Advances in the Clinical Use of Hydroxychloroquine Levels

Katherine Chakrabarti; W. Joseph McCune

Disclosures

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

In This Article

What Hydroxychloroquine Level do we Target?

A target therapeutic hydroxychloroquine level is not established in part as there is also no current standardization of hydroxychloroquine levels across various labs. Numerous studies have suggested levels of 500–1000 ng/ml as a therapeutic target.[12]

In particular, several studies have focused levels needed for the prevention of lupus flares. In the PLUS study, a randomized control trial to evaluate the effects of targeting a hydroxychloroquine level at least 1000 ng/ml on the incidence of systemic lupus erythematosus (SLE) flares, increasing the dose of hydroxychloroquine to achieve levels at least 1000 ng/ml did not decrease the number of SLE flares over 7 months of follow-up. However, adherence increased in the control group and only 39% of the treatment group stayed above the 1000 ng/ml goal threshold.[16] Conversely, in two retrospective observational studies, Cunha et al.[17] reported that a hydroxychloroquine level greater than 600 ng/ml was associated with decreased likelihood of renal flares in patients with lupus nephritis, and Pedrosa et al.[18] reported that persistently low hydroxychloroquine levels less than 613.5 ng/ml best predicted risk of flares in 82 patients with lupus nephritis.

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