Intra‐patient variability in adalimumab drug levels within and between cycles in Crohn's disease

• DOI: 10.1111/apt.13992
• Publication Date: 2017-02-27T05:52:58Z
• Authors: M. G. Ward; P. A. Thwaites; L. Beswick; J. Hogg; G. Rosella; D. Van Langenberg; J. Reynolds; P. R. Gibson; M. P. Sparrow
• Keywords: Crohn disease

Whether therapeutic drug monitoring for adalimumab needs to be performed at trough has not been defined.To determine intra-patient drug-level variation and identify modulating patient disease factors.In this prospective observational study, adult patients with Crohn's established on maintenance had levels measured repeatedly according pre-defined schedules (visit 1: day 4-6, visit 2: 7-9, trough: 13-14) across two consecutive fortnightly cycles. Disease activity was assessed using Harvey-Bradshaw Index, C-reactive protein faecal calprotectin. For analysis, ≥4.9 μg/mL were considered therapeutic.Nineteen underwent 111 evaluations. Mean from paired visits between cycles did differ (visit1 cycle1: 4.81, cycle2: 5.21 μg/mL, P = 0.24, visit2 4.86, 4.82, 0.91 3.95, 0.99), irrespective of activity. Drug stable over the first 9 days 1-2), but declined by a mean 1.06 0.89 1 or 2, respectively (P < 0.001). Models nontemporal factors (smoking, syringe delivery device) earlier accounted 66-80% variance in levels. On receiver-operating curve thresholds identified that predicted level similar threshold itself, high sensitivity modest specificity.While should trough, obtained during predicts reasonable confidence.