• adalimumab;
  • infliximab;
  • Psoriasis Area and Severity Index;
  • psoriasis;
  • trough


We examined the relation between adalimumab and infliximab plasma trough levels, anti-adalimumab and anti-infliximab antibody formation. We analyzed plasma from 32 adalimumab-treated and 20 infliximab-treated psoriasis patients for evaluating trough levels of each drug. The presence of anti-adalimumab and anti-infliximab antibodies was analyzed and the severity of psoriasis was evaluated. At week 28, 25 out of 32 and at week 48, 21 out of 30 adalimumab-treated patients maintained as more than PASI 75. At week 28, 12 out of 20 and at week 48, nine out of 18 infliximab-treated patients were evaluated as more than PASI 75. In patients treated with 40 mg adalimumab every other week, the mean trough level was 7.62 μg/mL (range, 0.05–10.6) at week 48. In patients treated with 80 mg adalimumab every other week, the mean trough level was 8.61 μg/mL (range, 0.08–13.5) at week 48. Mean trough level of infliximab-treated cases (4.1–5.2 mg/kg; mean, 4.6) was 4.64 μg/mL (range, 0.03–16.9) at week 48. Anti-adalimumab antibody was detected in five out of 32 cases and anti-infliximab antibody was detected in six out of 20 cases, respectively, at weeks 24 and 48. The optimal cut-off values of adalimumab and infliximab concentration for more than PASI 75 were more than 7.84 μg/mL and more than 0.92 μg/mL, respectively. The trough levels of adalimumab and infliximab in psoriasis patients were positively associated with clinical response and were significantly lower in cases having anti-adalimumab or anti-infliximab antibodies.