Update: Wednesday, March 18, 2020 (9.20 PM EST) —New controlled clinical study conducted by doctors ​in France shows that Hydroxychloroquine cures 100% of coronavirus patients within 6 days of treatment (covidtrial.io)

On March 16, we covered a story about new academic study that revealed over-the-counter anti-malaria med Chloroquine may be highly effective at treating coronavirus. The study presented by Thomas R. Broker, (Stanford PhD), James M. Todaro (Columbia MD), and Gregory J. Rigano, Esq., in consultation with Stanford University School of Medicine, UAB School of Medicine, and National Academy of Sciences researchers, shows that over the counter anti-malaria pills Chloroquine may be highly effective at treating coronavirus COVID-19. Chloroquine is a drug has been used since World War II for treating and suppressing malaria.

Today, we have another piece of good news to share with you. A new study by the United States National Institutes of Health (NIH) shows that the sister drug hydroxychloroquine is more potent in killing the virus off in vitro (in the test tube to not in the body). In a study titled: “In Vitro Antiviral Activity and Projection of Optimized Dosing Design of Hydroxychloroquine for the Treatment of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2),” the result of the study shows that Hydroxychloroquine was found to be more potent than chloroquine to inhibit SARS-CoV-2 in vitro.

According to the study, the researchers tested the pharmacological activity of chloroquine and hydroxychloroquine using SARS-CoV-2 infected Vero cells. They then implemented physiologically-based pharmacokinetic models (PBPK) for both drugs separately by integrating their in vitro data. Using the PBPK models, hydroxychloroquine concentrations in lung fluid were simulated under 5 different dosing regimens to explore the most effective regimen whilst considering the drug’s safety profile.

Based on PBPK models results, a loading dose of 400 mg twice daily of hydroxychloroquine sulfate given orally, followed by a maintenance dose of 200 mg given twice daily for 4 days is recommended for SARS-CoV-2 infection, as it reached three times the potency of chloroquine phosphate when given 500 mg twice daily 5 days in advance.

Below is the abstract of the study published at NIH website. You can download the PDF version of the study here.

BACKGROUND: The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) first broke out in Wuhan (China) and subsequently spread worldwide. Chloroquine has been sporadically used in treating SARS-CoV-2 infection. Hydroxychloroquine shares the same mechanism of action as chloroquine, but its more tolerable safety profile makes it the preferred drug to treat malaria and autoimmune conditions. We propose that the immunomodulatory effect of hydroxychloroquine also may be useful in controlling the cytokine storm that occurs late-phase in critically ill SARS-CoV-2 infected patients. Currently, there is no evidence to support the use of hydroxychloroquine in SARS-CoV-2 infection. METHODS: The pharmacological activity of chloroquine and hydroxychloroquine was tested using SARS-CoV-2 infected Vero cells. Physiologically-based pharmacokinetic models (PBPK) were implemented for both drugs separately by integrating their in vitro data. Using the PBPK models, hydroxychloroquine concentrations in lung fluid were simulated under 5 different dosing regimens to explore the most effective regimen whilst considering the drug’s safety profile. RESULTS: Hydroxychloroquine (EC50=0.72 μM) was found to be more potent than chloroquine (EC50=5.47 μM) in vitro. Based on PBPK models results, a loading dose of 400 mg twice daily of hydroxychloroquine sulfate given orally, followed by a maintenance dose of 200 mg given twice daily for 4 days is recommended for SARS-CoV-2 infection, as it reached three times the potency of chloroquine phosphate when given 500 mg twice daily 5 days in advance. CONCLUSIONS: Hydroxychloroquine was found to be more potent than chloroquine to inhibit SARS-CoV-2 in vitro.