Therapeutic drug monitoring in inflammatory bowel disease patients switching from intravenous to subcutaneous infliximab: insights from a prospective real-world study
Year: 2026
Type: article
Abstract: BACKGROUND AND AIMS: The efficacy and safety of switching from intravenous (IV) to subcutaneous (SC) infliximab (IFX) have been demonstrated across multiple studies, but data on patients treated with high IV doses remain limited. This study aimed to confirm the safety of switching regardless of IV dosing regimen and examine serum drug concentrations during follow-up. METHODS: This prospective single-centre study included adult patients with inflammatory bowel disease in remission on maintenance IV IFX. Patients receiving IV IFX <1.5 mg/kg/week were assigned to 120 mg every 14 days, while those on ≥1.5 mg/kg/week received 240 mg. The target SC IFX serum range was 15-30 mg/L, with doses adjusted accordingly during follow-up. RESULTS: Among 267 patients, 93% were switched to standard SC dose and 7% to high dose. Remission rates remained stable over 6 months in both groups. Mean serum levels increased from 9.4 mg/L (IV) to 21.1 mg/L (SC) in the standard-dose group, and from 12.3 mg/L to 24.3 mg/L in the high-dose group. Serum IFX levels did not differ significantly by biochemical remission status. In multivariable linear regression, higher body mass index and previous intra-abdominal surgery were associated with lower serum IFX concentrations. CONCLUSION: Patients on IV IFX can be safely switched to SC treatment when initial dosing is guided by the prior IV regimen and subsequently individualized based on serum drug concentrations. Fixed SC dosing based solely on previous IV dosing may be appropriate for patients on standard IV doses but less reliable in those treated with higher doses.
Institutions: Oslo University Hospital, University of Oslo
Language: English
Topic: Inflammatory Bowel Disease
Subfield: Genetics
Domain: Life Sciences
Open Access status: hybrid
Funder: Oslo universitetssykehus HF
OpenAlex ID: W7142223942