Marie Antignac

Population pharmacokinetics of everolimus in cardiac recipients: comedications, ABCB1, and CYP3A5 polymorphisms.

Background: The aim of this study was, using routine drug monitoring data, to identify patient characteristics that may influence everolimus (EVE) pharmacokinetic parameters and to develop a population pharmacokinetic model to predict EVE whole blood concentrations in cardiac recipients. Methods: Fifty-nine patients were enrolled in the prospective study. Patient’s characteristics were recorded including biological covariates and treatments. CYP3A5 and ABCB1 polymorphisms were determined. Seven hundred seventy-five EVE blood samples were collected for routine drug monitoring. Population pharmacokinetic modeling was carried out using the nonlinear mixed-effects modeling program. Results were analyzed according to a 1-compartment pharmacokinetic model with linear absorption and elimination. The model was evaluated using a bootstrap method and a visual predictive check procedure. Results: The pharmacokinetic of EVE in cardiac recipients was best described by a 1-compartment model. Interindividual variability was best described by an exponential error model and residual error by a proportional plus additive error model. Estimation of EVE apparent clearance (3.33 ± 0.20 L/h) and apparent volume of distribution (146 ± 33 L) were in accordance with previously published data. Bilirubinemia and cyclosporine significantly influenced EVE clearance. Some covariates that were expected to influence EVE clearance, for example, ABCB1 and CYP3A5 polymorphisms, were not evidenced. No covariates influenced the volume of distribution of EVE. Conclusions: This study is the first population pharmacokinetic model of EVE in heart transplantation patients. It allows a better description of the pharmacokinetics of EVE. The present population pharmacokinetic model allows estimating a priori and a posteriori EVE concentrations in cardiac recipients and could limit the over and under drug exposure in this population.

Monitoring of tacrolimus concentrations in peripheral blood mononuclear cells: application to cardiac transplant recipients.

OBJECTIVES Despite the intensive therapeutic drug monitoring of tacrolimus (TAC) using trough whole blood concentrations, graft rejections occur in transplant recipient patients. Thus, other ways to monitor closely immunosuppressive treatments are necessary. A promising way of monitoring TAC treatments could be the measure of its concentrations inside of the lymphocyte cell. Whereas the pharmacokinetics of TAC in peripheral blood mononuclear cells (PBMCs) was evaluated in renal and liver transplant recipients, data regarding PBMC concentrations of TAC in cardiac transplant recipients are lacking. This study aimed, in cardiac transplant recipients: to validate a method for determination of TAC in PBMC, to investigate PBMC trough concentrations of TAC, and to evaluate their relationship with trough whole blood concentrations. DESIGN AND METHOD We developed and validated a High-performance-liquid-chromatography tandem mass-spectrometry method of TAC quantitation in PBMC. The method was then evaluated by determining TAC concentrations in PBMC of 24 cardiac transplant recipients. RESULTS Twenty-four patients were prospectively included in the study. Tacrolimus PBMC concentrations displayed a large inter-individual pharmacokinetic variability (CV=71.4%) in the cohort. A lack of correlation between TAC whole blood trough concentrations and TAC trough concentrations in PBMCs was found (r=0.259; p=0.183). CONCLUSION Further studies should be implemented to evaluate the correlation between TAC concentrations in PBMC and clinical outcomes in cardiac transplant recipients to allow concluding whether monitoring TAC concentrations in PBMC is a good tool to prevent graft rejection in cardiac recipients.

Impact of Extracorporeal Membrane Oxygenation and Continuous Venovenous Hemodiafiltration on the Pharmacokinetics of Oseltamivir Carboxylate in Critically Ill Patients With Pandemic (h1n1) Influenza

Purpose The neuraminidase inhibitor oseltamivir is a recommended treatment for influenza A (H1N1) infection. In rare cases, some patients develop influenza-associated multiple organ failures, requiring rescue therapies such as extracorporeal membrane oxygenation (ECMO) or continuous venovenous hemodiafiltration (CVVHDF). This study was designed to evaluate the impact of ECMO and CVVHDF on the pharmacokinetics of oseltamivir carboxylate (OC) in critically ill patients with pandemic (H1N1) influenza treated with oseltamivir. Patients and Methods Seven critically ill patients on venovenous ECMO for severe pandemic (H1N1) influenza associated with acute respiratory distress syndrome were treated with various doses of oseltamivir (75 or 150 mg twice daily). Because of acute kidney injury, 3 of them also received CVVHDF. OC, the active form of oseltamivir, was quantified in plasma, and main pharmacokinetic parameters were determined. Results OC Cmax (1029 ± 478 ng/mL) and area under the curve (9.00 ± 4.52 mcg·h/mL) for patients on ECMO with preserved renal function were comparable with those of healthy volunteers or noncritically ill patients. Patients both on ECMO and CVVHDF had 4-to 5-fold higher OC Cmax and area under the curve. Conclusions ECMO by itself did not impact on the pharmacokinetics of OC. However, the drug accumulated in the plasma of patients on ECMO who also received CVVHDF for renal failure. Based on these results, we recommend that oseltamivir dosage should be decreased and plasma levels of OC be monitored in patients receiving CVVHDF because of acute kidney injury.

Everolimus quantification in peripheral blood mononuclear cells using ultra high performance liquid chromatography tandem mass spectrometry

A reliable ultra high performance liquid chromatography tandem mass spectrometry method has been developed for the determination of everolimus in human peripheral blood mononuclear cells (PBMCs). Protein precipitation was used for sample preparation. Analysis was performed on an UPLC Waters Acquity system. Chromatography was carried out using a cartridge column MassTrak TDM C18 (2.1×10 mm) with 0.1% formic acid and 2 mM of ammonium acetate in water and 0.1% formic acid and 2mM of ammonium acetate in methanol mixture as a mobile phase delivered at a flow rate of 0.4 mL/min in gradient mode. The assay was linear over a range of 0-12.5 ng/mL. The analysis of quality control samples at 2.5, 5.0 and 10.0 ng/mL demonstrated good precision with relative standard deviation of less than 15%. Recoveries at concentrations of 2.5, 5.0 and 10.0 ng/mL were all greater than 83%. The method was successfully applied to the analysis of everolimus in PBMCs from blood samples of transplant recipients.

Liquid chromatography with tandem mass spectrometry for the simultaneous identification and quantification of cardiovascular drugs applied to the detection of substandard and falsified drugs

The counterfeiting of pharmaceuticals has been detected since about 1990 and has alarmingly continued to pick up steam. We have been recently involved in an evaluation program of some of the most commonly prescribed cardiovascular drugs in Africa, for analysing an important number of tablets or capsules obtained from different places in seven African countries. A reversed-phase high-performance liquid chromatography with tandem mass spectrometry method was developed and validated to simultaneously control the identity and the quantity of acenocoumarol, amlodipine, atenolol, captopril, furosemide, hydrochlorothiazide and simvastatin in tablets. Their separation was performed on a Kinetex® C(18) (100 mm × 2.1 mm inside diameter, 2.6 μm) column using a gradient elution of 20 mM ammonium formate buffer and acetonitrile (90:10 10:90 v/v) at a flow rate of 0.5 mL/min. The analytes were detected using electrospray ionisation tandem mass spectrometry in both positive and negative modes with multiple reaction monitoring. Tandem mass spectrometry fragmentation patterns of captopril, furosemide and acenocoumarol, up to now not detailed in the literature, were also studied to assist in the selection of the most relevant transitions towards the objectives. The developed method was validated as per International Conference on Harmonisation guidelines with respect to specificity, linearity, trueness, precision, limits of detection and quantification. It has been successfully applied to the control of oral forms of seven cardiovascular drugs collected in African countries.

Opportunity to monitor immunosuppressive drugs in peripheral blood mononuclear cells: where are we and where are we going?

Immunosuppressive (IS) drugs are now widely used as preventive treatments of allograft rejection in transplantation. Therapeutic drug monitoring (TDM) using trough whole blood concentrations is usually warranted and therapeutic range is recommended to ensure efficacy and prevent toxicity from these drugs. This intensive TDM reduces acute graft rejection but despite this management, the acute rejection rate still remains high in the first two years post-transplantation and few improvements have been made recently to reduce this rate. Moreover, in some patients, acute rejections occur despite adequate trough whole blood IS concentrations. Thus, other ways to monitor immunosuppressive drug effects have to be investigated. As lymphocyte cells are the site of action of IS drugs and so the effect compartment of the drug, monitoring IS drugs in lymphocytes, or for practical reasons in peripheral blood mononuclear cells (PBMC), could be more relevant than standard TDM. The aim of this paper is to review the recent work conducted on the advantages of monitoring IS drugs in PBMC, particularly for calcineurin inhibitors and mammalian target of rapamycin (m-TOR) inhibitors, from an analytical point of view as well as a clinical point of view.

Pharmacokinetics and pharmacodynamics of tacrolimus in liver transplant recipients: inside the white blood cells

OBJECTIVES Despite improvements in patient management and extensive use of therapeutic drug monitoring (TDM), the rate of acute cellular rejection (ACR) remains high in patients treated with tacrolimus (TAC). Moreover, some patients experienced ACR while their whole-blood (WB) concentrations were maintained within the therapeutic range meaning that TDM in WB misrepresents the drug effect. Thus, monitoring TAC directly inside of its effect compartment (intracellular concentrations) or monitoring directly the inhibitory effect on the target protein (calcineurin activity) could be more relevant. The aim of the present study was to explore, in 10 de novo liver transplant recipients, the relationship between TAC whole-blood concentrations, TAC intracellular concentrations and TAC-induced intracellular calcineurin inhibition at day 1 and day 7 after treatment initiation. DESIGN AND METHODS Prospective monocentric observational pharmacokinetic (WB and intracellular concentrations)-pharmacodynamic (calcineurin activity) study. RESULTS Full intracellular TAC pharmacokinetic as well as calcineurin activity steady-state profiles is presented in the study. The main result of this study is the lack of relationship between TAC pharmacokinetics (WB and leukocytes) and calcineurin activity in leukocytes at day 1 and day 7 after the graft implantation. CONCLUSIONS Drug monitoring of TAC intracellular concentrations and determination of the calcineurin activity are among future potential biomarkers of acute rejection in transplant recipients. A better knowledge of the relationship between TAC whole blood and intracellular concentrations and calcineurin activity appears necessary before planning clinical trials to evaluate their potential interest as predictive biomarkers.

Quality Assessment of 7 Cardiovascular Drugs in 10 Sub-Saharan Countries: The SEVEN Study

Quality Assessment of 7 Cardiovascular Drugs in 10 Sub-Saharan Countries: The SEVEN Study Substandard and falsified medicines pose a serious threat to patient safety and public health.1 Studies on the quality of drugs have focused mainly on antimicrobial agents, such as antiretroviral therapy (for human immunodeficiency virus) and antimalarial medications.2 Although cardiovascular disease kills millions of Africans,3 to our knowledge, little published research has explored the quality of essential cardiovascular disease medicines to date. We therefore performed a quality assessment of 7 commonly used cardiac drugs (ie, an anticoagulant drug, a statin, and 5 antihypertensive drugs) in 10 countries of sub-Saharan Africa.

Socioeconomic Status and Hypertension Control in Sub-Saharan AfricaNovelty and Significance: The Multination EIGHT Study (Evaluation of Hypertension in Sub-Saharan Africa)

Systemic hypertension is a rapidly growing epidemic in Africa. The role of socioeconomic status on blood pressure control has not been well studied in this part of the world. We, therefore, aimed to quantify the association of socioeconomic status both at the individual and at the country level with blood pressure control in Sub-Saharan Africa. We conducted a cross-sectional survey in urban clinics of 12 countries, both low income and middle income, in Sub-Saharan Africa. Standardized blood pressure measures were made among the hypertensive patients attending the clinics. Blood pressure control was defined as blood pressure <140/90 mm Hg, and hypertension grades were defined according to the European Society of Cardiology guidelines. A total of 2198 hypertensive patients (58.4±11.8 years; 39.9% men) were included. Uncontrolled hypertension was present in 1692 patients (77.4%), including 1044 (47.7%) with ≥grade 2 hypertension. The proportion of uncontrolled hypertension progressively increased with decreasing level of patient individual wealth, respectively, 72.8%, 79.3%, and 81.8% (P for trend, <0.01). Stratified analysis shows that these differences of uncontrolled hypertension according to individual wealth index were observed in low-income countries (P for trend, 0.03) and not in middle-income countries (P for trend, 0.26). In low-income countries, the odds of uncontrolled hypertension increased 1.37-fold (odds ratio, 1.37 [0.99–1.90]) and 1.88-fold (odds ratio, 1.88 [1.10–3.21]) in patients with middle and low individual wealth as compared with high individual wealth. Similarly, the grade of hypertension increased progressively with decreasing level of individual patient wealth (P for trend, <0.01). Strategies for hypertension control in Sub-Saharan Africa should especially focus on people in the lowest individual wealth groups who also reside in low-income countries.

Letter by Antignac et al Regarding Article “Access to Medications for Cardiovascular Diseases in Low- and Middle-Income Countries”

We read with great interest the article by Wirtz et al,1 which presents an overview on access to cardiovascular medications in low- and middle-income countries. It is noteworthy that, among the 5 health system dimensions of access described, the first 4 have been well researched through large multination studies. Low availabilit y of cardiovascular disease medicines has been well reported; a fairly recent meta-analysis of surveys from 36 countries assessed access to different classes of cardiovascular medicines.1 Several peer-reviewed publications have also reported on the affordability of cardiovascular …