Impact of hypoalbuminemia on voriconazole pharmacokinetics in critically ill adult patients

Combined impact of hypoalbuminemia and pharmacogenomic variants on voriconazole trough concentration: data from a real-life clinical setting in the Chinese population

Voriconazole (VRC) displays highly variable pharmacokinetics impacting treatment efficacy and safety. To provide evidence for optimizing VRC therapy regimens, the authors set out to determine the factors impacting VRC steady-state trough concentration (Cmin) in patients with various albumin (Alb) level. A total of 275 blood samples of 120 patients and their clinical characteristics and genotypes of CYP2C19, CYP3A4, CYP3A5, CYP2C9, FMO3, ABCB1, POR, NR1I2 and NR1I3 were included in this study. Results of multivariate linear regression analysis demonstrated that C-reactive protein (CRP) and total bilirubin (T-Bil) were predictors of the VRC Cmin adjusted for dose in patients with hypoalbuminemia (Alb < 35 g/L) (R2 = 0.16, P < 0.001). Additionally, in patients with normal albumin level (Alb ≥ 35 g/L), it resulted in a significant model containing factors of the poor metabolizer (PM) CYP2C19 genotype and CRP level (R2 = 0.26, P < 0.001). Therefore, CRP and T-Bil levels ought to receive greater consideration than genetic factors in patients with hypoalbuminemia.

Population Pharmacokinetics of Voriconazole and Dose Optimization in Elderly Chinese Patients

Voriconazole is commonly recommended as a first-line therapy for invasive aspergillosis infections. Elderly patients are susceptible to infectious diseases owing to their decreased physical function and immune system. Our study aims to establish a population pharmacokinetics model for elderly patients receiving intravenous voriconazole, and to optimize dosing protocols through a simulated approach. An accurate fit to the concentration-time profile of voriconazole was achieved by employing a 1-compartment model featuring first-order elimination. The typical clearance rate of voriconazole was found to be 3.22 L/h, with a typical volume of distribution of 194 L. The covariate analysis revealed that albumin (ALB), gamma-glutamyl transpeptidase, and direct bilirubin had significant impacts on voriconazole clearance. Additionally, body weight was found to be associated with the volume of distribution. Individualized dosing regimens were recommended for different ALB levels based on population pharmacokinetics model prediction. The proposed dosing regimens could provide a rationale for dosage individualization, improve the clinical outcomes, and minimize drug-related toxicities.

The impact of extracorporeal membrane oxygenation on antifungal pharmacokinetics: A systematic review

BACKGROUND AND OBJECTIVE

The use of extracorporeal membrane oxygenation (ECMO) as a cardiocirculatory or respiratory support has tremendously increased in critically ill patients. In the setting of ECMO support, invasive fungal infections are a severe cause of morbidity and mortality. This vulnerable population is at risk of suboptimal antifungal exposure due to an increased volume of distribution (Vd), drug sequestration and decreased clearance. Here, we aimed to summarize ex-vivo and clinical studies on the potential impact of ECMO on the pharmacokinetics (PK) of antifungal agents and dosing requirements.

METHODS

A systematic search of the literature within electronic databases PubMed and EMBASE was conducted from database inception to 30 April 2023. Inclusion criteria were as follows: critically ill patients receiving ECMO regardless of age and reporting at least one PK parameter.

RESULTS

Thirty-six studies met inclusion criteria, including seven ex-vivo experiments and 29 clinical studies evaluating three classes of antifungals: polyenes, triazoles and echinocandins. Based on the available ex-vivo PK data, we found a significant sequestration of highly lipophilic and protein-bound antifungals within the ECMO circuit such as voriconazole, posaconazole and micafungin but the PK of several antifungals remains to be addressed such as amphotericin B, isavuconazole and anidulafungin. Most clinical studies have shown increased Vd of some antifungals like fluconazole and micafungin, particularly in the pediatric population. Conflicting data exist about caspofungin exposure.

CONCLUSIONS

The available literature on the antifungal PK changes in ECMO setting is scarce. Whenever possible, therapeutic drug monitoring is highly advised to personalize antifungal therapy.

Prediction of plasma trough concentration of voriconazole in adult patients using machine learning

OBJECTIVE

Plasma trough concentration of voriconazole (VCZ) was associated with its toxicity and efficacy. However, the nonlinear pharmacokinetic characteristics of VCZ make it difficult to determine the relationship between clinical characteristics and its concentration. We intended to present a machine learning (ML)-based method to predict toxic plasma trough concentration of VCZ (>5 μg/mL).

METHODS

A single center retrospective study was conducted. Three ML algorithms were used to estimate the concentration in adult patients, including random forest (RF), gradient boosting (GB), and extreme gradient boosting (XGBoost). The importance of variables was recognized by the SHapley Additive exPlanations (SHAP) method. In addition, an external validation set was used to validate the robustness of models.

RESULTS

A total of 1318 VCZ plasma concentration were included, with 33 variables enrolled in the model. Nine classification models were developed using the RF, GB, and XGBoost algorithms. Most models performed well for both the training set and test set, with an average balanced accuracy (BA) of 0.704 and an average accuracy (ACC) of 0.788. In addition, the average Matthews correlation coefficient value reached 0.484, which indicated the predicted values are meaningful. Based on the average BA and ACC values, the predictive ability of the models can be ranked from best to worst as follows: younger adult models > mixed models > elderly models, and XGBoost models > GBT models > RF models. The SHAP results showed that the top five influencing factors in younger adult patients (<60 years) were albumin, total bile acid (TBA), platelets count, age, and inflammation, while the top five influencing factors in elderly patients were albumin, TBA, aspartate aminotransferase, creatinine, and alanine aminotransferase. Furthermore, the prediction of external validation set for VCZ concentrations verified the high reliability of the models, for the ACC value of 0.822 by the best model.

CONCLUSIONS

The ML models can be reliable tools for predicting toxic concentration exposure of VCZ. The SHAP results may provide useful guidelines for dosage adjustment of VCZ.

Voriconazole Pharmacokinetics in Critically Ill Patients and Extracorporeal Membrane Oxygenation Support: A Retrospective Comparative Case-Control Study

Voriconazole, an antifungal agent, displays high intra- and inter-individual variability. The predictive pharmacokinetic (PK) index requires a minimum plasma concentration (C_min) in patient serum of between 1-5.5 mg/L. It is common to encounter fungal infections in patients undergoing extracorporeal membrane oxygenation (ECMO) support, and data regarding voriconazole PK changes during ECMO are scarce. Our study compared voriconazole PKs in patients with and without ECMO support in a retrospective cohort of critically-ill patients. Fifteen patients with 26 voriconazole C_min determinations in the non-ECMO group and nine patients with 27 voriconazole C_min determinations in the ECMO group were recruited. The ECMO group had lower C_min (0.38 ± 2.98 vs. 3.62 ± 3.88, p < 0.001) and higher infratherapeutic C_min values (16 vs. 1, p < 0.001) than the non-ECMO group. Multivariate analysis identified ECMO support (-0.668, CI₉₅ -0.978--0.358) and plasma albumin levels (-0.023, CI₉₅ -0.046--0.001) as risk factors for low C_min values. When comparing pre- and post-therapeutic drug optimisation samples from the ECMO group, the dose required to achieve therapeutic C_min was 6.44 mg/kg twice a day. Therapeutic drug optimisation is essential to improve target attainment.

Pharmacokinetics of Voriconazole in Peritoneal Fluid of Critically Ill Patients

Data on the distribution of voriconazole (VRC) in the human peritoneal cavity are sparse. This prospective study aimed to describe the pharmacokinetics of intravenous VRC in the peritoneal fluid of critically ill patients. A total of 19 patients were included. Individual pharmacokinetic curves, drawn after single (first dose on day 1) and multiple (steady-state) doses, displayed a slower rise and lower fluctuation of VRC concentrations in peritoneal fluid than in plasma. Good but variable penetration of VRC into the peritoneal cavity was observed, and the median (range) peritoneal fluid/plasma ratios of the area under the concentration-time curve (AUC) were 0.54 (0.34 to 0.73) and 0.67 (0.63 to 0.94) for single and multiple doses, respectively. Approximately 81% (13/16) of the VRC steady-state trough concentrations (Cmin,ss) in plasma were within the therapeutic range (1 to 5.5 μg/mL), and the corresponding Cmin,ss (median [range]) in peritoneal fluid was 2.12 (1.39 to 3.72) μg/mL. Based on the recent 3-year (2019 to 2021) surveillance of the antifungal susceptibilities for Candida species isolated from peritoneal fluid in our center, the aforementioned 13 Cmin,ss in peritoneal fluid exceeded the MIC90 of C. albicans, C. glabrata, and C. parapsilosis (0.06, 1.00, and 0.25 μg/mL, respectively), which supported VRC as a reasonable choice for initial empirical therapies against intraabdominal candidiasis caused by these three Candida species, prior to the receipt of susceptibility testing results.

Hypoalbuminemia and Pharmacokinetics: When the Misunderstanding of a Fundamental Concept Leads to Repeated Errors over Decades

Surprisingly, misinterpretation of the influence of hypoalbuminemia on pharmacokinetics and the clinical effects of drugs seems to be a current problem, even though hypoalbuminemia has no impact on the pharmacologically active exposure. Exceptions to this fact are highly protein-bound anaesthetics with high elimination capacity (i.e., <5 drugs on the market). To assess the frequency of misinterpretation of the influence of hypoalbuminemia on pharmacokinetics and the clinical effects of drugs between 1975 and 2021, a PubMed literature review was conducted. Each paragraph on albumin binding was classified as correct, ambiguous or incorrect, creating two acceptable categories: (1) content without any errors, and (2) content containing some incorrect and/or ambiguous statements. The analyses of these articles showed that fewer than 11% of articles contained no interpretation errors. In order to contain this misinterpretation, several measures are proposed: (1) Make the message accessible to a wide audience by offering a simplified and didactic video representation of the lack of impact of albumin binding to drugs. (2) Precise terminology (unbound/free form/concentration) should be used for highly bound drugs. (3) Unbound/free forms should be systematically quantified for highly plasma protein bound drugs for clinical trials as well as for therapeutic drug monitoring.

Factors influencing plasma concentration of voriconazole and voriconazole- N-oxide in younger adult and elderly patients

Background: Voriconazole (VCZ) metabolism is influenced by many factors. Identifying independent influencing factors helps optimize VCZ dosing regimens and maintain its trough concentration (C₀) in the therapeutic window. Methods: We conducted a prospective study investigating independent factors influencing VCZ C₀ and the VCZ C₀ to VCZ N-oxide concentration ratio (C₀/C_N) in younger adults and elderly patients. A stepwise multivariate linear regression model, including the IL-6 inflammatory marker, was used. The receiver operating characteristic (ROC) curve analysis was used to evaluate the predictive effect of the indicator. Results: A total of 463 VCZ C₀ were analyzed from 304 patients. In younger adult patients, the independent factors that influenced VCZ C₀ were the levels of total bile acid (TBA) and glutamic-pyruvic transaminase (ALT) and the use of proton-pump inhibitors. The independent factors influencing VCZ C₀/C_N were IL-6, age, direct bilirubin, and TBA. The TBA level was positively associated with VCZ C₀ (ρ = 0.176, p = 0.019). VCZ C₀ increased significantly when the TBA levels were higher than 10 μmol/L (p = 0.027). ROC curve analysis indicated that when the TBA level ≥4.05 μmol/L, the incidence of a VCZ C₀ greater than 5 μg/ml (95% CI = 0.54-0.74) (p = 0.007) increased. In elderly patients, the influencing factors of VCZ C₀ were DBIL, albumin, and estimated glomerular filtration rate (eGFR). The independent factors that affected VCZ C₀/C_N were eGFR, ALT, γ-glutamyl transferase, TBA, and platelet count. TBA levels showed a positive association with VCZ C₀ (ρ = 0.204, p = 0.006) and C₀/C_N (ρ = 0.342, p < 0.001). VCZ C₀/C_N increased significantly when TBA levels were greater than 10 μmol/L (p = 0.025). ROC curve analysis indicated that when the TBA level ≥14.55 μmol/L, the incidence of a VCZ C₀ greater than 5 μg/ml (95% CI = 0.52-0.71) (p = 0.048) increased. Conclusion: TBA level may serve as a novel marker for VCZ metabolism. eGFR and platelet count should also be considered when using VCZ, especially in elderly patients.

Linezolid pharmacokinetics: a systematic review for the best clinical practice

OBJECTIVES

To summarize the pharmacokinetics of linezolid to optimize the dosing regimen in special populations.

METHODS

A literature search was performed in three largest medical databases, including Embase, Scopus, and PubMed. The main applied keywords were linezolid and pharmacokinetics. Of 3663 retrieved publications in the English language, 35 original research articles, clinical studies, and case reports about linezolid pharmacokinetics in different populations such as pregnant women, pediatrics, elderly subjects, obese people, individuals with organ dysfunction, and critically ill patients were included. RESULTS AND CONCLUSION: Dose adjustment is not currently recommended for linezolid in patients with mild to moderate renal or hepatic impairment, older adults, and pregnant women. Although dose adjustment is not recommended in patients with severe renal or hepatic impairment, it should be considered that these patients are more vulnerable to linezolid adverse effects and drug interactions. In pediatrics, reducing the linezolid dosing interval to 8 h is suggested. Despite the lack of sufficient information in obese individuals, dosing based on body weight or use of higher dose seems to be justifiable to prevent sub-therapeutic concentrations. Although dose adjustment of linezolid is not recommended in critically ill patients, administration of linezolid as continuous intravenous infusion is suggested in this population. Blood level monitoring should be considered in populations that are vulnerable to linezolid underexposure (such as critically ill patients with augmented renal clearance, pediatrics, overweight, and obese patients) or overexposure (such as elderly, patients with hepatic and renal impairment). To assess the efficacy and safety of linezolid, the area under the concentration-time curve over 24 h to minimum inhibitory concentration (AUC0-24 h/MIC) equal to 80-120, percentage of time above the MIC ≥ 85%, and serum trough concentration between 2 and 7 mg/L are suggested.

Site-Directed Spin Labeling EPR Spectroscopy for Determination of Albumin Structural Damage and Hypoalbuminemia in Critical COVID-19

The main factors in the COVID-19 pathology, which can initiate extensive structural changes at the cellular and molecular levels, are the generation of free radicals in abnormal amounts, and oxidative stress. Under "oxidative shock" conditions, the proteins undergo various modifications that affect their function and activity, and as a result distribute malfunctioning protein derivatives in the body. Human serum albumin is a small globular protein characterized by a high overall binding capacity for neutral lipophilic and acidic dosage forms. The albumin concentration is crucial for the maintenance of plasma oncotic pressure, the transport of nutrients, amino acids, and drugs, the effectiveness of drug therapy, and the prevention of drug toxicity. Hypoalbuminemia and structural defects molecule in the protein suggest a risk of changed metabolism and increased plasma concentration of unbound drugs. Therefore, the albumin structural and functional changes accompanied by low protein levels can be a serious prerequisite for ineffective therapy, frequent complications, and high mortality in patients with SARS-CoV-2 infection. The current opinion aims the research community the application of Site-Directed Spin Labeling Electron Paramagnetic Resonance spectroscopy (SDSL-EPR) and 3-Maleimido-PROXYL radical in determining abnormalities of the albumin dynamics and protein concentrations in COVID-19 critical patients.

Voriconazole therapeutic drug monitoring and hepatotoxicity in critically ill patients: A nationwide multi-centre retrospective study

OBJECTIVES

To characterize trough concentrations (C_min) of voriconazole and associated hepatotoxicity, and to determine predictors of hepatotoxicity and identify high-risk groups in critically ill patients.

METHODS

This was a nationwide, multi-centre, retrospective study. C_min and hepatotoxicity were studied from 2015 to 2020 in 363 critically ill patients who received voriconazole treatment. Logistic regression and classification and regression tree (CART) models were used to identify high-risk patients.

RESULTS

Large interindividual variability was observed in initial voriconazole C_min and concentrations ranged from 0.1 mg/L to 18.72 mg/L. Voriconazole-related grade ≥2 hepatotoxicity developed in 101 patients, including 48 patients with grade ≥3 hepatotoxicity. The median time to hepatotoxicity was 3 days (range 1-24 days), and 83.2% of cases of hepatotoxicity occurred within 7 days of voriconazole initiation. Voriconazole C_min was significantly associated with hepatotoxicity. The CART model showed that significant predictors of grade ≥2 hepatotoxicity were C_min >3.42 mg/L, concomitant use of trimethoprim-sulfamethoxazole or tigecycline, and septic shock. The model predicted that the incidence of grade ≥2 hepatotoxicity among these high-risk patients was 48.3-63.4%. Significant predictors of grade ≥3 hepatotoxicity were C_min >6.87 mg/L, concomitant use of at least three hepatotoxic drugs, and septic shock; the predictive incidence among these high-risk patients was 22.7-36.8%.

CONCLUSION

Higher voriconazole C_min, septic shock and concomitant use of hepatotoxic drugs were the strongest predictors of hepatotoxicity. Plasma concentrations of voriconazole should be monitored early (as soon as steady state is achieved) to avoid hepatotoxicity.

Inflammation Affects Liver Function and the Metabolism of Voriconazole to Voriconazole-N-Oxide in Adult and Elderly Patients

Background: The inner association of inflammation with voriconazole (VCZ) metabolism has not been fully investigated. We intend to investigate the effects of inflammation on liver function, VCZ trough concentration (C₀), C₀/dose ratio and the ratio of VCZ to VCZ-N-oxide concentration (C₀/C_N) in adult and elderly patients.

Methods: A single-center retrospective study was conducted among patients who were treated in our hospital between January 2018 and December 2021. For each eligible patient, demographic details, medical history, laboratory parameters, procalcitonin (PCT), C reactive protein (CRP), and interleukin-6 (IL-6) were collected from the medical chart. VCZ C_N, TNF-α, IL-1β, IL-8, and IL-10 concentrations were detected in blood samples.

Results: A total of 356 patients were included in our study, with 195 patients in the adult cohort (<60 years) and 161 patients in the elderly cohort (≥60 years). In adult patients, CRP and IL-8 levels showed moderate association with VCZ C₀/C_N ratio (CRP: r = 0.512, p < 0.001; IL-8: r = 0.476, p = 0.002). IL-6 level shallowly associated with VCZ C₀/C_N ratio both in adult and elderly patients (r = 0.355, p = 0.003; r = 0.386, p = 0.001). A significantly higher VCZ C₀, C₀/dose ratio and C₀/C_N ratio was observed in adult patients with severe inflammation compared with patients with moderate inflammation and no to mild inflammation, as reflected by PCT levels (p < 0.05). However, there was no significant difference observed among different inflammation degrees in elderly patients. Lower albumin (AL) and higher total bilirubin (TBIL) were observed along with the degree of inflammation in both adult and elderly patients, as reflected by CRP and PCT levels (p < 0.05).

Conclusion: Inflammation may affect the metabolism of VCZ to VCZ-N-oxide both in adult and elderly patients, and decreased plasma AL levels and increased TBIL levels under inflammatory conditions may also alter VCZ metabolism.

Clinical Features, Diagnostic Test Performance, and Prognosis in Different Subtypes of Chronic Pulmonary Aspergillosis

Objective

The aim of this study was to describe clinical features in different subtypes of chronic pulmonary aspergillosis (CPA)-simple aspergilloma (SA), chronic cavitary pulmonary aspergillosis (CCPA), chronic fibrosing pulmonary aspergillosis (CFPA), aspergillus nodule (AN), and subacute invasive aspergillosis (SAIA), respectively, and identify long-term prognosis of CPA.

Methods

We reviewed patients diagnosed with different subtypes of CPA from 2002 to 2020 at Nanjing Jinling Hospital, China. We analyzed the clinical and survival information of five different subgroups. A Cox regression model was used to explore proper antifungal duration and long-term survival factors of CCPA and SAIA.

Results

A total of 147 patients with CPA were included, consisting of 11 SA, 48 CCPA, 5 CFPA, 12 AN, and 71 SAIA. The most common underlying pulmonary disease was pulmonary tuberculosis (n = 49, 33%), followed by bronchiectasis (n = 46, 31.3%) and chronic obstructive pulmonary disease (COPD) or emphysema (n = 45, 30.6%), while in SAIA and CFPA groups, the most common was COPD or emphysema (45.1 and 100%). Cough (85%), expectoration (70.7%), hemoptysis (54.4%), and fever (29.9%) were common symptoms, especially in CCPA, CFPA, and SAIA groups. The common imaging manifestations included cavitation (n = 94, 63.9%), fungal ball (n = 54, 36.7%), pleural thickening (n = 47, 32.0%), and bronchiectasis (n = 46, 31.3%). SAIA and CFPA groups had a lower value of hemoglobin (HB) and serum albumin (ALB) with higher C-reactive protein and erythrocyte sedimentation rate. The positive rate of sputum culture, serum galactomannan (GM), and bronchoalveolar lavage fluid GM was 32.7% (36/110), 18.4% (18/98), and 48.7% (19/39), respectively. There were 64.6% (31/48) patients with CCPA and 25.4% (18/71) patients with SAIA who received surgery and the 5-year cumulative survival rate was 92.1 and 66.6%, respectively. SAIA, old age, male, low body mass index (BMI), COPD or emphysema, multiple distribution, low serum ALB, and positive sputum culture were adverse prognosis factors for SAIA and CCPA group, and BMI ≤ 20.0 kg/m² was independently associated with increased mortality (hazard ratio (HR) 5.311, 95% CI 1.405–20.068, p = 0.014). Multivariable Cox regression indicated that surgery (HR 0.093, 95% CI 0.011–0.814, p = 0.032) and antifungal duration >6 months (HR 0.204, 95% CI 0.060–0.696 p = 0.011) were related to improved survival.

Conclusion

The clinical features and laboratory test performance are different among SA, CCPA, CFPA, AN, and SAIA. Low BMI was an independent risk factor for survival. Selective surgery and antifungal duration over 6 months were associated with improved survival.

Predictive Value of C-Reactive Protein and Albumin for Temporal Within-Individual Pharmacokinetic Variability of Voriconazole in Pediatric Hematopoietic Cell Transplant Patients

Voriconazole is a widely used antifungal agent in immunocompromised patients, but its utility is limited by its variable exposure and narrow therapeutic index. Population pharmacokinetic (PK) models have been used to characterize voriconazole PK and derive individualized dosing regimens. However, determinants of temporal within-patient variability of voriconazole PK were not well-established. We aimed to characterize temporal variability of voriconazole PK within individuals and identify predictive clinical factors. This study was conducted as a part of a single-institution, phase I study of intravenous voriconazole in children undergoing HCT (NCT02227797). We analyzed voriconazole PK study data collected at week 1 and again at week 2 after the start of voriconazole therapy in 59 pediatric HCT patients (age <21 years). Population PK analysis using nonlinear mixed effect modeling was performed to analyze temporal within-individual variability of voriconazole PK by incorporating a between-occasion variability term in the model. A two-compartment linear elimination model incorporating body weight and CYP2C19 phenotype described the data. Ratio of individual voriconazole clearance between weeks 1 to 2 ranged from 0.11 to 3.3 (-9.1 to +3.3-fold change). Incorporation of covariate effects by serum C-reactive protein (CRP) and albumin levels decreased between-occasion variability of clearance (coefficient of variation: from 59.5% to 41.2%) and improved the model fit (p<0.05). As significant covariates on voriconazole PK, CRP and albumin concentrations may potentially serve as useful biomarkers as part of therapeutic drug monitoring. This article is protected by copyright. All rights reserved.

Recent Advances in Therapeutic Drug Monitoring of Voriconazole, Mycophenolic Acid, and Vancomycin: A Literature Review of Pediatric Studies

The review includes studies dated 2011-2021 presenting the newest information on voriconazole (VCZ), mycophenolic acid (MPA), and vancomycin (VAN) therapeutic drug monitoring (TDM) in children. The need of TDM in pediatric patients has been emphasized by providing the information on the differences in the drugs pharmacokinetics. TDM of VCZ should be mandatory for all pediatric patients with invasive fungal infections (IFIs). Wide inter- and intrapatient variability in VCZ pharmacokinetics cause achieving and maintaining therapeutic concentration during therapy challenging in this population. Demonstrated studies showed, in most cases, VCZ plasma concentrations to be subtherapeutic, despite the updated dosages recommendations. Only repeated TDM can predict drug exposure and individualizing dosing in antifungal therapy in children. In children treated with mycophenolate mofetil (MMF), similarly as in adult patients, the role of TDM for MMF active form, MPA, has not been well established and is undergoing continued debate. Studies on the MPA TDM have been carried out in children after renal transplantation, other organ transplantation such as heart, liver, or intestine, in children after hematopoietic stem cell transplantation or cord blood transplantation, and in children with lupus, nephrotic syndrome, Henoch-Schönlein purpura, and other autoimmune diseases. MPA TDM is based on the area under the concentration-time curve; however, the proposed values differ according to the treatment indication, and other approaches such as pharmacodynamic and pharmacogenetic biomarkers have been proposed. VAN is a bactericidal agent that requires TDM to prevent an acute kidney disease. The particular group of patients is the pediatric one. For this group, the general recommendations of the dosing may not be valid due to the change of the elimination rate and volume of distribution between the subjects. The other factor is the variability among patients that concerns the free fraction of the drug. It may be caused by both the patients' population and sample preconditioning. Although VCZ, MMF, and VAN have been applied in pediatric patients for many years, there are still few issues to be solve regarding TDM of these drugs to ensure safe and effective treatment. Except for pharmacokinetic approach, pharmacodynamics and pharmacogenetics have been more often proposed for TDM.

Population pharmacokinetic model-guided optimization of intravenous voriconazole dosing regimens in critically ill patients with liver dysfunction

STUDY OBJECTIVES

This study aimed to establish a population pharmacokinetic (PPK) model of intravenous voriconazole (VRC) in critically ill patients with liver dysfunction and to explore the optimal dosing strategies in specific clinical scenarios for invasive fungal infections (IFIs) caused by common Aspergillus and Candida species.

DESIGN

Prospective pharmacokinetics study.

SETTING

The intensive care unit in a tertiary-care medical center.

PATIENTS

A total of 297 plasma VRC concentrations from 26 critically ill patients with liver dysfunction were included in the PPK analysis.

METHODS

Model-based simulations with therapeutic range of 2-6 mg/L as the plasma trough concentration (C_min ) target and the free area under the concentration-time curve from 0 to 24 h (ƒAUC₂₄ ) divided by the minimum inhibitory concentration (MIC) (ie, ƒAUC₂₄ /MIC) ≥25 as the effective target were performed to optimize VRC dosing regimens for Child-Pugh class A and B (CP-A/B) and Child-Pugh class C (CP-C) patients.

RESULTS

A two-compartment model with first-order elimination adequately described the data. Significant covariates in the final model were body weight on both central and peripheral distribution volume and Child-Pugh class on clearance. Intravenous VRC loading dose of 5 mg/kg every 12 h (q12h) for the first day was adequate for CP-A/B and CP-C patients to attain the C_min target at 24 h. The maintenance dose regimens of 100 mg q12h or 200 mg q24h for CP-A/B patients and 50 mg q12h or 100 mg q24h for CP-C patients could obtain the probability of effective target attainment of >90% at an MIC ≤0.5 mg/L and achieve the cumulative fraction of response of >90% against C. albicans, C. parapsilosis, C. glabrata, C. krusei, A. fumigatus, and A. flavus. Additionally, the daily VRC doses could be increased by 50 mg for CP-A/B and CP-C patients at an MIC of 1 mg/L, with plasma C_min monitored closely to avoid serious adverse events. It is recommended that an appropriate alternative antifungal agent or a combination therapy could be adopted when an MIC ≥2 mg/L is reported, or when the infection is caused by C. tropicalis but the MIC value is not available.

CONCLUSIONS

For critically ill patients with liver dysfunction, the loading dose of intravenous VRC should be reduced to 5 mg/kg q12h. Additionally, based on the types of fungal pathogens and their susceptibility to VRC, the adjusted maintenance dose regimens with lower doses or longer dosing intervals should be considered for CP-A/B and CP-C patients.

Voriconazole Pharmacokinetics Are Not Altered in Critically Ill Patients with Acute-on-Chronic Liver Failure and Continuous Renal Replacement Therapy: An Observational Study

Infection and sepsis are a main cause of acute-on-chronic liver failure (ACLF). Besides bacteria, molds play a role. Voriconazole (VRC) is recommended but its pharmacokinetics (PK) may be altered by ACLF. Because ACLF patients often suffer from concomitant acute renal failure, we studied the PK of VRC in patients receiving continuous renal replacement therapy (RRT) with ACLF and compared it to PK of VRC in critically ill patients with RRT without concomitant liver failure (NLF). In this prospective cohort study, patients received weight-based VRC. Pre- and post-dialysis membrane, and dialysate samples obtained at different time points were analyzed by high-performance liquid chromatography. An integrated dialysis pharmacometric model was used to model the available PK data. The recommended, 50% lower, and 50% higher doses were analyzed by Monte-Carlo simulation (MCS) for day 1 and at steady-state with a target trough concentration (TC) of 0.5–3mg/L. Fifteen patients were included in this study. Of these, 6 patients suffered from ACLF. A two-compartment model with linear clearance described VRC PK. No difference for central (V1) or peripheral (V2) volumes of distribution or clearance could be demonstrated between the groups. V1 was 80.6L (95% confidence interval: 62.6–104) and V2 106L (65–166) with a body clearance of 4.7L/h (2.87–7.81) and RRT clearance of 1.46L/h (1.29–1.64). MCS showed TC below/within/above target of 10/74/16% on day 1 and 9/39/52% at steady-state for the recommended dose. A 50% lower dose resulted in 26/72/1% (day 1) and 17/64/19% at steady-state and 7/57/37% and 7/27/67% for a 50% higher dose. VRC pharmacokinetics are not significantly influenced by ACLF in critically ill patients who receive RRT. Maintenance dose should be adjusted in both groups. Due to the high interindividual variability, therapeutic drug monitoring seems inevitable.

Pharmacological management of antifungal agents in pulmonary aspergillosis: an updated review

INTRODUCTION

Aspergillus may cause different types of lung infections: invasive, chronic pulmonary or allergic bronchopulmonary aspergillosis. Pharmacological management with antifungals poses as a challenge. Patients diagnosed with pulmonary aspergillosis are complex, as well as the problems associated with antifungal agents.

AREAS COVERED

This article reviews the pharmacology of antifungal agents in development and currently used to treat pulmonary aspergillosis, including the mechanisms of action, pharmacokinetics, pharmacodynamics, dosing, therapeutic drug monitoring and safety. Recommendations to manage situations that arise in daily clinical practice are provided. A literature search of PubMed was conducted on November 15^th, 2020 and updated on March 30^th, 2021.

EXPERT OPINION

Recent and relevant developments in the treatment of pulmonary aspergillosis have taken place. Novel antifungals with new mechanisms of action that extend antifungal spectrum and improve pharmacokinetic-related aspects, drug-drug interactions and safety are under current study. For those antifungals already marketed, new data related to pharmacokinetics, pharmacodynamics, dose adjustments in special situations, therapeutic drug monitoring and safety are available. To maximize efficacy and reduce the risk of associated toxicities, it is essential to choose the most appropriate antifungal; optimize its dose, interval, route of administration and length of treatment; and prevent side effects.

Prediction of Unbound Vancomycin Levels in Intensive Care Unit and Nonintensive Care Unit Patients: Total Bilirubin May Play an Important Role

Background

The mean unbound vancomycin fraction and whether the unbound vancomycin level could be predicted from the total vancomycin level are still controversial, especially for patients in different groups, such as intensive care unit (ICU) versus non-ICU patients. Other relevant potential patient characteristics that may predict unbound vancomycin levels have yet to be clearly determined.

Methods

We enrolled a relatively large study population and included widely comprehensive potential covariates to evaluate the unbound vancomycin fractions in a cohort of ICU (n=117 samples) and non-ICU patients (n=73 samples) by using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method.

Results

The mean unbound vancomycin fraction was 45.80% ± 18.69% (median, 46.01%; range: 2.13–99.45%) in the samples from the total population. No significant differences in the unbound vancomycin fraction were found between the ICU patients and the non-ICU patients (P=0.359). A significant correlation was established between the unbound and total vancomycin levels. The unbound vancomycin level can be predicted with the following equations: unbound vancomycin level=0.395×total vancomycin level+0.019×total bilirubin level+0.468 (R²=0.771) for the ICU patients and unbound vancomycin level=0.526×total vancomycin level-0.527 (R²=0.749) for the non-ICU patients. Overall, the observed-versus-predicted plots were acceptable.

Conclusion

A significant correlation between the total and unbound vancomycin levels was found, and measurement of the unbound vancomycin level seems to have no added value over measurement of the total vancomycin level. The study developed parsimonious equations for predicting the unbound vancomycin level and provides a reference for clinicians to predict the unbound vancomycin level in adult populations.

Determination of Voriconazole Plasma Concentration by HPLC Technique and Evaluating Its Association with Clinical Outcome and Adverse Effects in Patients with Invasive Aspergillosis

Purpose

Invasive aspergillosis is a prevalent fungal disease, especially in Asian countries with a high mortality rate. Voriconazole (VRZ) is the first choice for invasive aspergillosis treatment. Plasma concentration of this drug is unpredictable and varies among individuals. This variability is influenced by many factors leading to clinical implication. Therapeutic drug monitoring (TDM) may have a crucial role in the patients' treatment process. The HPLC method provides sufficient specificity and sensitivity for plasma VRZ concentration determination for TDM purposes of this drug.

Methods

Patients who initiated oral or intravenous VRZ for invasive aspergillosis were enrolled in this study. Demographic characteristics and clinical data, outcome, and adverse effects were documented. For each patient, the plasma sample was collected under steady-state condition and analyzed using a validated HPLC method.

Results

A total of 22 measurements were performed. Fifty percent of patients were out of the therapeutic range. From them, 27.27% and 22.73% were in subtherapeutic and supratherapeutic ranges (<1 μg/mL and >5.5 μg/mL), respectively. There was a significant correlation between VRZ plasma concentration and treatment outcomes (P=0.022). Treatment failure was five times higher than treatment success in those in the subtherapeutic range. Adverse effects were observed more frequently in patients with supratherapeutic concentrations compared to those with non-supratherapeutic levels. Furthermore, the mortality rate in patients experiencing treatment failure was 2.17 times higher than those with treatment success.

Conclusions

TDM of VRZ plays an important role in better evaluation of efficacy and toxicity during treatment. Therefore, determination of the drug level may be of clinical significance.

Clinical features and Outcomes of Cryptococcemia patients with and without HIV infection

BACKGROUND

The effects of cryptococcemia on patient outcomes in those with or without HIV remain unclear.

METHODS

One hundred and seventy-nine cryptococcemia patients were enrolled in this retrospective study. Demographic characteristics, blood test results and outcome were compared between the two groups.

RESULTS

The diagnosis time of Cryptococcus infection was 2.0(0-6.0) days for HIV-infected patients, 5.0 (1.5-8.0) days for HIV-uninfected patients (p = .008), 2.0 (1.0-6.0) days for cryptococcal meningitis (CM) patients and 6.0 (5.0-8.0) days for non-CM patients (p < .001). HIV infection [adjusted odds ratio (AOR) (95% confidence interval): 6.0(2.3-15.9)], CRP < 15 mg/L [AOR:3.7(1.7-8.1)) and haemoglobin > 110 g/L [AOR:2.5(1.2-5.4)] were risk factors for CM development. Forty-six (25.7%) patients died within 90 days. ICU stay [AOR:2.8(1.1-7.1)], hypoalbuminemia [AOR:2.7(1.4-5.3)], no anti-cryptococcal treatment [AOR:4.7(1.9-11.7)] and altered consciousness [AOR:2.4(1.0-5.5)] were independent risk factors for 90-day mortality in all patients. HIV infection did not increase the 90-day mortality of cryptococcemia patients when anti-Cryptococcus treatment was available. Non-Amphotericin B treatment [AOR:3.4(1.0-11.2)] was associated with 90-day mortality in HIV-infected patients, but age ≥ 50.0 years old [AOR:2.7(1.0-2.9)], predisposing disease [AOR:4.1(1.2-14.2)] and altered consciousness [AOR:3.7(1.1-12.9)] were associated with 90-day mortality in HIV-uninfected patients who accepted anti-Cryptococcus treatment.

CONCLUSION

HIV infection increased the incidence of CM rather than mortality in cryptococcemia patients. The predictive model was completely divergent in HIV-infected and HIV-uninfected patients, suggesting that novel strategies for diagnosis and treatment algorithms are urgently needed.

Optimization of voriconazole therapy for treatment of invasive aspergillosis: Pharmacogenomics and inflammatory status need to be evaluated

AIMS

Cytochrome 2C19 genotype-directed dosing of voriconazole (VRC) reduces the incidence of insufficient VRC trough concentrations (C_min ) but does not account for CYP3A polymorphisms, also involved in VRC metabolism. This prospective observational study aimed to evaluate the utility of a genetic score combining CYP2C19 and CYP3A genotypes to predict insufficient initial VRC C_min (<1 mg/L).

METHODS

The genetic score was determined in hematological patients treated with VRC. The higher the genetic score, the faster the metabolism of the patient. The impact of the genetic score was evaluated considering initial VRC C_min and all VRC C_min (n = 159) determined during longitudinal therapeutic drug monitoring.

RESULTS

Forty-three patients were included, of whom 41 received VRC for curative indication. Thirty-six patients had a genetic score ≥2, of whom 11 had an initial insufficient VRC C_min . A genetic score ≥2 had a positive predictive value of 0.31 for having an initial insufficient VRC C_min and initial VRC C_min was not associated with the genetic score. The lack of association between the genetic score and VRC C_min may be related to the inflammatory status of the patients (C-reactive protein [CRP] levels: median [Q1-Q3]: 43.0 [11.0-110.0] mg/L), as multivariate analysis performed on all VRC C_min identified CRP as an independent determinant of the VRC C_min adjusted for dose (P < .0001).

CONCLUSION

The combined genetic score did not predict low VRC exposure in patients with inflammation, which is frequent in patients with invasive fungal infections. Strategies for the individualization of VRC dose should integrate the inflammatory status of patients in addition to pharmacogenetic variants.

Predictors of Adverse Events and Determinants of the Voriconazole Trough Concentration in Kidney Transplantation Recipients

Voriconazole is the mainstay for the treatment of invasive fungal infections in patients who underwent a kidney transplant. Variant CYP2C19 alleles, hepatic function, and concomitant medications are directly involved in the metabolism of voriconazole. However, the drug is also associated with numerous adverse events. The purpose of this study was to identify predictors of adverse events using binary logistic regression and to measure its trough concentration using multiple linear modeling. We conducted a prospective analysis of 93 kidney recipients cotreated with voriconazole and recorded 213 trough concentrations of it. Predictors of the adverse events were voriconazole trough concentration with the odds ratios (OR) of 2.614 (P = 0.016), cytochrome P450 2C19 (CYP2C19), and hemoglobin (OR 0.181, P = 0.005). The predictive power of these three factors was 91.30%. We also found that CYP2C19 phenotypes, hemoglobin, platelet count, and concomitant use of ilaprazole had quantitative relationships with voriconazole trough concentration. The fit coefficient of this regression equation was R²  = 0.336, demonstrating that the model explained 33.60% of interindividual variability in the disposition of voriconazole. In conclusion, predictors of adverse events are CYP2C19 phenotypes, hemoglobin, and voriconazole trough concentration. Determinants of the voriconazole trough concentration were CYP2C19 phenotypes, platelet count, hemoglobin, concomitant use of ilaprazole. If we consider these factors during voriconazole use, we are likely to maximize the treatment effect and minimize adverse events.

Challenges in Antifungal Therapy in Diabetes Mellitus

Diabetic patients have an increased propensity to Candida sp. infections due to disease-related immunosuppression and various other physiological alterations. The incidence of candidiasis has increased in number over the years and is linked to significant morbidity and mortality in critically ill and immunosuppressed patients. Treatment of infection in diabetic patients may be complicated due to the various disease-related changes to the pharmacokinetics and pharmacodynamics (PK/PD) of a drug, including antifungal agents. Application of PK/PD principles may be a sensible option to optimise antifungal dosing regimens in this group of patients. Further studies on PK/PD of antifungals in patients with diabetes mellitus are needed as current data is limited or unavailable.

Impact of Albumin and Omeprazole on Steady-State Population Pharmacokinetics of Voriconazole and Development of a Voriconazole Dosing Optimization Model in Thai Patients with Hematologic Diseases

This study aimed to identify factors that significantly influence the pharmacokinetics of voriconazole in Thai adults with hematologic diseases, and to determine optimal voriconazole dosing regimens. Blood samples were collected at steady state in 65 patients (237 concentrations) who were taking voriconazole to prevent or treat invasive aspergillosis. The data were analyzed using a nonlinear mixed-effects modeling approach. Monte Carlo simulation was applied to optimize dosage regimens. Data were fitted with the one-compartment model with first-order absorption and elimination. The apparent oral clearance (CL/F) was 3.43 L/h, the apparent volume of distribution (V/F) was 47.6 L, and the absorption rate constant (Ka) was fixed at 1.1 h⁻¹. Albumin and omeprazole ≥ 40 mg/day were found to significantly influence CL/F. The simulation produced the following recommended maintenance doses of voriconazole: 50, 100, and 200 mg every 12 h for albumin levels of 1.5–3, 3.01–4, and 4.01–4.5 g/dL, respectively, in patients who receive omeprazole ≤ 20 mg/day. Patients who receive omeprazole ≥ 40 mg/day and who have serum albumin level 1.5–3 and 3.01–4.5 g/dL should receive voriconazole 50 and 100 mg, every 12 h, respectively. Albumin level and omeprazole dosage should be carefully considered when determining the appropriate dosage of voriconazole in Thai patients.

Pharmacokinetic/Pharmacodynamic Analysis of Voriconazole Against Candida spp. and Aspergillus spp. in Allogeneic Stem Cell Transplant Recipients

BACKGROUND

To evaluate the adequacy of different dosing regimens of voriconazole for the prophylaxis of invasive candidiasis and aspergillosis in adult allogeneic stem cell transplant recipients by means of population pharmacokinetic (PK) modelling and simulation.

METHODS

Allogeneic stem cell transplant recipients receiving voriconazole were included in this observational study. A population PK model was developed. Three oral voriconazole-dosing regimens were simulated: 200, 300, and 400 mg twice daily. The pharmacodynamic target was defined as fAUC0-24/0.7. A probability of target attainment ≥90% was considered optimal. The cumulative fraction of response was defined as the fraction of patients achieving the pharmacodynamic target when a population of simulated patients is matched with a simulated population of different Candida spp. and Aspergillus spp. The percentage of patients with trough plasma concentrations at steady state (Ctrough) within the reference range (1-5.5 mg/L) was also calculated.

RESULTS

A 2-compartment PK model was developed using data from 40 patients, which contributed 237 voriconazole plasma samples, including trough and maximum concentrations. Voriconazole 200, 300, and 400 mg twice daily achieved probability of target attainment ≥90% for minimal inhibitory concentration values ≤0.25, ≤0.38, and ≤0.50 mg/L, respectively. The cumulative fraction of response for A. niger, A. versicolor, and A. flavus increased >10% when increasing voriconazole dose from 200 to 400 mg twice daily (from 72.5% to 89.5% for A. niger; from 77.7% to 88.7% for A. versicolor; and from 82.4% to 94.9% for A flavus). The percentage of patients with Ctrough within the reference range increased 15% when voriconazole dose was increased from 200 to 300 mg twice daily.

CONCLUSIONS

The PK simulations in this study suggest that transplant recipients on voriconazole prophylaxis against invasive candidiasis or aspergillosis are likely to achieve the target concentrations associated with the desired treatment outcomes if the maintenance dose is 200 mg twice daily. However, Aspergillus spp. with high minimal inhibitory concentrations could require higher maintenance doses.

Voriconazole therapeutic drug monitoring in critically ill patients improves efficacy and safety of antifungal therapy

Since voriconazole plasma trough concentration (VPC) is related to its efficacy and adverse events, therapeutic drug monitoring (TDM) is recommended to perform. However, there is no report about the data of voriconazole TDM in critically ill patients in China. This retrospective study was performed to determine whether voriconazole TDM was associated with treatment response and/or voriconazole adverse events in critically ill patients, and to identify the potential risk factors associated with VPC. A total of 216 critically ill patients were included. Patients were divided into two groups: those underwent voriconazole TDM (TDM group, n = 125) or did not undergo TDM (non-TDM group, n = 91). The clinical response and adverse events were recorded and compared. Furthermore, in TDM group, multivariate logistic regression analysis was performed to identify the possible risk factors resulting in the variability in initial VPC. The complete response in the TDM group was significantly higher than that in the non-TDM group (P = .012). The incidence of adverse events strongly associated with voriconazole in the non-TDM group was significantly higher than that in the TDM group (19.8% vs 9.6%; P = .033). The factors, including age (OR 0.934, 95% CI: 0.906-0.964), male (OR 5.929, 95% CI: 1.524-23.062), serum albumin level (OR 1.122, 95% CI: 1.020-1.234), diarrhoea (OR 4.953, 95% CI: 1.495-16.411) and non-intravenous administration (OR 4.763, 95% CI: 1.576-14.39), exerted the greatest effects on subtherapeutic VPC (VPC < 1.5 mg/L) in multivariate analysis. Intravenous administration (OR 7.657, 95% CI: 1.957-29.968) was a significant predictor of supratherapeutic VPC (VPC > 4.0 mg/L). TDM can result in a favourable clinical efficacy and a lower incidence of adverse events strongly associated with voriconazole in critically ill patients. Subtherapeutic VPC was closely related to younger age, male, hyperalbuminaemia, diarrhoea and non-intravenous administration, and intravenous administration was a significant predictor of supratherapeutic VPC.

Paclitaxel, Imatinib and 5-Fluorouracil Increase the Unbound Fraction of Flucloxacillin In Vitro

Flucloxacillin (FLU), an isoxazolyl penicillin, is widely used for the treatment of different bacterial infections in intensive care units (ICU). Being highly bound to plasma proteins, FLU is prone to drug-drug interactions (DDI) when administered concurrently with other drugs. As FLU is binding to both Sudlow’s site I and site II of human serum albumin (HSA), competitive and allosteric interactions with other drugs, highly bound to the same sites, seem conceivable. Knowledge about interaction(s) of FLU with the widely used anticancer agents paclitaxel (PAC), imatinib (IMA), and 5-fluorouracil (5-FU is scarce. The effects of the selected anticancer agents on the unbound fraction of FLU were evaluated in pooled plasma as well as in HSA and α-1-acid glycoprotein (AGP) samples, the second major drug carrier in plasma. FLU levels in spiked samples were analyzed by LC-MS/MS after ultrafiltration. Significant increase in FLU unbound fraction was observed when in combination with PAC and IMA and to a lesser extent with 5-FU. Furthermore, significant binding of FLU to AGP was observed. Collectively, this is the first study showing the binding of FLU to AGP as well as demonstrating a significant DDI between PAC/IMA/5-FU and FLU.

The Impact of Plasma Protein Binding Characteristics and Unbound Concentration of Voriconazole on Its Adverse Drug Reactions

This study investigated voriconazole (VRC) unbound plasma concentration and its relationship with adverse drug reactions (ADRs) in patients with malignant hematologic disease. Plasma samples were collected from patients or spiked in vitro. A time-saving rapid equilibrium dialysis assay was used for the separation of unbound and bound VRC, following a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis method for drug concentration detection. Liver function and treatment details were collected from the electronic medical records of patients. Protein concentration was determined according to instructions. VRC plasma protein binding rate (PPB) in patient is significantly higher [69.5 ± 6.2%] than that in in-vitro samples, influenced by total drug concentration (C_t), plasma protein concentration, and protein type. The α1-acid glycogen (AAG) has the highest affinity with VRC. Relationship between total PPB of VRC with PPB of individual protein is not a simple addition, but a compressive combination. Unbound drug concentration (C_u) of VRC shows significant relationships with C_t, protein concentration, AST level, metabolism type of CYP2C19 and co-administration of high PPB medicines. Unbound plasma concentration of VRC shows a more sensitive relationship with ADRs than C_t.

Risk factors associated with insufficient and potentially toxic voriconazole plasma concentrations: an observational study

The aim of this study was to identify potential factors associated with insufficient/toxic voriconazole trough concentrations (VTCs) in patients in order to screen the high-risk population. A total of 119 VTCs were obtained from 67 patients. Multivariate regression analysis suggested that insufficient VTCs (<1.0 mg/L) were significantly associated with younger age and underlying hematological malignancy, and toxic VTCs (>5.5 mg/L) were significantly associated with lower serum albumin (ALB) level. Receiver operating characteristic curve analysis indicated that patients whose age < 47 years were the high-risk population of insufficient VTCs, and patients whose ALB <27 g/L were the high-risk population of toxic VTCs. Younger age and underlying hematological malignancy were significant predictors of insufficient VTCs, and lower ALB level was found to be a significant predictor of toxic VTCs. Therefore, we recommend to increase the monitoring on these high-risk population to avoid treatment failure and to prevent toxic adverse events.

Impact of voriconazole plasma concentrations on treatment response in critically ill patients

WHAT IS KNOWN AND OBJECTIVE

Several authors have demonstrated the relationship between voriconazole concentrations and the risk of therapeutic failure and adverse events However, the information about voriconazole concentrations in the critically ill patient is scarce. The aim of this study was to analyse the plasma concentrations and pharmacokinetic behaviour of voriconazole in critically ill patients and their association with the treatment response and development of toxicity.

METHODS

A prospective, observational study was conducted. Patients admitted to an intensive care unit and on treatment with intravenous voriconazole were included. Plasma concentrations were measured between days 4 and 7 from the start of the treatment. The pharmacokinetic analysis was performed using the NONMEM^® software. A regression model was used to evaluate the variables associated with the values outside the therapeutic range, as well as the relationship between the plasma concentrations and the treatment response and the development of hepatotoxicity.

RESULTS AND DISCUSSION

A total of 33 patients were included. Plasma concentrations outside the therapeutic range (1-5.5 mg/L) were observed in 15 patients, being above the established range in 9 (27.3%) cases, and below it in 6 (18.2%) cases. The presence of a bilirubin value of >1.5 mg/dL and a C-reactive protein >100 mg/dL was associated with supra-therapeutic concentrations. Voriconazole concentrations greater than 5.5 mg/dL were associated with the development of hepatotoxicity.

WHAT IS NEW AND CONCLUSIONS

There is a wide variation in voriconazole concentrations in critically ill patients, being associated with a high frequency of adverse events. Close monitoring of these values is required in order to decrease the risk of therapeutic failure and toxicity.

Diagnosis and management of Aspergillus diseases: executive summary of the 2017 ESCMID-ECMM-ERS guideline

The European Society for Clinical Microbiology and Infectious Diseases, the European Confederation of Medical Mycology and the European Respiratory Society Joint Clinical Guidelines focus on diagnosis and management of aspergillosis. Of the numerous recommendations, a few are summarized here. Chest computed tomography as well as bronchoscopy with bronchoalveolar lavage (BAL) in patients with suspicion of pulmonary invasive aspergillosis (IA) are strongly recommended. For diagnosis, direct microscopy, preferably using optical brighteners, histopathology and culture are strongly recommended. Serum and BAL galactomannan measures are recommended as markers for the diagnosis of IA. PCR should be considered in conjunction with other diagnostic tests. Pathogen identification to species complex level is strongly recommended for all clinically relevant Aspergillus isolates; antifungal susceptibility testing should be performed in patients with invasive disease in regions with resistance found in contemporary surveillance programmes. Isavuconazole and voriconazole are the preferred agents for first-line treatment of pulmonary IA, whereas liposomal amphotericin B is moderately supported. Combinations of antifungals as primary treatment options are not recommended. Therapeutic drug monitoring is strongly recommended for patients receiving posaconazole suspension or any form of voriconazole for IA treatment, and in refractory disease, where a personalized approach considering reversal of predisposing factors, switching drug class and surgical intervention is also strongly recommended. Primary prophylaxis with posaconazole is strongly recommended in patients with acute myelogenous leukaemia or myelodysplastic syndrome receiving induction chemotherapy. Secondary prophylaxis is strongly recommended in high-risk patients. We strongly recommend treatment duration based on clinical improvement, degree of immunosuppression and response on imaging.

New insights into the clinical characteristics and prognostic factors of pulmonary fungal infections from a retrospective study in Southwestern China

Background

Despite increasing incidence of pulmonary fungal infections (PFIs) worldwide, the clinical characteristics and prognostic factors remain poorly understood. The goal of this study was to investigate the clinical features, laboratory findings, and outcomes of hospitalized patients diagnosed with PFIs.

Methods

We retrospectively enrolled 123 patients at a university hospital in Southwestern China between February 2014 and May 2016, who were diagnosed with PFIs based on clinical presentations and laboratory tests including fungal culture and pathological examination. Medical records were reviewed and analyzed. Prognostic factor associated with mortality was evaluated by multivariate regression analysis.

Results

Of the 123 PFI patients enrolled, the mean age was 67 years with 72% of them being males. In addition to common clinical features reported previously, these patients exhibited distinct characteristics, with the elderly accounting for 79% of all cases, and with prolonged hospitalization being the most prevalent risk factor (74%) and chronic obstructive pulmonary disease (COPD) being the most common underlying disease (45%). Invasive operation was significantly more frequently involved in patients with unfavorable treatment responses than in patients with favorable responses (45.6 vs 7.4%, P=0.000). By multivariate regression analysis, invasive operation (odds ratio [OR]: 5.736, 95% confidence interval [CI]: 2.008–16.389, P=0.001) and hypoalbuminemia (OR: 3.936, 95% CI: 1.325–11.696, P=0.014) were independent prognostic factors of mortality in PFIs.

Conclusion

This study provides new insights into the clinical characteristics and prognostic factors of PFIs and highlights the necessity to be aware of PFIs in patients with COPD and patients receiving invasive operation in order to improve clinical management of these patients.

Pharmacokinetic/pharmacodynamic considerations for the optimization of antimicrobial delivery in the critically ill

PURPOSE OF REVIEW

Antimicrobials are very commonly used drugs in the intensive care setting. Extensive research has been conducted in recent years to describe their pharmacokinetics/pharmacodynamics in order to maximize the pharmacological benefit and patient outcome. Translating these new findings into clinical practice is encouraged.

RECENT FINDINGS

This article will discuss mechanistic data on factors causing changes in antimicrobial pharmacokinetics in critically ill patients, such as the phenomena of augmented renal clearance as well as the effects of hypoalbuminemia, renal replacement therapy, and extracorporeal membrane oxygenation. Failure to achieve clinical cure has been correlated with pharmacokinetics/pharmacodynamics target nonattainment, and a recent meta-analysis suggests an association between dosing strategies aimed at optimizing antimicrobial pharmacokinetics/pharmacodynamics with improvement in clinical cure and survival. Novel dosing strategies including therapeutic drug monitoring are also now being tested to address challenges in the optimization of antimicrobial pharmacokinetics/pharmacodynamics.

SUMMARY

Optimization of antimicrobial dosing in accordance with pharmacokinetics/pharmacodynamics targets can improve survival and clinical cure. Dosing regimens for critically ill patients should aim for pharmacokinetics/pharmacodynamics target attainment by utilizing altered dosing strategies including adaptive feedback using therapeutic drug monitoring.

Investigation of Saliva as an Alternative to Plasma Monitoring of Voriconazole

BACKGROUND AND OBJECTIVES

Therapeutic drug monitoring (TDM) of voriconazole is increasingly being implemented in clinical practice. However, as blood sampling can be difficult in paediatric and ambulatory patients, a non-invasive technique for TDM is desirable. The aim of this study was to compare the pharmacokinetics of voriconazole in saliva with the pharmacokinetics of unbound and total voriconazole in plasma in order to clinically validate saliva as an alternative to plasma in voriconazole TDM.

METHODS

In this pharmacokinetic study, paired plasma and saliva samples were taken at steady state in adult haematology and pneumology patients treated with voriconazole. Unbound and bound plasma voriconazole concentrations were separated using high-throughput equilibrium dialysis. Voriconazole concentrations were determined with liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters were calculated using log-linear regression.

RESULTS

Sixty-three paired samples were obtained from ten patients (seven haematology and three pneumology patients). Pearson's correlation coefficients (R values) for saliva versus unbound and total plasma voriconazole concentrations showed a very strong correlation, with values of 0.970 (p < 0.001) and 0.891 (p < 0.001), respectively. Linear mixed modelling revealed strong agreement between voriconazole concentrations in saliva and unbound plasma voriconazole concentrations, with a mean bias of -0.03 (95 % confidence interval -0.14 to 0.09; p = 0.60). For total concentrations below 10 mg/L, the mean ratio of saliva to total plasma voriconazole concentrations was 0.51 ± 0.08 (n = 63), which did not differ significantly (p = 0.76) from the unbound fraction of voriconazole in plasma of 0.49 ± 0.03 (n = 36).

CONCLUSIONS

Saliva can serve as a reliable alternative to plasma in voriconazole TDM, and it can easily be implemented in clinical practice.

Population Pharmacokinetics in China: The Dynamics of Intravenous Voriconazole in Critically Ill Patients with Pulmonary Disease

Pharmacokinetic research in China on the use of voriconazole in critically ill adult patients with different pulmonary diseases remains to be explored. This study evaluated the population pharmacokinetics of the use of voriconazole (VRC) in critically ill patients to determine covariate effects on VRC pharmacokinetics by NONMEM, which could further optimize VRC dosing in this population. A one-compartment model with first-order absorption and elimination best fit the data, giving 4.28 L/h clearance and 93.4 L volume of distribution of VRC. The model variability, described as an approximate percentage coefficient of interindividual variability in clearance and volume of distribution, was 72.94% and 26.50%, respectively. A significant association between Cmin and drug response or grade 2 hepatotoxicity was observed (p=0.002, <0.001, respectively, 1.5-4.0 µg/mL) via logistic multivariate regression. Monte Carlo simulations at 100, 150, 200, and 250 mg dosage predicted effectiveness at 45.99%, 99.76%, 98.76%, and 67.75% within the 1.5-4.0 µg/mL range, suggesting that a 150 or 200 mg intravenous dose twice daily is best suited to achieve the target steady state trough concentration range in critically ill patients with pulmonary disease.

Factors impacting unbound vancomycin concentrations in different patient populations

The unbound drug hypothesis states that only unbound drug concentrations are active and available for clearance, and highly variable results regarding unbound vancomycin fractions have been reported in the literature. We have determined the unbound vancomycin fractions in four different patient groups by a liquid chromatography tandem mass spectrometry (LC-MS/MS) method and identified factors that modulate vancomycin binding. We have further developed and validated a prediction model to estimate unbound vancomycin concentrations. Vancomycin (unbound and total) concentrations were measured in 90 patients in four different hospital wards (hematology [n = 33 samples], intensive care unit [ICU] [n = 51], orthopedics [n = 44], and pediatrics [age range, 6 months to 14 years; n = 18]) by a validated LC-MS/MS method. Multiple linear mixed model analysis was performed to identify patient variables that were predictive of unbound vancomycin fractions and concentrations. The variables included in the model were patient age, ward, number of coadministered drugs with high protein binding, kidney function (estimated glomerular filtration rate [determined by Chronic Kidney Disease Epidemiology Collaboration formula]), alpha-1-acid glycoprotein, albumin, total bilirubin, IgA, IgM, urea, and total vancomycin concentrations. In the pediatric cohort, the median unbound vancomycin fraction was 81.3% (range, 61.9 to 95.9%), which was significantly higher (P < 0.01) than the unbound fraction found in the three adult patient cohorts (hematology, 60.6% [48.7 to 90.6%]; ICU, 61.7% [47.0 to 87.6%]; orthopedics, 56.4% [45.9 to 78.0%]). The strongest significant predictor of the unbound vancomycin concentration was the total drug concentration, completed by albumin in the pediatric cohort and albumin and IgA in the adult cohorts. Validation of our model was performed with data from 13 adult patients. A mean difference of 0.3 mg/liter (95% confidence interval [CI], -1.3 to 0.7 mg/liter; R(2) = 0.99 [95% CI, 0.95 to 0.99]) between measured and calculated unbound vancomycin concentrations demonstrated that the predictive performance of our model was favorable. Unbound vancomycin fractions vary significantly between pediatric and adult patients. We developed a formula to estimate the unbound fraction derived from total vancomycin, albumin, and IgA concentrations in adult patients.

In vitro study of the variable effects of proton pump inhibitors on voriconazole

Voriconazole is a broad-spectrum antifungal agent used for the treatment of severe fungal infections. Maintaining therapeutic concentrations of 1 to 5.5 μg/ml is currently recommended to maximize the exposure-response relationship of voriconazole. However, this is challenging, given the highly variable pharmacokinetics of the drug, which includes metabolism by cytochrome P450 (CYP450) isotypes CYP2C19, CYP3A4, and CYP2C9, through which common metabolic pathways for many medications take place and which are also expressed in different isoforms with various metabolic efficacies. Proton pump inhibitors (PPIs) are also metabolized through these enzymes, making them competitive inhibitors of voriconazole metabolism, and coadministration with voriconazole has been reported to increase total voriconazole exposure. We examined the effects of five PPIs (rabeprazole, pantoprazole, lansoprazole, omeprazole, and esomeprazole) on voriconazole concentrations using four sets of human liver microsomes (HLMs) of different CYP450 phenotypes. Overall, the use of voriconazole in combination with any PPI led to a significantly higher voriconazole yield compared to that achieved with voriconazole alone in both pooled HLMs (77% versus 59%; P < 0.001) and individual HLMs (86% versus 76%; P < 0.001). The mean percent change in the voriconazole yield from that at the baseline after PPI exposure in pooled microsomes ranged from 22% with pantoprazole to 51% with esomeprazole. Future studies are warranted to confirm whether and how the deliberate coadministration of voriconazole and PPIs can be used to boost voriconazole levels in patients with difficult-to-treat fungal infections.