Background Acute severe ulcerative colitis (ASUC), the most aggressive presentation ulcerative colitis (UC), occurs in 15 percent of adults and children with UC. First line therapy with intravenous corticosteroids is ineffective in half of adults and one third of children. Therapeutic monoclonal antibodies against TNF (anti-TNF therapy) are emerging as a common treatment for ASUC due to their similar efficacy to calcineurin inhibitors and more favorable adverse effect profile. Aim To comprehensively review the evidence for anti-TNF therapy for ASUC in children and adults with regard to outcomes and pharmacokinetics. Methods PubMed and recent conference proceedings were searched using the terms “ulcerative colitis”, “acute severe ulcerative colitis”, “anti-TNF”, “pharmacokinetics”, and the generic names of specific anti-TNF agents. Results Outcomes after anti-TNF therapy for ASUC remain suboptimal with aboutone half of children and adults undergoing colectomy. While several randomized controlled trials have demonstrated the efficacy of anti-TNF therapy for ambulatory patients with moderate to severely active UC, patients in these studies were less ill than those with ASUC. Patients with ASUC may exhibit more rapid clearance of anti-TNF biologics due pharmacokinetic mechanisms influenced by disease severity. Conclusions Conventional weight-based dosing effective in patients with moderately to severely active UC, may not be equally effective in those with ASUC. Personalized anti-TNF dosing strategies that integratepatient factors and early measures of pharmacokinetics and response hold promise for ensuring sustained drug exposure and maximizing early mucosal healing in patients with ASUC.

Background Many pediatric patients with inflammatory bowel disease (IBD) lose response to infliximab (IFX) within the first year, and achieving a minimal target IFX trough concentration is associated with higher remission rates and longer durability. Population pharmacokinetic (PK) modeling can predict trough concentrations for individualized dosing. The object of this study was to refine a population PK model that accurately predicts individual IFX exposure during maintenance therapy using longitudinal real-practice data. Methods We exported data from the electronic health records of pediatric patients with IBD treated with originator IFX at a single center between January 2011 and March 2017. Subjects were divided into discovery and validation cohorts. A population PK model was built and then validated. Results We identified 228 pediatric patients with IBD who received IFX and had at least 1 drug concentration measured, including 135 and 93 patients in the discovery and validation cohorts, respectively. Weight, albumin, antibodies to IFX (ATI) detected by a drug-tolerant assay, and erythrocyte sedimentation rate (ESR) were identified as covariates significantly associated with IFX clearance and incorporated into the model. The model exhibited high accuracy for predicting target IFX trough concentrations with an area under the receiver operating characteristic curve (AUROC) of 0.86 (95% confidence interval [CI], 0.81–0.91) for population-based predictions without prior drug-level input. Accuracy increased further for individual-based predictions when prior drug levels were known, with an AUROC of 0.93 (95% CI, 0.90–0.97). Conclusions A population PK model utilizing weight, albumin, ordinal drug-tolerant ATI, and ESR accurately predicts IFX trough concentrations during maintenance therapy in real-practice pediatric patients with IBD. This model, which incorporates dynamic clinical information, could be used for individualized dosing decisions to increase response durability.

PEG placement is both feasible and safe in small, medically complicated infants.