Placing nebulizers within a HFT circuit upstream from the humidification chamber may enable to deliver clinically relevant masses of aerosol at the cannula outlet, but more importantly downstream of the nose and pharynx, even in case of high patients' inspiratory flow. This method of aerosol therapy is expected to produce a bronchodilatatory effect to be evaluated in the clinical settings.

A high CV of TAC concentrations was found to be predictive of TAC-related toxicity and poorer survival.

Posaconazole is extensively used for prophylaxis for invasive fungal infections. The gastro-resistant tablet formulation has allowed the bioavailability issues encountered with the oral suspension to be overcome. However, overexposure is now frequent. This study aimed to (i) describe the pharmacokinetics of posaconazole tablets in a real-life cohort of patients with hematological malignancies and (ii) perform Monte Carlo simulations to assess the possibility that the daily dose can be reduced while keeping a sufficient exposure. Forty-nine consecutive inpatients were prospectively included in the study. Posaconazole trough concentrations (TC) were measured once a week, and biological and demographic data were collected. The concentrations were analyzed by compartmental modeling, and Monte Carlo simulations were performed using estimated parameters to assess the rate of attainment of the target TC after dose reduction. The pharmacokinetics of posaconazole were well described using a one-compartment model with first-order absorption and elimination. The values of the parameters (interindividual variabilities) were as follows: the absorption constant ( ) was 0.588 h (fixed), the volume of distribution (/) was 420 liters (28.2%), and clearance (CL/) was 7.3 liters/h (24.2%) with 31.9% interoccasion variability. Forty-nine percent of the simulated patients had TC at steady state of ≥1.5 μg/ml and maintained a TC above 1 μg/ml after a reduction of the dose to 200 mg daily. A third of these patients eligible for a dose reduction had TC of ≥1.5 μg/ml as soon as 48 h of treatment. Though posaconazole tablets were less impacted by bioavailability issues than the oral suspension, the pharmacokinetics of posaconazole tablets remain highly variable. Simulations showed that approximately half of the patients would benefit from a reduction of the dose from 300 mg to 200 mg while keeping the TC above the minimal recommended target of 0.7 μg/ml, resulting in a 33% savings in the cost of this very expensive drug.

Tacrolimus (TAC) is the cornerstone of immunosuppressive therapy in liver transplantation. This study aimed at elucidating the interplay between pharmacogenetic determinants of TAC whole blood and intracellular exposures as well as the pharmacokinetic-pharmacodynamic relationship of TAC in both compartments. Complete pharmacokinetic profiles (Predose, and 20 min, 40 min, 1h, 2h, 3h, 4h, 6h, 8h, 12h post drug intake) of twice daily TAC in whole blood and peripheral blood mononuclear cells (PBMC) were collected in 32 liver transplanted patients in the first ten days post transplantation. A non-parametric population pharmacokinetic model was applied to explore TAC pharmacokinetics in blood and PBMC. Concurrently, calcineurin activity was measured in PBMC. Influence of donor and recipient genetic polymorphisms of ABCB1, CYP3A4 and CYP3A5 on TAC exposure was assessed. Recipient ABCB1 polymorphisms 1199G>A could influence TAC whole blood and intracellular exposure (p<0.05). No association was found between CYP3A4 or CYP3A5 genotypes and TAC whole blood or intracellular concentrations. Finally, intra-PBMC calcineurin activity appeared incompletely inhibited by TAC and less than 50% of patients were expected to achieve intracellular IC 50 concentration (100 pg/millions of cells) at therapeutic whole blood concentration (i.e.: 4-10 ng/mL). Together, these data suggest that personalized medicine regarding TAC therapy might be optimized by ABCB1 pharmacogenetic biomarkers and by monitoring intracellular concentration whereas the relationship between intracellular TAC exposure and pharmacodynamics biomarkers more specific than calcineurin activity should be further investigated.

This study aimed at exploring the link among individual concentrations, pharmacokinetic parameters, and the probability of relapse after de‐escalation in a real‐world prospective cohort of patients with inflammatory bowel disease (IBD) who underwent infliximab treatment de‐escalation. Ninety‐one patients were included. A time‐varying compartment model was used to estimate individual pharmacokinetic parameters and trough concentrations. A Cox model was implemented to explore the parameters influencing the probability of relapse after de‐escalation. Volume, clearance, and trough before and after de‐escalation were linked to the relapse risk at the univariate step. Independent predictors of relapse were tobacco use and/or ulcerative colitis (P = 0.0093), a higher C‐reactive protein (CRP; P = 0.00064), and an infliximab trough < 2.4 μg/mL after de‐escalation (P = 0.0001). Patients with trough > 5.7 μg/mL are eligible to de‐escalation, but infliximab pharmacokinetics is highly variable in time. Therefore, drug monitoring is mandatory after de‐escalation to maintain trough > 2.4 μg/mL. Clearance monitoring seems an appealing approach for patient selection and relapse prediction.

SummaryBackgroundThere are limited data concerning infliximab drug monitoring during de‐escalation of the treatment of inflammatory bowel disease (IBD).AimTo define the rate and the predictors of relapse following infliximab de‐escalation in IBD patients in remission.MethodsAll IBD patients at a single referral centre in clinical and biological remission and in whom the dose of infliximab had been de‐escalated were included. Patients in remission with a high trough level of infliximab (>7 mg/L) were considered to be trough level‐based de‐escalation patients. The data were retrieved from a prospective IBD database. Actuarial analysis was performed for statistical purposes.ResultsA total of 146 de‐escalations were performed in 96 patients (Crohn's disease/ulcerative colitis: 68%/32%); 54 (37%) were based on clinical remission only, and 92 (63%) were based on clinical remission associated with a trough level above 7 mg/L. The cumulative probabilities of relapse following infliximab de‐escalation were 16% and 47% at 1 and 2 years, respectively. Ulcerative colitis was associated with an increased risk of relapse (HR = 3.2, P = 0.005). Conversely, combination therapy at infliximab initiation (HR = 0.39, P = 0.0110) and trough level‐based de‐escalation were associated with decreased risk of relapse (HR = 0.45, P = 0.024). Trough levels before and after de‐escalation were well correlated; a decrease by half was observed following a 2‐week interval increase or a half‐dose decrease.ConclusionThe use of trough levels to assess the feasibility of dose de‐escalation seems to be a prerequisite for decreasing the risk of relapse.

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Posaconazole was well tolerated; however, LFT abnormalities were frequent. ADR occurrence was not linked to posaconazole exposure. Because posaconazole concentrations were highly variable, TDM can be helpful to avoid underexposure to the drug and increase its efficacy in preventing IFI. Conversely, a large proportion of patients was overexposed and might have benefited of a dose reduction.