Aims
Therapeutic drug monitoring of infliximab can guide clinical decisions in patients with loss of response and in those who can benefit from a de‐intensification. The aim of this study was to determine the impact of therapeutic drug monitoring combined with Bayesian forecasting methodology on clinical response in a real‐world dataset of patients suffering from inflammatory bowel disease.
Methods
We performed a single‐centre prospective study with one‐group pre‐test/post‐test design in 108 adult inflammatory bowel disease patients treated with model‐based dosing of infliximab maintenance treatment. We recorded clinical activity scores (Harvey‐Bradshaw index and partial Mayo) and inflammatory biomarkers per patient.
Results
The initial infliximab regimen was maintained in 49 (45.4%) patients and was adjusted in 59 (54.6%) patients (34 treatment intensifications, 9 de‐intensifications and 16 treatment discontinuations or therapy replacements). The median time from intervention to index measurement was 126 (103–160) days. The overall proportion of patients in clinical remission increased from 65.7% to 80.4% (P < .0001) and the median infliximab trough concentrations increased from 3.21 (0.99–5.45) to 5.13 mg/L (3.57–6.53) (P < .0001). In the intensified group, the remission rate increased from 35.3% to 61.8% (P = .001) and the percentage of patients in clinical remission or with mild symptoms increased from 76.5% to 94.1%. In the de‐intensification cohort, no patients experienced an increase in the Harvey‐Bradshaw index or partial Mayo scores, and all patients maintained an infliximab trough concentration of >5 mg/L.
Conclusion
In our cohort of inflammatory bowel disease patients, Bayes‐based optimized dosing improved the short‐term efficacy of infliximab treatment.
Background
The pharmacokinetics (PK) of antibiotics change during sepsis and continuous renal replacement therapies in critically ill patients. Limited evidence exists on the use of the oXiris® high-adsorbent membrane.
Objectives
To develop a PK/pharmacodynamic (PD) model for meropenem in critically ill sepsis patients undergoing continuous venovenous haemodiafiltration (CVVHDF) with the oXiris® membrane, and to design an optimal dosing regimen assessed according to the PTA.
Methods
A prospective, open-label, observational PK trial was performed (EUDRACT 2011-005902-30). We conducted PK studies (plasma and ultrafiltrate) for at least 24 h after concomitant administration of CVVHDF and meropenem 1 g q8h. We constructed a PK model using the non-linear mixed-effects approach (NONMEM 7.3). We evaluated the suitability of different dosage regimens using Monte Carlo simulations and calculated the PTA as the percentage of subjects achieving a given percentage of time above the MIC (fT>MIC).
Results
The PK of meropenem was best captured by a two-open-compartment model with zero-order input kinetics and first-order elimination. Extracorporeal CL was 7.78 L/h [relative standard error (RSE) 16.45 L/h] and central compartment V (Vc) was 24.9 L (RSE 13.73 L). Simulations showed that, for susceptible Pseudomonas aeruginosa isolates (EUCAST MIC ≤2 mg/L) and attainment of 100%fT>MIC, 500 mg q8h given as extended (EI) or continuous infusion (CI) would be sufficient. For a target of 100%fT>4×MIC, CI of 3000 mg q24h or 2000 mg q8h administered as EI or CI would be required.
Conclusions
We have constructed a PK model of meropenem in sepsis patients undergoing CVVHDF using the oXiris® membrane. This tool will support physicians when calculating the optimal initial dose.
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