February 22, 2013
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No reduction observed in lupus flares following hydroxychloroquine adjustment

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Adjusting hydroxychloroquine dosages failed to reduce the rate of lupus flares despite the association between lower blood hydroxychloroquine levels and increased systemic lupus erythematosus activity, according to study results.

In a prospective, double blind, placebo-controlled, multicenter trial, researchers in France evaluated 573 patients (mean age, 39 years; 92% women) with systemic lupus erythematosus (SLE) who had been treated with hydroxychloroquine (HCQ) for a median of 6.7 years. Patients had a median disease duration of 8 years, and 12% had active SLE.

One hundred seventy-one of the patients whose HCQ blood concentrations were between 100 ng/mL and 750 ng/mL were randomly divided into two groups. Daily HCQ dose remained the same for group 1 (n=84; mean age, 41 years; 86% women), while group 2 (n=87; mean age, 38 years, 89% women) received an increased dose to achieve target blood HCQ levels of at least 1,000 ng/mL. Number of patients with flares during the 7-month follow-up was the primary end point.

SLE flare rates were similar between groups: 25% in Group 1 and 27.6% in Group 2 (P=.7). Improved treatment adherence, however, was suggested by a significant spontaneous increase in HCQ blood concentration in both groups between study inclusion and randomization (P=.0001). Patients who were treated at the therapeutic target of HCQ blood levels of 1,000 ng/mL or more during follow-up tended to have fewer flares (20.5%) compared with those with lower HCQ blood concentrations (35.1%; P=.12).

“This study confirms the [pharmacokinetic/pharmacodynamic] relation for HCQ in patients with SLE,” the researchers concluded. “Our results do not justify recommending a therapeutic adaptation of HCQ dose to [HCQ blood concentration]. However, we suggest that [HCQ blood concentration] be measured to detect nonadherence, especially in patients with active disease, and to help patients with poor adherence reach [the HCQ blood concentration target of at least] 1,000 ng/mL.”