Pharmacodynamic monitoring by residual gene expression of the nuclear factor of activated T cell-regulated genes in lung transplant recipients and its correlation with tacrolimus blood levels.

Introduction: Trough blood levels (C0) of tacrolimus are used to adjust drug dosage, but they do not consistently correlate with clinical outcomes. Measurement of residual gene expression of nuclear factor of activated T cell (NFAT)-regulated genes (NFAT-RGE) has been proposed as a pharmacodynamic biomarker to assess the degree of immunosuppression in certain solid organ transplantations, but little is known regarding lung transplant recipients (LTR). Our primary objective is to correlate tacrolimus blood levels with NFAT-RGE. Methods: NFAT-RGE and tacrolimus C0 and peak (C1.5) levels were determined in 42 patients at three, six and 12 months post-transplantation. Results: Tacrolimus C0 did not exhibit a correlation with NFAT-RGE, whereas C1.5 did. Besides, over 20% of measurements indicated high levels of immunosuppression based on the below 30% NFAT-RGE threshold observed in many studies. Among those measurements within the therapeutic range, 19% had an NFAT-RGE<30%. Conclusion: Consequently, a subset of patients within the tacrolimus therapeutic range may be more susceptible to infection or cancer, potentially benefiting from NFAT-RGE and tacrolimus peak level monitoring to tailor their dosage. Further quantitative risk assessment studies are needed to elucidate the relationship between NFAT-RGE and the risk of infection, cancer, or rejection.

Isavuconazole use and TDM in real-world pediatric practice.

Isavuconazole (ISA) is approved for treating invasive aspergillosis and mucormycosis in adults, but its use in children remains off-label. We report on the use of ISA in real-world pediatric practice with 15 patients receiving ISA for treatment of invasive fungal infections. Therapeutic drug monitoring (TDM) was performed in all patients, with 52/111 (46.8%) Ctrough determinations out of range, thus supporting the need for TDM in children, especially those receiving extracorporeal membrane oxygenation (ECMO).

Ertapenem blood concentration: A retrospective cohort study to analyse risk of neurotoxicity.

AIMS: Several cases of ertapenem-related neurotoxicity have been published in the current literature. However, studies evaluating the ertapenem blood concentration (EBC) as a risk of these adverse events are scarce. We aimed to evaluate the relationship between the trough EBC and the risk of neurological toxicity. METHODS: This was a retrospective study, including patients who underwent ertapenem treatment between October 2019 and February 2021. We excluded patients in the critical care unit and those whose blood samples were not properly taken in order to analyse ertapenem trough concentration. We also excluded patients whose clinical follow-up was not properly realized for the entire period of ertapenem treatment. The main outcome was the presence of any suspicious neurological side effect owing to ertapenem administration and its relationship with the plasma concentration. Secondary outcomes were to identify clinical and analytical data contributing to a higher risk of neurotoxicity. RESULTS: The initial cohort comprised 158 individuals. For the final analysis we evaluated 102 patients, reporting a neurological alteration in 13/102 (12.7%). Mean trough EBC was significantly higher in patients showing neurotoxicity in comparison with those who did not (37.8 mcg mL-1 , standard deviation [SD] ± 35.7 vs. 14.6 mcg mL-1 , SD ± 15.2; P = .002). In multivariable logistic regression analysis, EBC (odds ratio [OR] = 1.07; P = .006), a moderate renal insufficiency (OR = 9.2; P = .02) and a history of previous neurologic disease (OR = 9.9; P = .02) were identified as risk factors of neurological alteration during ertapenem treatment. CONCLUSIONS: In patients at risk, determining the ertapenem plasma concentration may help to minimize the risk of neurotoxicity.

Rapid and accurate method for quantifying busulfan in plasma samples by isocratic liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Objectives: Administration of busulfan is extending rapidly as a part of a conditioning regimen in patients undergoing hematopoietic stem cell transplantation (HSCT). Monitoring blood plasma levels of busulfan is recommended for identifying the optimal dose in patients and for minimizing toxicity. The aim of this research was to validate a simple, rapid, and cost-effective analytical tool for measuring busulfan in human plasma that would be suitable for routine clinical use. This novel tool was based on liquid chromatography coupled to mass spectrometry. Methods: Human plasma samples were prepared using a one-step protein precipitation protocol. These samples were then resolved by isocratic elution in a C18 column. The mobile phase consisted 2 mM ammonium acetate and 0.1% formic acid dissolved in a 30:70 ratio of methanol/water. Busulfan-d8 was used as the internal standard. Results: The run time was optimized at 1.6 min. Standard curves were linear from 0.03 to 5 mg/L. The coefficient of variation (%CV) was less than 8%. The accuracy of this method had an acceptable bias that fell within 85-115% range. No interference between busulfan and the interfering compound hemoglobin, lipemia, or bilirubin not even at the highest concentrations of compound was tested. Neither carryover nor matrix effects were observed using this method. The area under the plasma drug concentration-time curves obtained for 15 pediatric patients who received busulfan therapy prior to HSCT were analyzed and correlated properly with the administered doses. Conclusions: This method was successfully validated and was found to be robust enough for therapeutic drug monitoring in a clinical setting.

Voriconazole Use in Children: Therapeutic Drug Monitoring and Control of Inflammation as Key Points for Optimal Treatment.

Voriconazole plasma concentrations (PC) are highly variable, particularly in children. Dose recommendations in 2-12-year-old patients changed in 2012. Little data on therapeutic drug monitoring (TDM) after these new recommendations are available. We aimed to evaluate voriconazole monitoring in children with invasive fungal infection (IFI) after implementation of new dosages and its relationship with safety and effectiveness. A prospective, observational study, including children aged 2-12 years, was conducted. TDM was performed weekly and doses were changed according to an in-house protocol. Effectiveness, adverse events, and factors influencing PC were analysed. A total of 229 PC from 28 IFI episodes were obtained. New dosing led to a higher rate of adequate PC compared to previous studies; still, 35.8% were outside the therapeutic range. In patients aged < 8 years, doses to achieve therapeutic levels were higher than recommended. Severe hypoalbuminemia and markedly elevated C-reactive protein were related to inadequate PC. Therapeutic PC were associated with drug effectiveness and safety. Higher doses in younger patients and a dose adjustment protocol based on TDM should be considered. Voriconazole PC variability has decreased with current updated recommendations, but it remains high and is influenced by inflammatory status. Additional efforts to control inflammation in children with IFI should be encouraged.