Anne Hulin

Introduction: Recent publications suggest potential benefits from statins as a preventive or adjuvant therapy in sepsis. Whether ongoing statin therapy should be continued or discontinued in patients admitted in the intensive care unit (ICU) for sepsis is open to question. Methods: We retrospectively compared patients with severe sepsis and septic shock in whom statin therapy had been discontinued or continued. The primary endpoint was the number of organ failure-free days at day 14. Secondary end-points included hospital mortality and safety. The association of statin continuation with outcome was evaluated for crude analysis and after propensity score matching and adjustment. We also measured plasma atorvastatin concentrations in a separate set of ICU septic patients continuing the drug. Results: Patients in whom statin therapy had been continued in the ICU (n = 44) had significantly more organ failure-free days (11 [6–14] vs. 6 [0-12], mean difference of 2.34, 95%CI from 0.47 to 5.21, P = 0.03) as compared to others (n = 32). However, there were important imbalances between groups, with more hospital-acquired infections, more need for surgery before ICU admission, and a trend towards more septic shock at ICU admission in the discontinuation group. The significant association of statin continuation with organ failure free days found in the crude analysis did not persist after propensity-matching or multivariable adjustment: beta coefficients [95% CI] of 2.37 [-0.96 to 5.70] (P = 0.20) and 2.24 [-0.43 to 4.91] (P = 0.11) respectively. We found particularly high pre-dose and post-dose atorvastatin concentrations in ICU septic patients continuing the drug. Conclusions: Continuing statin therapy in ICU septic patients was not associated with reduction in the severity of organ failure after matching and adjustment. In addition, the very high plasma concentrations achieved during continuation of statin treatment advocates some caution.

Background: Hydroxyurea (HU) is the first approved pharmacological treatment of sickle cell anemia (SCA). The objectives of this study were to develop population pharmacokinetic(PK)-pharmacodynamic(PD) models for HU in order to characterize the exposure-efficacy relationships and their variability, compare two dosing regimens by simulations and develop some recommendations for monitoring the treatment. Methods: The models were built using population modelling software NONMEM VII based on data from two clinical studies of SCA adult patients receiving 500-2000 mg of HU once daily. Fetal hemoglobin percentage (HbF%) and mean corpuscular volume (MCV) were used as biomarkers for response. A sequential modelling approach was applied. Models were evaluated using simulation-based techniques. Comparisons of two dosing regimens were performed by simulating 10000 patients in each arm during 12 months. Results: The PK profiles were described by a bicompartmental model. The median (and interindividual coefficient of variation (CV)) of clearance was 11.6 L/h (30%), the central volume was 45.3 L (35%). PK steady-state was reached in about 35 days. For a given dosing regimen, HU exposure varied approximately fivefold among patients. The dynamics of HbF% and MCV were described by turnover models with inhibition of elimination of response. In the studied range of drug exposures, the effect of HU on HbF% was at its maximum (median I_max was 0.57, CV was 27%); the effect on MCV was close to its maximum, with median value of 0.14 and CV of 49%. Simulations showed that 95% of the steady-state levels of HbF% and MCV need 26 months and 3 months to be reached, respectively. The CV of the steady-state value of HbF% was about 7 times larger than that of MCV. Simulations with two different dosing regimens showed that continuous dosing led to a stronger HbF% increase in some patients. Conclusions: The high variability of response to HU was related in part to pharmacokinetics and to pharmacodynamics. The steady-state value of MCV at month 3 is not predictive of the HbF% value at month 26. Hence, HbF% level may be a better biomarker for monitoring HU treatment. Continuous dosing might be more advantageous in terms of HbF% for patients who have a strong response to HU. Trial Registration: The clinical studies whose data are analysed and reported in this work were not required to be registered in France at their time. Both studies were approved by local ethics committees (of Mondor Hospital and of Kremlin-Bicetre Hospital) and written informed consent was obtained from each patient.

Our objectives were (1) to study the HU metabolism via human cytochromes and (2) to test if HU is a substrate of P‐gp. HU metabolism was investigated by determining the appearance of urea and HU decreasing upon incubation with human liver microsomes. Quantification was determined using HPLC coupled with UV‐detection at 449 nm. Our method was linear between 5 and 1000 μm, precise (coefficients of variation ranging from 1.7 to 9.9%), accurate (97.7–103.9%). The limit of quantification was 7 μm. The ATPase activity of human P‐gp membranes was determined by measuring inorganic phosphate liberation. HU and urea measurements in microsomes were not different between 0 and 60 min whatever HU concentration used from 30 to 300 μm. The presence of NADPH in the medium has no effect on HU and urea measurements. In the absence of verapamil, the ATPase activity was unaffected by HU at concentrations of 10, 30, 100 and 300 μm. HU is unlikely to cause clinically relevant drug interactions with the substrates of these enzymes/transporters. However, it will be necessary to validate these in vitro data in patients with sickle cell anemia to evaluate the impact of genetic polymorphisms of these enzymes in a black population.

Background: Tacrolimus and cyclosporin inhibits the activity of calcineurin, a serine/threonine phosphatase that is involved in many physiological and pathological pathways. However, the baseline calcineurin phosphatase activity (CPA) measured before the transplant is unknown. In this study, we determine baseline CPA in liver transplant (LT) candidates and explore some factors that might modify it.Patients and methods: Thirty‐two consecutive LT candidates (25 men, seven women, average age 53.4 years) were included. Seven millilitres of whole blood was collected from each patient. CPA was determined in lymphocytes quantifying a dephosphorylated peptide phosphorylated previously (D‐L‐D‐V‐P‐I‐P‐G‐R‐F‐D‐R‐R‐V‐S‐V‐A‐A‐E) by high‐performance liquid chromatography. The relationship between CPA and the quantitative variables was tested according to Pearson's correlation. A two‐way analysis of variance was performed to test the independent role of categorical parameters in CPA.Results: The median CPA was significantly lower in LT candidates than in healthy volunteers [179.2 (146.9–226.3) vs 247.8 (220.9–292.5) pmol/min/10⁶ peripheral blood mononuclear cell (PBMC), respectively, P=0.0002]. CPA was also significantly lower in alcoholic cirrhosis (152.2 vs 211.1 pmol/min/10⁶ PBMC, P=0.04) and in the presence of hepatocellular carcinoma (HCC) (152.0 vs 213.5 pmol/min/10⁶ PBMC, P=0.0074) compared with other liver diseases. A two‐way analysis of variance showed that these parameters were independently associated with lower CPA (P=0.05 for alcohol and P=0.0056 for HCC respectively).Conclusion: This pilot study showed a lower CPA in patients with AC and HCC. This phenomenon may contribute towards lowering the risk of acute rejection in these patients after LT and, on the other hand, may increase the risk of de novo cancers.

During the early post-transplantation period, the limitations of monitoring current tacrolimus dose with classic pharmacokinetics (PK) have been demonstrated in liver-transplant recipients. Evaluation of the pharmacodynamics (PD) using calcineurin activity (CNA) has been proposed to optimize tacrolimus dosing. The aim of the present study was to determine the time of maximal inhibition of CNA, to explore the relation between exposure to tacrolimus and CNA, and to analyze its variability. Blood was drawn from 14 patients 0, 2, 3, 4, 6, and 9 hours after tacrolimus intake on post-transplantation days 8, 21, and 90 to measure blood tacrolimus concentrations using the EMIT 2000 assay and CNA in peripheral blood mononuclear cells. Tacrolimus and CNA data were obtained for 33 blood-sample collection sessions and analyzed using a population approach. Three models were built to describe tacrolimus PK, CNA kinetics, and the relationships between the area under the CNA-time curve (AUC_12effCNA) and AUC_12Tacrolimus or C_{minTacrolimus}. Coagulation factor V and whole/split liver graft were identified as covariates influencing tacrolimus clearance. Indeed, apparent tacrolimus clearance rose by 14% when factor V increased by 10% and was threefold higher in patients with whole-liver grafts. The median maximal inhibition of CNA was reached 4 hours after tacrolimus intake on days 8, 21, and 90 and represented an 18% drop in CNA compared with activity at drug intake. The variability of the PK-PD relationship was minimal when using AUC_12Tacrolimus. The large variability of the PD parameters (coefficient of variation was 89%) that linked AUC_12effCNA to AUC_12Tacrolimus indicates that monitoring tacrolimus concentrations may not be adequate to control CNA. Measuring CNA in peripheral blood mononuclear cells 4 hours after tacrolimus intake during the first 3 months after liver transplantation could be a means to improve tacrolimus monitoring and thereby avoid acute graft-rejection episodes.