Jean Marc Tréluyer

Pregnancy-Related Effects on Tenofovir Pharmacokinetics: a Population Study with 186 Women

ABSTRACT According to the European AIDS Clinical Society, tenofovir disoproxil fumarate can be used in HIV-infected pregnant women if started prior to pregnancy, although no data are available on the pharmacokinetics of tenofovir (TFV) during pregnancy. The aim of this study was to describe TFV pharmacokinetics in HIV-infected women and to evaluate the effect of pregnancy on TFV disposition. Samples were collected according to a therapeutic drug monitoring in 186 women, including 46 pregnant women treated with TFV and retrospectively analyzed by a population approach. TFV pharmacokinetics were ascribed to an open two-compartment model with linear absorption and elimination. The mean population parameter estimates (between-subject variability) were as follows: absorption rate constant, 0.56 h−1; elimination clearance, 59.9 liters h−1 (0.436); central volume of distribution, 552 liters (1.96); intercompartmental clearance, 172 liters/h; and peripheral volume of distribution, 1,390 liters. Pregnant women had a 39% higher apparent clearance compared to nonpregnant women. Apparent clearance significantly decreased with age. In order to obtain an exposure similar to the known exposure in adults and guarantee similar trough concentrations (Cmin) as observed in adults, an increase in the TFV dose should be considered for women from the second trimester to delivery.

Placental Transfer of Maraviroc in an Ex Vivo Human Cotyledon Perfusion Model and Influence of ABC Transporter Expression

ABSTRACT Nowadays, antiretroviral therapy is recommended during pregnancy to prevent mother-to-child transmission of HIV. However, for many antiretroviral drugs, including maraviroc, a CCR5 antagonist, very little data exist regarding placental transfer. Besides, various factors may modulate this transfer, including efflux transporters belonging to the ATP-binding cassette (ABC) transporter superfamily. We investigated maraviroc placental transfer and the influence of ABC transporter expression on this transfer using the human cotyledon perfusion model. Term placentas were perfused ex vivo for 90 min with maraviroc (600 ng/ml) either in the maternal-to-fetal (n = 10 placentas) or fetal-to-maternal (n = 6 placentas) direction. Plasma concentrations were determined by ultra performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Fetal transfer rates (FTR) and clearance indexes (CLI) were calculated as ratios of fetal to maternal concentrations at steady state (mean values between 30 and 90 min) and ratios of FTR of maraviroc to that of antipyrine, respectively. ABC transporter gene expression levels were determined by quantitative reverse transcription (RT)-PCR and ABCB1 protein expression by Western blotting. For the maternal-to-fetal direction, the mean FTR and CLI were 8.0% ± 3.0 and 0.26 ± 0.07, respectively, whereas the mean CLI was 0.52 ± 0.23 for the fetal-to-maternal direction. We showed a significant inverse correlation between maraviroc CLI and ABCC2, ABCC10, and ABCC11 placental gene expression levels (P < 0.05). To conclude, we report a low maraviroc placental transfer probably involving ABC efflux transporters and thus in all likelihood associated with a limited fetal exposition. Nevertheless, these results would need to be supported by in vivo data obtained from paired maternal and cord blood samples.

Parental comprehension of the benefits/risks of first-line randomised clinical trials in children with solid tumours: a two-stage cross-sectional interview study

Objectives To analyse the parental understanding of informed consent information in first-line randomised clinical trials (RCTs) including children with malignant solid tumours and to assess parents’ needs for decision-making. Design Observational prospective study. Setting 3 paediatric oncology centres in the Parisian region in France. Participants 53 parents were approached to participate in a RCT for their child with malignant solid tumour, over a 1-year period. 40 parents have been interviewed in our study. Primary and secondary outcome measures Parental understanding of information in RCTs, parents’ needs for decision-making. Parents were questioned by a psychologist, independent of the paediatric oncology teams, using a semidirected interview, 1 (M1) and 6 months (M6) after the consent was sought. Results 18 parents (45%) did not understand the concept of randomisation. Half of the parents could explain neither the aim of the clinical trial nor the potential benefit to their child of inclusion. 35 parents (87.5%) expressed very few specific risks related to the trial. Being mostly French-speaking (p=0.03) and the reading of the information sheet by the parents (p=0.0025) improved their understanding. The parental comprehension did not differ between M1 and M6. The principal factors underlying their decision were confidence in the medical team (39%), wish to access to the best treatment (37%) and the best quality of life (37%). Conclusions Despite medical explanations, parents have limited knowledge in some areas in first-line RCTs and improvements of information process are required. The risks specific to the randomised trial are underestimated by parents and the unproven nature of the treatment is not well-known or understood.

Pregnancy-Related Effects on Lamivudine Pharmacokinetics in a Population Study with 228 Women

ABSTRACT The aim of this study was to describe lamivudine (3TC) pharmacokinetics (PK) in HIV-infected nonpregnant and pregnant women and their fetuses. Samples were collected according to therapeutic drug monitoring from 228 women treated with lamivudine and retrospectively analyzed by a population approach. The samples were also collected from cord blood and amniotic fluid at birth. Lamivudine pharmacokinetics were ascribed to an open two-compartment model with linear absorption and elimination. Mean population parameter estimates (intersubject variability) for women were an absorption rate constant of 1.04 h−1, an elimination clearance rate of 23.6 (0.266) liters · h−1, a central volume of distribution of 109 (0.897) liters, an intercompartmental clearance rate of 6.7 liters/h, and a peripheral volume of distribution of 129 liters. A fetal compartment was linked to maternal circulation by mother-to-cord (or fetus) and cord-to-mother rate constants of 0.463 h−1 and 0.538 h−1, respectively. The amniotic fluid compartment was connected to the fetal compartment with an elimination rate constant of 0.163 h−1 and a fixed-constant swallowing flow. The placental transfer expressed as fetal-to-maternal area under the concentration-time curve (AUC) ratio was 0.86, and the lamivudine amniotic fluid accumulation, expressed as the amniotic fluid-to-fetal AUC ratio, was 2.9. Pregnant women had a 22% higher apparent clearance than nonpregnant and parturient women; however, this increase did not lead to subexposure and should not require a dosage adjustment.

Joint Population Pharmacokinetic Analysis of Zidovudine, Lamivudine, and Their Active Intracellular Metabolites in HIV Patients

ABSTRACT The population pharmacokinetic parameters of zidovudine (AZT), lamivudine (3TC), and their active intracellular metabolites in 75 naïve HIV-infected patients receiving an oral combination of AZT and 3TC twice daily as part of their multitherapy treatment in the COPHAR2-ANRS 111 trial are described. Four blood samples per patient were taken after 2 weeks of treatment to measure drug concentrations at steady state. Plasma AZT and 3TC concentrations were measured in 73 patients, and among those, 62 patients had measurable intracellular AZT-TP and 3TC-TP concentrations. For each drug, a joint population pharmacokinetic model was developed and we investigated the influence of different covariates. We then studied correlations between the mean plasma and intracellular concentrations of each drug. A one-compartment model with first-order absorption and elimination best described the plasma AZT concentration, with an additional compartment for intracellular AZT-TP. A similar model but with zero-order absorption was found to adequately described concentrations of 3TC and its metabolite 3TC-TP. The half-lives of AZT and 3TC were 0.81 h (94.8%) and 2.97 h (39.2%), respectively, whereas the intracellular half-lives of AZT-TP and 3TC-TP were 10.73 h (69%) and 21.16 h (44%), respectively. We found particularly a gender effect on the apparent bioavailability of AZT, as well as on the mean plasma and intracellular concentrations of AZT, which were significantly higher in females than in males. Relationships between mean plasma drug and intracellular metabolite concentrations were also highlighted both for AZT and for 3TC. Simulation with the model of plasma and intracellular concentrations for once- versus twice-daily regimens suggested that a daily dosing regimen with double doses could be appropriate.

Challenges regarding analysis of unbound fraction of highly bound protein antiretroviral drugs in several biological matrices: lack of harmonisation and guidelines

The unbound drug concentration in plasma is usually considered the only active fraction; thus the binding of a drug to a protein limits its pharmacological actions. This is of special importance for those highly bound drugs. Therefore, binding studies can be of great utility for those drugs where relationship between free and total drug concentration is variable among patients, or it can be altered by some condition or disease, or even by interactions with other drugs. However, there is a lack of validation guidelines for the determination of unbound concentrations. Antiretroviral drugs (ARVs), protease inhibitors (PIs), efavirenz and nevirapine are highly bound to proteins. Here, we present a review on the overall methods for the study of unbound fractions of highly bound plasma protein ARVs. We also provide a critical evaluation of the methods applied, their differences and the main points to be controlled and validated.

Efavirenz concentrations and probability of HIV replication in children

In 188 HIV-infected children receiving efavirenz, a lower mid-dose (C12) was associated with a higher risk of HIV-1 viral load >400 copies/mL (P = 0.03). Simulations for a normalized population receiving US Food and Drug Administration weight-band dosing predicted that 15% of children would have a C12 below target threshold (<1.0 mg/L) with a 23% risk of viral replication.

Association between genetic polymorphisms and platinum-induced ototoxicity in children

Platinum is extensively used in the treatment of several childhood cancers. However, ototoxicity is one of the most notable adverse effects, especially in children. Several studies suggest that genetics may predict its occurrence. Here, polymorphisms associated with platinum-induced ototoxicity were selected from the literature and were investigated in a pediatric population treated with platinum-based agents. In this retrospective study, patients treated with cisplatin and/or carboplatin were screened. The patients with pre- and post-treatment audiogram (Brock criteria) available were included. We selected polymorphisms that have previously been associated with cisplatin ototoxicity with a minor allele frequency ≥30%. Deletion of GSTM1 and GSTT1, rs1799735 (GSTM3), rs1695 (GSTP1), rs4880 (SOD2), rs2228001 (XPC), rs1799793 (XPD) and rs4788863 (SLC16A5) were investigated. Data of one hundred and six children matching the eligible criteria were analyzed. Thirty-three patients (31%) developed ototoxicity (with a Brock grade ≥2). The probability of hearing loss increased significantly in patients carrying the null genotype for GSTT1 (P = 0.03), A/A genotype at rs1695 (P = 0.01), and C/C genotype at rs1799793 (P = 0.008). We also showed an association of the cumulative doses of carboplatin with cisplatin ototoxicity (P <0.05). To conclude, deletion of GSTT1, rs1695 and rs1799793 may constitute potential predictors of platinum-induced ototoxicity.

A Population Pharmacokinetic/Pharmacodynamic Model Predicts Favorable HDL Cholesterol Changes Over the First 5 Years in Children Treated With Current Efavirenz‐Based Regimens

Efavirenz use is associated with changes in cholesterol concentrations, but it is unclear whether this effect is related to drug concentrations. Using efavirenz and cholesterol plasma concentrations measured in 87 antiretroviral‐naive children in Thailand, we assessed indirect response models to describe the evolution of high‐ and low‐density lipoprotein (HDL, LDL) cholesterol concentrations in relation to efavirenz plasma concentrations over time where efavirenz was assumed to either stimulate cholesterol production or inhibit its elimination. Simulations of cholesterol evolution for children with different average efavirenz concentrations (Cav) according to their assumed status of “fast” or “slow” metabolizers of efavirenz were performed. At treatment initiation, childrens median (interquartile range, IQR) age was 8 years (5 to 10), body mass index z‐score 0.01 (–1.05 to 1.44), HDL 31 mg/dL (24 to 44), and LDL 83 mg/dL (69 to 100). Median (IQR) efavirenz Cav was 1.7 mg/L (1.3 to 2.1) during the period of observation. The best model describing the evolution of HDL and LDL cholesterol concentrations over time assumed that efavirenz inhibited their elimination. HDL concentrations increase over 5 years, whereas LDL concentrations increased only during the first 4 months and then returned to baseline levels afterward. Simulations predicted that, after 3 years, HDL would increase to 63 mg/dL in “fast” metabolizers and 97 mg/dL in “slow” metabolizers of efavirenz. The population pharmacokinetic‐pharmacodynamic (PK‐PD) model shows that favorable HDL cholesterol changes can be expected in children with current efavirenz dosing guidelines over 5 years of treatment.

Contribution of different antiretroviral regimens containing zidovudine, lamivudine and ritonavir-boosted lopinavir on HIV viral load reduction during pregnancy.

BACKGROUND Antiretroviral (ARV) regimens used for the prevention of mother-to-child transmission of HIV have evolved over time. We evaluated the contribution of different ARV regimens on the reduction of the plasma HIV RNA viral load (VL) during pregnancy. METHODS A total of 1,833 VL measurements from ARV-naive pregnant women participating in perinatal prevention trials in Thailand were included. Women received either zidovudine (ZDV) monotherapy, ZDV plus lopinavir/ritonavir (LPV/r), or ZDV plus lamivudine (3TC) plus LPV/r. VL time-course during pregnancy was described as a function of pretreatment VL and treatment duration using an Emax non-linear mixed-effect model. VL reduction and median time to achieve a VL<50 copies/ml were estimated for each regimen. RESULTS Among 745 women, 279 (37%), 145 (20%) and 321 (43%) received ZDV monotherapy, ZDV+LPV/r and ZDV+3TC+LPV/r, respectively. The predicted VL reduction from baseline to delivery after a median of 10 weeks of treatment were 0.5, 2.7 and 2.9 log10 copies/ml with ZDV monotherapy, ZDV+LPV/r and ZDV+3TC+LPV/r, respectively. At delivery, 1%, 57% and 63% of women receiving ZDV monotherapy, ZDV+LPV/r or ZDV+3TC+LPV/r had a VL<50 copies/ml. The addition of 3TC to ZDV+LPV/r reduced the time to achieve a VL<50 copies/ml and the higher the pretreatment VL, the larger the effect 3TC had on reducing the time to VL<50 copies/ml. CONCLUSIONS The addition of 3TC to ZDV+LPV/r was associated with a slight further VL reduction but the time to reach a VL<50 copies/ml was shorter. This beneficial effect of 3TC is crucial for prevention of mother-to-child transmission in women who receive ARVs late and with high pretreatment VL.