Chloroquine and Hydroxychloroquine
COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused widespread fear and panic affecting thousands of individuals throughout the world since December 2019. Recently, there have discussions and even recommendations regarding treatment options for this highly contagious and often fatal disease. Some of those treatment options include drugs such as chloroquine and hydroxychloroquine.
What is chloroquine or hydroxychloroquine?
Hydroxychloroquine is a derivative of chloroquine, which both have antimalarial and anti-inflammatory activities that are commonly used to treat systemic lupus erythematosis (SLE), rheumatoid arthritis (RA), and malaria1.
How do these drugs work on COVID19?
Chloroquine has been sporadically used in treatment of COVID-19 infection. Hydroxychloroquine shares the same mechanism of action as chloroquine but has a more tolerable safety profile making it a preferred drug2. These drugs likely have multiple mechanisms of action that appear similar but likely interfere with the cellular receptor ACE2 (located on type II alveolar cells in the lungs where the virus binds) and causes impairment of acidification of endosomes that interferes with virus trafficking within the cells3.
What are the side effects or contraindications?
Contraindications include known hypersensitivity to medications, myasthenia gravis, prolonged QT interval, epilepsy due to reduced seizure thresholds, and retinal pathology. Serious adverse events that can occur include Torsades de pointes, cardiomyopathy, bone marrow suppression, retinal toxicity that may be irreversible, neuromyopathy, and hypoglycemia. Caution is recommended in those with hepatic impairment, G6PD deficiency, porphyria, psoriasis, and renal disease4.
So what’s next?
Well, there is currently a study underway in China to evaluate the efficacy and safety of hydroxychloroquine in the treatment of pneumonia caused by SARS-CoV-25. Hydroxychloroquine is currently under investigation in clinical trials for pre-exposure and post-exposure prophylaxis as well. In the United States, several clinical trials of hydroxychloroquine for prophylaxis or treatment of COVID-19 are planned or will be enrolling soon6. In one highly referenced study, there was even a possible synergistic effect of hydroxychloroquine when combined with the antibiotic, azithromycin7. Hopefully, results continue to be promising and reinforce an international strategy to fight this emerging infection.