Advances in the Clinical Use of Hydroxychloroquine Levels

Katherine Chakrabarti; W. Joseph McCune


Curr Opin Rheumatol. 2022;34(3):151-157. 

In This Article

Appropriate Timing of Hydroxychloroquine Levels

Because of the long half-life of hydroxychloroquine, it was initially thought that measurement of the level at any point after several months of use was valid. Al-Rawi et al. (2018), however, demonstrated that even after 6 months, whole blood levels of hydroxychloroquine measured at seven timepoints over a 12-h period varied for the same patient by 27%. Maximum levels occurred 2–6 h after administration. Knowing the time since the preceding hydroxychloroquine dose is important to properly interpret hydroxychloroquine levels, particularly when values are at the extremes of expected values.[6] Alternating daily doses, for example, alternating 400 mg with 200 mg every other day to achieve a mean daily dose of 300 mg, reduces accuracy of assessment.