causes COVID-19. In these studies, these medications worked by interfering with the chemical environment of human cell membranes. This blocked the virus from entering and multiplying inside the cells. A medication working in vitro does not always mean that it will work once inside a human body.
Based on these in vitro findings, researchers rushed to study the effects of hydroxychloroquine and chloroquine in hospitalized patients with COVID-19. Early results were shared with the media, which led hospitals worldwide to start using these medications, though some have since stopped.
Data was taken from