Figure 3: Hydroxychloroquine drug concentrations.

Right-side axes indicate extrapolated plasma concentrations assuming blood to plasma ratio of 7.2 and hydroxychloroquine molecular weight of 336 g/mol.(16) Panel A shows trough drug concentrations in participants taking once weekly compared with twice weekly hydroxychloroquine. All participants had detectable hydroxychloroquine in whole blood samples. Panel B depicts drug concentrations in participants from both hydroxychloroquine arms with and without Covid-19 compatible illness. Participants with Covid-19 compatible illness had median concentrations of 154 ng/mL compared with 133 ng/mL among those without symptomatic Covid-19 compatible illness (P=0.08). Red dashed line indicates extrapolated EC50 target assuming blood to plasma ratio of 7.2, target EC50 of 0.7μm = 235 ng/mL plasma = 1690 ng/mL whole blood.(5)