Tablets or oral suspension for posaconazole in lung transplant recipients? Consequences for trough concentrations of tacrolimus and everolimus.

AIMS: A new formulation of posaconazole (PCZ), delayed-release tablets (PCZ-tab), increases PCZ bioavailability and plasma trough concentrations (Cmin ) over those achieved with an oral suspension (PCZ-susp). PCZ is an inhibitor of cytochrome P450 3A4 and P-glycoprotein. We therefore investigated the impact of PCZ-tab treatment on blood Cmin and doses of tacrolimus (TAC) and everolimus (EVR). METHODS: Eighteen lung transplant patients receiving TAC (n = 13) or TAC + EVR (n = 5) between June 2015 and March 2016 were retrospectively included. Ten of these patients received both PCZ-tab and PCZ-susp (i.e. switched patients); the other 8 received only PCZ-tab. Plasma Cmin of PCZ (n = 64), blood Cmin of TAC (n = 299) and EVR (n = 80) were determined during routine therapeutic drug monitoring by liquid chromatography-tandem mass spectrometry. RESULTS: PCZ Cmin on PCZ-tab treatment (n = 48) was 2.5 times higher than that on PCZ-susp therapy (n = 16), for both PCZ patients (P < .0001) and for switched patients (P = .003). PCZ initiation, regardless of galenic form, increased TAC and EVR Cmin adjusted for dose (D), 3-fold and 3.5-fold, respectively (P < .0001 for both). PCZ-tab treatment was associated with a higher TAC Cmin /D (PCZ-tab vs PCZ-susp: 0.004 ± 0.004 L-1 vs 0.009 ± 0.006 L-1 , P < .0001) and lower TAC daily dose than PCZ-susp (PCZ-tab vs PCZ-susp: 1.08 ± 0.92 vs 2.32 ± 1.62 mg d-1 , P < .0001). EVR Cmin /D was higher and EVR dose tended to be lower on PCZ-tab than on PCZ-susp. CONCLUSION: The greater PCZ exposure achieved during PCZ-tab treatment increased drug-drug interactions with TAC and EVR, resulting in greater exposure, potentially exposing patients to higher risks of adverse effects.

Refining the therapeutic range of posaconazole and isavuconazole for efficient therapeutic drug monitoring using a bioassay approach.

Therapeutic drug monitoring (TDM) of antifungal triazole was recommended, except for isavuconazole (ISA) whose target trough concentrations (Cmin ) need to be specified. Concerning posaconazole (POS), tablet formulation results in higher exposure but no upper Cmin threshold has been yet proposed. We aimed to investigate the pharmacokinetic-pharmacodynamic relationship of POS and ISA, using a bioassay approach as surrogate marker of antifungal activity, in order to refine the therapeutic Cmin of both antifungals. A bioassay using a cellulose disk diffusion method was performed to determine the growth inhibition zone (GIZ) of POS and ISA on Aspergillus fumigatus and Candida parapsilosis (ISA only). GIZs of plasma from patients undergoing TDM for POS (n = 136) or ISA (n = 40) were determined. GIZs of plasma patients and antifungal Cmin were highly correlated for ISA (A. fumigatus: ρ = 0.942, P < 0.0001; C. parapsilosis: ρ = 0.949, P < 0.0001) and POS (ρ = 0.922, P < 0.0001), and these relationships were represented with a Michaelis-Menten model. Based on this modeling, the recommended thresholds of 0.7, 1, and 1.25 mg/L for the POS Cmin corresponded to 50.1, 55.2, and 59.1% of the maximal GIZ, respectively. We propose an upper threshold of 4.8 mg/L for the POS Cmin and a lower threshold of 2.0 mg/L for the Cmin of ISA, as they respectively corresponded to concentrations leading to 90% and 50% of the maximal GIZ on A. fumigatus. The determination of antifungal activity using this bioassay allowed refining target Cmin of POS and ISA, especially the upper threshold of POS (4.8 mg/L) and the lower threshold of ISA (2.0 mg/L).

Treatment by Posaconazole Tablets, Compared to Posaconazole Suspension, Does Not Reduce Variability of Posaconazole Trough Concentrations.

The delayed-release tablet formulation of posaconazole (POS-tab) results in higher plasma POS trough concentrations (Cmin) than the oral suspension (POS-susp), which raises the question of the utility of therapeutic drug monitoring (TDM). We aimed to compare the variability of the POS Cmin for the two formulations and identify determinants of the POS-tab Cmin and its variability. Demographic, biological, and clinical data from 77 allogeneic hematopoietic stem cell transplant patients (874 Cmin) treated with POS-tab (n = 41), POS-susp (n = 29), or both (n = 7) from January 2015 to December 2016 were collected retrospectively. Interpatient and within-subject coefficients of variation (CVs) of the Cmin adjusted to dose (D) were calculated for each formulation. Between-group comparisons were performed using a linear mixed effects model. The POS Cmin was higher for the tablet than for the suspension (median [25th-75th percentile]: 1.8 [1.2-2.4] mg/liter versus 1.2 [0.7-1.6] mg/liter, P < 0.0001). Interpatient CVs for the tablet and suspension were 60.8 versus 63.5% (P = 0.7), whereas within-subject CVs were 39.7 and 44.9%, respectively (P = 0.3). Univariate analysis showed that age and treatment by POS-tab were significantly and positively associated with the POS Cmin, whereas diarrhea was associated with a diminished POS Cmin Multivariate analysis identified treatment with POS-tab and diarrhea as independent factors of the POS Cmin, with a trend toward a lower impact of diarrhea during treatment with POS-tab (P = 0.07). Despite increased POS exposure with the tablet formulation, the variability of the POS Cmin was not significantly lower than that of the suspension. This suggests that TDM may still be useful to optimize tablet POS therapy.

Inflammation is a potential risk factor of voriconazole overdose in hematological patients.

Voriconazole (VRC) overdoses are frequent and expose patients at high risk of adverse effects. This case-control study performed in hematological patients who benefited from VRC therapeutic drug monitoring from January 2012 to December 2015 aimed to identify risk factors of VRC overdose. Pharmacogenetic, biological, and demographic parameters at the time of VRC trough concentration (Cmin ) were retrospectively collected from medical records. Cases (VRC overdose: defined by a VRC Cmin ≥ 4 mg/L; n = 31) were compared to controls (no VRC overdose: defined by VRC Cmin < 4 mg/L; n = 31) using nonparametric or chi-square tests followed by multivariable analysis. VRC overdoses were significantly associated with high CRP and bilirubin levels, intravenous administration, and age in univariable analysis. In contrast, the proportion of CYP genotypes (CYP2C19, CYP3A4, or CYP3A5, considered alone or combined in a combined genetic score) were not significantly different between patients who experienced a VRC overdose and those who did not. In multivariable analysis, the class of CRP level (defined by median CRP levels of 96 mg/L) was the sole independent risk factor of VRC overdose (P < 0.01). Patients with CRP levels > 96 mg/L) had a 27-fold (IC 95%: [6-106]) higher risk of VRC overdose than patients with CRP levels ≤ 96 mg/L. This study demonstrates that inflammatory status, assessed by CRP levels, is the main risk factor of VRC overdose in French hematological patients, whereas pharmacogenetic determinants do not appear to be involved.

Pharmacogenetics may influence the impact of inflammation on voriconazole trough concentrations.

How pharmacogenetics modulates the inhibitory effects of inflammation on voriconazole trough concentration (Cmin) remains unknown. In 29 recipients of allogeneic hematopoietic stem cell transplantation retrospectively studied, both a genetic score (which aggregated CYP2C19 and CYP3A genotypes) and inflammation significantly influenced voriconazole Cmin (n = 260). A trend toward (p = 0.03) a greater impact of inflammation in patients with the highest genetic score (corresponding to ultra-rapid metabolizers) was observed. Further researches are needed to confirm these data.

Alterations to mitochondrial fatty-acid use in skeletal muscle after chronic exposure to hypoxia depend on metabolic phenotype.

We investigated the effects of chronic hypoxia on the maximal use of and sensitivity of mitochondria to different substrates in rat slow-oxidative (soleus, SOL) and fast-glycolytic (extensor digitorum longus, EDL) muscles. We studied mitochondrial respiration in situ in permeabilized myofibers, using pyruvate, octanoate, palmitoyl-carnitine (PC), or palmitoyl-coenzyme A (PCoA). The hypophagia induced by hypoxia may also alter metabolism. Therefore, we used a group of pair-fed rats (reproducing the same caloric restriction, as observed in hypoxic animals), in addition to the normoxic control fed ad libitum. The resting respiratory exchange ratio decreased after 21 days of exposure to hypobaric hypoxia (simulated elevation of 5,500 m). The respiration supported by pyruvate and octanoate were unaffected. In contrast, the maximal oxidative respiratory rate for PCoA, the transport of which depends on carnitine palmitoyltransferase 1 (CPT-1), decreased in the rapid-glycolytic EDL and increased in the slow-oxidative SOL, although hypoxia improved affinity for this substrate in both muscle types. PC and PCoA were oxidized similarly in normoxic EDL, whereas chronic hypoxia limited transport at the CPT-1 step in this muscle. The effects of hypoxia were mediated by caloric restriction in the SOL and by hypoxia itself in the EDL. We conclude that improvements in mitochondrial affinity for PCoA, a physiological long-chain fatty acid, would facilitate fatty-acid use at rest after chronic hypoxia independently of quantitative alterations of mitochondria. Conversely, decreasing the maximal oxidation of PCoA in fast-glycolytic muscles would limit fatty-acid use during exercise.NEW & NOTEWORTHY Affinity for low concentrations of long-chain fatty acids (LCFA) in mitochondria skeletal muscles increases after chronic hypoxia. Combined with a lower respiratory exchange ratio, this suggests facility for fatty acid utilization at rest. This fuel preference is related to caloric restriction in oxidative muscle and to hypoxia in glycolytic one. In contrast, maximal oxidation for LCFA is decreased by chronic hypoxia in glycolytic muscle and can explain glucose dependence at exercise.

Infliximab quantitation in human plasma by liquid chromatography-tandem mass spectrometry: towards a standardization of the methods?

Infliximab (IFX) is a chimeric monoclonal antibody targeting tumor necrosis factor-alpha. It is currently approved for the treatment of certain rheumatic diseases or inflammatory bowel diseases. Clinical studies have suggested that monitoring IFX concentrations could improve treatment response. However, in most studies, IFX was quantified using ELISA assays, the resulting discrepancies of which raised concerns about their reliability. Here, we describe the development and validation of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for IFX quantification in human plasma. Full-length stable-isotope-labeled antibody (SIL-IFX) was added to plasma samples as internal standard. Samples were then prepared using Mass Spectrometry Immuno Assay (MSIA™) followed by trypsin digestion and submitted to multiple reaction monitoring (MRM) for quantification of IFX. The chromatographic run lasted 13 min. The range of quantification was 1 to 26 mg/L. For two internal quality controls spiked with 6 and 12 mg/L of IFX, the method was reproducible (coefficients of variation (CV%): 12.7 and 2.1), repeatable (intra-day CV%: 5.5 and 5.0), and accurate (inter-day and intra-day deviations from nominal values: +6.4 to +3.7 % and 5.5 to 9.2 %, respectively). There was no cross - contamination effect. Samples from 45 patients treated with IFX were retrospectively analyzed by LC-MS/MS and results were compared to those obtained with an in-house ELISA assay and the commercial Lisa Tracker® method. Good agreement was found between LC-MS/MS and in-house ELISA (mean underestimation of 13 % for in-house ELISA), but a significant bias was found with commercial ELISA (mean underestimation of 136 % for commercial ELISA). This method will make it possible to standardize IFX quantification between laboratories. Graphical Abstract Interassay comparison of the three methods: LC-MS/MS vs inhouse ELISA assay or vs Lisa Tracker® ELISA assays, Passing & Bablok (a) and Bland & Altman (b) for the comparison of LC-MS/MS vs in-house ELISA assay; Passing & Bablok

Low Cardiorespiratory Fitness is Partially Linked to Ventilatory Factors in Obese Adolescents.

AIM: To examine the role of ventilatory constraint on cardiorespiratory fitness in obese adolescents. METHODS: Thirty obese adolescents performed a maximal incremental cycling exercise and were divided into 2 groups based on maximal oxygen uptake (VO2peak): those presenting low (L; n = 15; VO2peak: 72.9 ± 8.6% predicted) or normal (N; n = 15; VO2peak: 113.6 ± 19.2% predicted) cardiorespiratory fitness. Both were compared with a group of healthy controls (C; n = 20; VO2peak: 103.1 ± 11.2% predicted). Ventilatory responses were explored using the flow volume loop method. RESULTS: Cardiorespiratory fitness (VO2peak, in % predicted) was lower in L compared with C and N and was moderately associated with the percent predicted forced vital capacity (FVC) (r = .52; p < .05) in L. At peak exercise, end inspiratory point was lower in L compared with N and C (77.4 ± 8.1, 86.4 ± 7.7, and 89.9 ± 7.6% FVC in L, N, and C, respectively; p < .05), suggesting an increased risk of ventilatory constraint in L, although at peak exercise this difference could be attributed to the lower maximal ventilation in L. CONCLUSION: Forced vital capacity and ventilatory strategy to incremental exercise slightly differed between N and L. These results suggest a modest participation of ventilatory factors to exercise intolerance.

Contribution of a Simple Bioassay in Effective Therapeutic Drug Monitoring of Posaconazole and Voriconazole.

BACKGROUND: With the constantly growing incidence of invasive fungal infections, any failure of antifungal treatment is worrying. Azole antifungals present high variability of their plasma trough concentrations (Cmin), justifying their therapeutic drug monitoring (TDM). The authors aimed to develop a simple bioassay to determine the in vitro growth inhibition diameter (ID) and to correlate this ID with Cmin in patients treated with voriconazole or posaconazole. METHODS: The bioassay determined the ID for Candida parapsilosis using a disk diffusion method. Calibration curves were built for posaconazole and voriconazole in water and in 45% plasma. ID was determined in plasma from patients currently undergoing TDM for posaconazole (n = 73) or voriconazole (n = 90). RESULTS: In water or plasma spiked with antifungals and patient samples, cubic regression between ID and Cmin gave coefficient of determination values of 0.997, 0.999, and 0.819, respectively, for posaconazole and 0.996, 0.990 and 0.925, respectively, for voriconazole (P < 0.001 for each curve). Calibration curves with or without plasma did not differ. For voriconazole, Cmin of 1 and 4.7 mg/L corresponded to 54% and 90% of maximal ID, respectively. For posaconazole, Cmin of 0.5, 0.7, and 1 mg/L corresponded to 26%, 40%, and 53% of maximal ID, respectively. CONCLUSIONS: Bioassay could be useful to better characterize the antifungal therapeutic range and brings additional information to the interpretation of TDM in patients for whom Cmin alone is insufficient to adjust the antifungal dosage.

Variability of voriconazole plasma concentrations after allogeneic hematopoietic stem cell transplantation: impact of cytochrome p450 polymorphisms and comedications on initial and subsequent trough levels.

Voriconazole (VRC) plasma trough concentrations (Cmin) are highly variable, and this could affect treatment efficacy and safety in patients undergoing allogeneic hematopoietic stem cell transplantation (AHSCT). We aimed to describe the intra- and interindividual variation of VRC Cmin throughout the course of VRC therapy and to identify the determinants of this variation. Clinical data, medications, and VRC Cmin (n = 308) of 33 AHSCT patients were retrospectively collected. Cytochrome P450 (CYP450) genotypes of CYP2C19, CYP3A4, and CYP3A5 patients were retrospectively determined before allografting, and a combined genetic score was calculated for each patient. The higher the genetic score, the faster the metabolism of the patient. The VRC Cmin inter- and intraindividual coefficients of variation were 84% and 68%, respectively. The VRC dose (D) was correlated to VRC Cmin (r = 0.412, P < 0.0001) only for oral administration. The administration route and the genetic score significantly affected the initial VRC Cmin. Considering oral therapy, patients with a genetic score of <2 had higher initial VRC Cmin/D than patients with a genetic score of >2 (P = 0.009). Subsequent VRC Cmin remained influenced by the genetic score (P = 0.004) but were also affected by pump proton inhibitor comedication (P < 0.0001). The high variability of VRC Cmin in AHSCT patients is partially explained by the route of administration, treatment with pump proton inhibitors, and the combined genetic score. This study suggests the interest in combined genetic score determination to individualize a priori the VRC dose and underlines the need for longitudinal therapeutic drug monitoring to adapt subsequent doses to maintain the VRC Cmin within the therapeutic range.

Simultaneous quantitation of azole antifungals, antibiotics, imatinib, and raltegravir in human plasma by two-dimensional high-performance liquid chromatography-tandem mass spectrometry.

High-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a standard analytical technique for therapeutic drug monitoring (TDM). A rapid LC-MS/MS method was developed for simultaneous quantitation of 3 antifungals and one active metabolite (posaconazole, voriconazole, itraconazole, and hydroxy-itraconazole), 5 antibiotics (daptomycin, ciprofloxacin, oxacillin, levofloxacin, and rifampicin), an antineoplastic agent (imatinib), and an antiretroviral (raltegravir) in human plasma. Protein precipitation of 10 µL of plasma with acetonitrile was used as a single-extraction procedure. After 2-dimensional LC, all drugs were quantified by electrospray ionization-triple quadrupole mass spectrometry by selected reaction monitoring detection in the positive mode. The method was validated per FDA recommendations including the study of extraction recovery (from 79.3% to 105.9%) and matrix effect via ion suppression/enhancement phenomenon. This method is precise (intra- and inter-assay coefficients of variation of 1.95-12.77%, 2.56-8.16% and 2.12-11.38% for low, medium and high levels of internal quality controls respectively) and accurate (intra- and inter-assay biases of 0.19-12.67%, 0.04 to -12.17% and 0.22-12.98% respectively). This method is an efficient tool for routine TDM and optimization of laboratory resource utilization.

Effect of chronic intermittent hypoxia on exercise adaptations in healthy subjects.

Reduced exercise tolerance has been reported in obstructive sleep apnea syndrome (OSAS) patients, although the associated hypertension, obesity and/or metabolic disorder may underlie this reduction. Therefore, we evaluated the effects of chronic intermittent hypoxia (CIH) in 12 healthy subjects on exercise capacity, cardio-respiratory responses, and substrate oxidation during maximal and sub-maximal exercise. Subjects were exposed to 30 cycles of hypoxia-reoxygenation per hour for 14 nights. Although exercise capacity was unaltered PETCO(2) was reduced and V˙E/V˙CO(2) increased during both maximal and submaximal exercise tests, indicating a hyperventilatory response. Maximal heart rate was lower and diastolic arterial blood pressure (DBP) was higher in the 1st min of recovery after submaximal exercise. Subjects reached maximal lipid oxidation at a higher power output and had decreased blood lactate for a given power output. This suggests that although the metabolic adaptations to CIH in healthy subjects may improve exercise performance, the cardio-pulmonary modifications are similar to those observed in OSAS patients and could limit exercise capacity.