In vitro antiviral activity of doxycycline against SARS-CoV-2
Main result
The cytotoxicity evaluation of doxycycline showed that the CC50 value was > 100 µM for 48h. The median effective concentration (EC50) was 5.6 ± 0.4 µM.
Doxycycline was found to decrease the SARS-CoV-2 replication in vitro in a concentration dependent manner. Besides its antiviral activity, doxycycline has anti-inflammatory effects by decreasing the expression of IL1, IL6 , IL8 and TNF alpha. This activity improved survival of septic mice with pulmonary inflammation. Doxycycline was well tolerated at 100 mg twice a day during 10 days (for post-exposure prophylaxis of anthrax) or at the dose of 100 mg/day during several months (for malaria prophylaxis). In combination with chloroquine, this treatment would have shown a preventive effect in limiting the entry of SARS-CoV-1 into cells (not the current coronavirus).
Takeaways
These results must be confirmed by in vivo studies in humans on both the efficacy and safety of the treatment.
Strength of evidence Weak
- Experimental in vitro study
- No comparison of efficacy with control cells or chloroquine treatment
- No quantification of decreased viral replication or cytokine production
- Very preliminary study.
Objectives
Method
Treatment with doxycycline versus chloroquine (control group).
Evaluation of cytotoxicity, effective concentration
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