4.2 Chloroquine alone for the treatment of COVID-19 infection
The initial once-daily dose of 250 mg chloroquine provided adequate
plasma concentration-time profiles to achieve the therapeutic effect
(EC50) for COVID-19 on day 7. Nevertheless, the unbound
Ctrough at 24 hours was not sufficient to exert
inhibitory effect (EC50) on the virus. This regimen is,
therefore, not appropriate for the treatment of COVID-19 infection. This
finding is in accordance with that was reported by Wang and
colleagues6, of which the EC50 could
not be achieved with the drug concentration delivered following the
once-daily dose regimen of 250 mg chloroquine (for 28 days) in
rheumatoid patients. Simulation of chloroquine 500 mg once-daily dose
also did not provide adequate the unbound Ctrough at 24
hours to exert inhibitory effect (EC50) on the virus.
This finding is in contrast with Wang and colleagues’ proposal that the
concentration achieved following the once-daily dose regimen of 500 mg
chloroquine could be sufficient to inhibit the entry of the virus into
host cells (Wang et al., 2020). This could be due to the fact that the
reported 500 mg-plasma concentration profiles were not actual observed
clinical data, but the extrapolation from the once-daily dose regimen of
250 mg in rheumatoid patients.