What is Hydroxychloroquine?
CAS Number – 118-42-3
Molecular Formula – C18H26ClN3O
Molecular Weight – 335.872 g/mol
Hydroxychloroquine is a disease-modifying anti-rheumatic drug (DMARD). It regulates the activity of the immune system, which may be overactive in some conditions. Hydroxychloroquine can modify the underlying disease process, rather than simply treating the symptoms.
Recent studies have shown 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.
Hydroxychloroquine is used to treat systemic lupus erythematosus, rheumatic disorders like rheumatoid arthritis, porphyria cutanea tarda, Q fever, and certain types of malaria. It is considered the first-line treatment for systemic lupus erythematosus. Certain types of malaria, resistant strains, and complicated cases require different or additional medication.
It is widely used to treat primary Sjögren syndrome but has not been shown to be effective. Hydroxychloroquine is widely used in the treatment of post-Lyme arthritis. It may have both an anti-spirochete activity and an anti-inflammatory activity, similar to the treatment of rheumatoid arthritis.
Hydroxychloroquine may be used as part of combination therapy. That means you may need to take it with other drugs such as methotrexate.
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
COVID-19 and Hydroxychloroquine
Recent studies have shown 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.
Nonetheless, based on these early findings, hospitals worldwide have begun using hydroxychloroquine and chloroquine for patients with COVID-19. On March 28, 2020, the FDA issued an Emergency Use Authorization (EUA) that allows providers to request a supply of hydroxychloroquine or chloroquine for hospitalized patients with COVID-19 who are unable to join a clinical trial. The EUA does not mean that the FDA has approved these medications for the treatment of COVID-19. The intent of the EUA is to help increase access to these medications by allowing doctors to request supplies from the Strategic National Stockpile for these specific cases.
Data is still extremely limited. We need more research to determine the best dose when to give it and for how long, and how the risks and benefits of these medications stack up in the fight against COVID-19.