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The Norwegian study for therapeutic drug monitoring

Project managers
Post doc
PhD fellow


Biological drugs, including infliximab, have revolutionized the treatment of a number of chronic inflammatory immunological diseases, but a proportion of patients do not reach the goal of remission and many patients lose their effectiveness over time. There are large individual differences in the drug concentration in the blood in patients on the standard dose, with a large proportion of patients both without a measurable level and with levels well above the assumed therapeutic level. One of the reasons for low levels is the development of antibodies against infliximab. Underdosing in the form of low serum concentrations is related to a poorer treatment effect, while overdosing can increase the risk of side effects and result in unnecessarily high societal costs. There was therefore reason to believe that target management of infliximab treatment according to serum concentration and measurements of drug antibodies will bring more patients into remission and prevent disease flare-ups during treatment. However, there was a lack of effect studies in this area. Therapeutic drug monitoring of infliximab treatment had therefore not been widely implemented either nationally or internationally.

In this study, we wanted to investigate whether targeting infliximab treatment using regular measurements of serum concentration and antibodies would improve disease control in patients starting treatment with infliximab (part A) and in patients on maintenance treatment (part B).

We expected that NOR-DRUM could have a major impact on the treatment and follow-up of patients with inflammatory immunological diseases in both the short and long term.


Adults with ulcerative colitis, Crohn's disease, rheumatoid arthritis, spondyloarthritis, psoriatic arthritis and psoriasis who are to start treatment with infliximab.

Recruitment of participants has ended.


The study has now ended.

NOR-DRUM A and NOR-DRUM B are randomized controlled studies. The patients in the intervention group received infliximab based on a treatment strategy based on regular measurements of serum concentration and drug antibody, while the control group received the standard infliximab dose.

In NOR-DRUM A, 400 patients were included. The effect of the intervention was measured in the proportion of patients who went into remission after 30 weeks (defined on the basis of validated disease activity measures for each disease).

In NOR-DRUM B, 500 patients were included and the effect was measured in the proportion that did not develop a disease flare during 52 weeks.

The patients in NOR-DRUM A and B were followed at each infusion with, among other things, recording of patient-reported outcome measures, validated disease activity measures for the various diseases and side effects. Blood samples were taken including biobank and serum concentration and antibodies.