Background and Importance Failure of biologic therapy (anti-tumour necrosis factor (TNF) drugs) is a common problem. Pharmacokinetic monitoring can contribute to early identification of therapeutic failure and thus optimise treatment by keeping drug concentrations within the therapeutic interval (TI) where the probability of efficacy is higher and the likelihood of toxicity and development of immunogenicity is minimal.

Aim and Objectives To assess the acceptability of pharmacokinetic recommendations for adalimumab (ADA) and infliximab (IFX) in clinical practice in patients with inflammatory bowel disease (IBD).

Material and Methods Retrospective observational study (June 2023 – September 2023) in patients with IBD treated with anti-TNF drugs. All patients who were requested for ADA or IFX plasma levels were included.

Variables sex, age, type of pathology (Crohn’s disease (CD) or Ulcerative Colitis (UC)), anti-TNF regimen, concomitant immunomodulators, type of recommendation (maintenance of regimen, optimisation, intensification) and acceptance of recommendations. The therapeutic interval (TI) was 3–10 mcg/ml (IFX) and 5–12 mcg/ml (ADA).

Data source electronic health record (Mambrino XXI®) and MwPharm++ pharmacokinetic monitoring software.

Results Seventy-two patients (65% male) were included, with a median age of 47 (16–77) years. Of these, 75% had CD and 25% had UC. 53 patients were on ADA and 19 on IFX. Seventy-eight pharmacokinetic monitoring tests were performed. 60% were within the TI, 21% were subtherapeutic and 19% were supratherapeutic. In 3 patients, the concentration was higher than the TI and was not in accordance with the previous ones, so a new control was requested. After this, it was confirmed that they were within the TI and maintenance of the regimen was recommended.

The pharmacokinetic recommendations conducted were maintenance of regimen (73%), intensification (17%) and optimisation (10%). 94% of recommendations were accepted. The recommendations that were not accepted (6%) were due to clinical worsening of the patient and a change of therapeutic target was made.

Conclusion and Relevance Based on the results of our study, the degree of acceptance of pharmacokinetic recommendations was high (94%). Pharmacokinetic monitoring is an important element of support in clinical decision making. Through this practice, the hospital pharmacist contributes to the optimisation of these treatments, helping to ensure that the appropriate adjustment is made for a better response.

Conflict of Interest No conflict of interest.