Clinical pharmacology of tocilizumab for the treatment of systemic juvenile idiopathic arthritis.

Tocilizumab is a humanized anti-IL-6 receptor monoclonal antibody approved for the treatment of rheumatoid arthritis and systemic juvenile idiopathic arthritis. Biweekly doses of 8 mg/kg for patients who weigh ≥ 30 kg and 12 mg/kg for patients who weigh <30 kg produce adequate blockade of IL-6 receptors and normalization of C-reactive protein levels. The mean area under the curve during a 2-week dosing interval, maximum and minimum serum concentrations for both doses were 1341 ± 415 µg·day/ml, 245 ± 57.2 and 57.5 ± 23.3 µg/ml, respectively. Tocilizumab pharmacokinetic exposure parameters and clinical end points were comparable between these two dose groups. Proportions of patients achieving clinical end points were comparable across exposure quartiles, suggesting that pharmacokinetic exposures are within the plateau of the exposure-response curve.