Combining mepacrine with hydroxychloroquine-based therapy in active systemic lupus erythematosus: an observational...

To evaluate the efficacy of mepacrine (MC) as an add-on therapy in patients with SLE unresponsive to hydroxychloroquine (HCQ)-containing regimens at 6 months after MC introduction.

Observational study using routine clinical care data of patients from the Lupus-Cruces cohort. All of them received therapy with HCQ and prednisone at baseline. Two groups of initial therapy were compared: single therapy (ST; HCQ + prednisone) and multiple therapy (MT; additional immunosuppressives or biologics). Achieving the definition of remission in SLE (DORIS) at 6 months was the main outcome. Prednisone tapering and MC side effects and discontinuation were also analysed. A logistic regression was performed in search of clinical predictors of response.

106 different episodes were included (ST=56, MT=50). The mean SLE Disease Activity Index (SLEDAI) at baseline was 6.7, with a mean prednisone dose of 6 mg/day. DORIS remission at 6 months was 71% for the complete cohort (ST 79% vs MT 62%, p=0.06). SLEDAI reduction at 6 months was similar in both groups (mean 4.6 points in the ST group vs 5 in the MT group, p=0.5). The reduction at 6 months was also similar (mean 1.75 mg/day in the ST group vs 1.69 mg/day in the MT group, p=0.9). The most frequent reason for MC discontinuation was improvement (45%). Adverse effects were reported in 17% patients.

MC is a useful therapy in mild-moderate active SLE. Using MC as the first drug after the failure of glucocorticoids and HCQ is the best option; however, the addition of MC to a multidrug regimen can also be of help.