No reduction observed in lupus flares following hydroxychloroquine adjustment
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.”