Hydroxychloroquine blood concentrations and effects in Chinese patients with IgA nephropathy

Abstract Background Hydroxychloroquine (HCQ) is recommended for Chinese patients with immunoglobulin A nephropathy (IgAN). However, the relationship between HCQ blood concentration and the therapeutic effect for IgAN has not yet been defined. This study investigates the optimal and efficacious range of HCQ blood concentrations in Chinese patients with IgAN. Methods Seventy-three patients with biopsy-proven IgAN who were at risk of progression were included in this study. Thirty-eight patients with IgAN were treated with HCQ plus an optimized renin–angiotensin–aldosterone system inhibitor (RAASi), and thirty-five patients received only RAASi. Blood HCQ concentration and 24-h proteinuria were examined at three and six months after treatment. Results The baseline proteinuria levels were comparable between the RAASi and HCQ groups. The HCQ group had lower 24-h proteinuria than the RAASi group three months after treatment, though the difference was not significant ( p = 0.38). After six months, the median proteinuria level was significantly lower in the HCQ group than in the RAASi group ( p < 0.05). The percentage reduction in 24-h proteinuria in the HCQ group was greater than that in the RAASi group at three ( p < 0.05) and six months ( p < 0.05). Hydroxychlorquine blood concentration and efficacy were positively correlated at three months ( r = 0.428, p < 0.05) and six months ( r = 0.48, p < 0.05). Moreover, the optimal blood concentration of HCQ for three-month efficacy was 418.96 ng/mL and that for six-month efficacy was 582.48 ng/mL. No serious adverse events were reported during HCQ treatment. Conclusions Hydroxyhloroquine safely reduces proteinuria in Chinese patients with IgAN. The efficacy of HCQ is positively correlated with its blood concentration. Graphical abstract