Hydroxychloroquine at usual doses as an option for coronavirus disease 2019 treatment

To the Editors:

We read with great interest the article by Dashraath et al.¹ During pregnancy, the onset of severe acute respiratory syndrome (SARS) can jeopardize both mother and fetus and may cause extreme prematurity, as in previous coronavirus outbreaks.

Considering the promising chloroquine treatment, the authors focus on the side effects of high doses, mainly on the basis of the report of higher volumes of distribution of chloroquine during pregnancy in a small series of women.² However, their deduction of an assumed need for higher doses against coronavirus disease 2019 (“at least 500 mg twice daily”) raises the question of the rationale for such doses.

In actuality, the authors of this pharmacokinetic study² only hypothesized that reduced concentrations of chloroquine in pregnancy “could compromise its curative antimalarial efficacy.”

Besides, the 90% effective inhibitor concentration of chloroquine against SARS coronavirus 2 in Vero E6 cells is low³ and easily achievable in vivo. Another pharmacokinetic study confirms that clearance and total drug exposure of the widely used variant hydroxychloroquine does not change during pregnancy,⁴ which does not support using higher doses during pregnancy.^{4 , 5}