Hydroxychloroquine and azithromycin as potential treatments for COVID-19; clinical status impacts the outcome
Okour et al.
, Hydroxychloroquine and azithromycin as potential treatments for COVID-19; clinical status impacts the outcome
, Journal of Pharmacokinetics and Pharmacodynamics, May 13, 2020, doi:10.1007/s10928-020-09689-x
Odds of PCR-positive decrease by 53% for each unit increase in HCQ log-concentration. Similarly, the odds decrease by 61%, and by 12% for each day increase, and for azithromycin co-treatment, respectively. Computes the minimum HCQ concentration needed based on severity, and corresponding dosage regimens. A loading dose is found to be important. For LRTI and URTI patients the addition of AZ is needed. Extended analysis of Gautret et al. using the observed HCQ concentrations and pharmacokinetic analysis to compute concentrations for all days.
Okour et al., 13 May 2020, peer-reviewed, 3 authors.
Abstract: Journal of Pharmacokinetics and Pharmacodynamics
Hydroxychloroquine and azithromycin as potential treatments
for COVID-19; clinical status impacts the outcome
Mahmoud Al-Kofahi2 • Daren Austin3
Received: 27 April 2020 / Accepted: 4 May 2020
Ó Springer Science+Business Media, LLC, part of Springer Nature 2020
In March 2020, hydroxychloroquine (HCQ) and azithromycin were tested as potential treatments for COVID19 pandemic, in an open label non-randomized clinical trial
. Data were collected from 36 confirmed COVID-19
patients after receiving no treatment (n = 16) or 200 mg
q8h of HCQ with (n = 6) or without (n = 14) azithromycin
depending on clinical status. Collected data over six days
included one HCQ concentration per patient; respiratory
viral loads (PCR assay); azithromycin co-treatment; and
clinical status among other variables.
Using observed HCQ concentrations and basic pharmacokinetic equations, it was possible to calculate missing
concentrations at all days for all patients (Supplementary
Fig. S1). Daily viral load, presented as PCR threshold cycle
(CT), was converted into a dichotomous variable (positivePCR or negative-PCR). A logistic regression evaluated
whether HCQ concentrations, azithromycin co-treatment
(yes/no), clinical status (asymptomatic, upper or lower
respiratory tract infection [URTI or LRTI]), time (day
0–6), and other covariates (age, sex) were associated with
response (positive-PCR outcome).
Electronic supplementary material The online version of this
contains supplementary material, which is available to
& Malek Okour
GlaxoSmithKline, Collegeville, PA, USA
College of Pharmacy, University of Minnesota, Minneapolis,
GlaxoSmithKline, London, UK
Model evaluation and selection was performed based on
statistical significance (p-value B 0.05) and diagnostic
plots (Supplementary Figs. S2, S3). The final model contained HCQ log-concentrations (ng/ml), azithromycin cotreatment, clinical status, and day as statistically significant
covariates (Figs. 1 and S4).
Results showed that the odds of positive-PCR decrease
by 53% for each unit increase in HCQ log-concentration.
Similarly, the odds decrease by 61%, and by 12% for each
day increase, and for azithromycin co-treatment, respectively. Whereas the odds of positive-PCR increase by 99.4
folds and 212 folds for having URTI and LRTI versus
being asymptomatic subject.
Using the model, minimum HCQ concentrations to
achieve [ 50% probability of negative-PCR on day 3 were
calculated, with or without azithromycin, for the clinical
statuses. A minimum HCQ concentration (ng/ml) of 8103
(without azithromycin) and 282 (with azithromycin) are
needed in subjects with LRTI. A minimum HCQ concentration (ng/ml) of 2441 (without azithromycin) and 83.9
(with azithromycin) are needed in subjects with URTI.
Asymptomatic patients require minimal HCQ concentrations (\ 2 ng/ml) regardless of azithromycin co-treatment.
Next, HCQ population PK model  was used to simulate dosing regimens needed to achieve targeted HCQ
concentrations. Simulations showed that when HCQ is coadministered with azithromycin, a loading dose is critical
in rapid achievement of targeted concentrations. The suggested..
is less effective
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