Red blood cell exchange in children with sickle cell disease.

The aim of our study was to assess the efficacy of red blood cell exchange (RBCx) using a Spectra Optia® automated apheresis system in children with sickle cell disease (SCD). We used automated RBCx to treat acute and chronic complications in 75 children with SCD who had a median age of 10 years [7-13]. We analyzed 649 RBCx sessions. Peripheral venous access was limited in a number of the children, and thus a femoral double-lumen central venous catheter was required. We recommend heparin locking with 500 units in each lumen of the catheter. To prevent complications, we ensured that all patients had achieved a post-RCE HbS level of < 30%. For chronic transfusion, with a post-RCE Hb level of approximately 10-11 g/dL, a blood exchange volume of ≥ 32 mL/kg, and an interval between each RBCx procedure of ≤ 30 days, the residual HbS level was maintained below 30%. For acute transfusion, a post-exchange Hb level ≥ 10 g/dL (p < 0.001) and a total exchange volume ≥ 35 mL/kg (p = 0.001) were the best way to reduce HbS to < 30%. AUC was 0.84. Our results show that erythrocytapheresis was useful and safe for children with SCD.

Bone and joint infections with Staphylococcus aureus strains producing Panton-Valentine Leukocidin in French Guiana.

The aim of this study was to describe the clinical features of bone and joint infections (BJI) due to Panton-Valentine Leukocidin producing (PVL+) Staphylococcus aureus (SA) in French Guiana.A multicenter study that consists of a retrospective charts review of children admitted for PVL+ S. aureus BJI between January 2010 and December 2015.Six patients with SA-PVL BJI were identified during the study period: 2 osteomyelitis, 1 septic arthritis, and 3 disseminated BJI. The median age was 11 years old (4-14 years), and fever lasted for 3.2 days (2-5 days) before diagnosis. An open skin wound preceded the BJI in 5/6 patients. One patient presented with a septic thrombophlebitis of the femoral-popliteal vein on admission. Methicillin-susceptible Staphylococcus aureus (MSSA) were identified for all patients. Three patients had complications: 2 cases of necrotizing pneumonia and 2 pericarditis, with 1 death caused by cardiac tamponade.SA-PVL BJI was not frequent. Strains were susceptible to methicillin, but responsible of severe BJI. Early diagnosis and a multidisciplinary management of these infections are essential to prevent further complications.

Immunosuppression by a subconjunctival implant releasing dexamethasone in a rabbit model of penetrating keratoplasty.

AIMS: To evaluate the efficacy of a subconjunctival dexamethasone-releasing implant in preventing rejection of penetrating keratoplasty (PK) in an animal model. METHODS: Twenty-two rabbits underwent allogenic PK. After randomisation, they received either a 700 µg dexamethasone implant under the conjunctiva at the end of surgery (n=10), one dexamethasone 1 mg/mL eye-drop thrice daily (n=6) or a placebo thrice daily (n=6). The suture was left in place. Animals were observed weekly by slit-lamp and optical coherence tomography with quantification of transparency, neovascularisation and central corneal thickness (CCT). At 5-6 weeks, they were euthanised for histology. The residual dexamethasone concentration in ocular tissues was measured with an ultra-performance liquid chromatography-tandem mass spectrometer. RESULTS: Placebo group: early neovascularisation was systematic, penetrating the graft by 270-360° at 5-6 weeks. Rejection occurred in 50% of cases. Eye-drop and implant groups: similar course without rejection at 6 weeks and normal CCT. Neovascularisation was observed in 5/6 rabbits in the eye-drop group and in 6/8 in the implant group, with two cases of new vessels penetrating the graft from week 3. Neovascularisation scores did not differ significantly between the two treatments and were significantly lower than for the placebo. Histology was in agreement in all cases. Implants disappeared after 3-5 weeks. No local side effect was observed. Tissue concentrations were all higher at day 8 (n=2) in the implant group than in the eye drop group and lower at 6 weeks (n=8). CONCLUSIONS: In this PK model characterised by a high rejection rate, a subconjunctival dexamethasone implant was for 6 weeks as effective as the topical form in preventing allograft rejection.

In Vitro Comparison of the Role of P-Glycoprotein and Breast Cancer Resistance Protein on Direct Oral Anticoagulants Disposition.

BACKGROUND: Pharmacokinetics of direct oral anticoagulants (DOACs) are influenced by ATP-binding cassette (ABC) transporters such as P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP). OBJECTIVES: To better understand the role of transporters in DOAC disposition, we evaluated and compared the permeabilities and transport properties of these drugs. METHODS: Bidirectional permeabilities of DOACs were investigated across Caco-2 cells monolayer. Transport assays were performed using different concentrations of DOAC and specific inhibitors of ABC transporters. Cell model functionality was evaluated by transport assay of two positive control substrates. RESULTS: The results of transport assays suggest a concentration-dependent efflux of apixaban, dabigatran etexilate and edoxaban, whereas the efflux transport of rivaroxaban did not seem to depend on concentration. Verapamil, a strong inhibitor of P-gp, decreased DOAC efflux in the Caco-2 cell model by 12-87%, depending on the drug tested. Ko143 reduced BCRP-mediated DOAC efflux in Caco-2 cells by 46-76%. CONCLUSION: This study allowed identification of three different profiles of ABC carrier-mediated transport: predominantly P-gp-dependent transport (dabigatran), preferential BCRP-dependent transport (apixaban) and approximately equivalent P-gp and BCRP-mediated transport (edoxaban and rivaroxaban).

Asymptomatic multinodular splenoma (splenic hamartoma) in a child with sickle cell anemia.

Splenoma is a rare and benign malformation usually fortuitously diagnosed during imaging, surgery or, unfortunately, at autopsy. Although splenoma was first described in 1861, its association with hematological pathology is a very unusual condition in children. We report the case of an asymptomatic splenoma in an 8-year-old boy with sickle cell anemia, whose diagnosis was confirmed after conventional splenectomy.

Nicotine delivery from the refill liquid to the aerosol via high-power e-cigarette device.

To offer an enhanced and well-controlled nicotine delivery from the refill liquid to the aerosol is a key point to adequately satisfy nicotine cravings using electronic nicotine delivery systems (ENDS). A recent high-power ENDS, exhibiting higher aerosol nicotine delivery than older technologies, was used. The particle size distribution was measured using a cascade impactor. The effects of the refill liquid composition on the nicotine content of each size-fraction in the submicron range were investigated. Nicotine was quantified by liquid chromatography coupled with tandem mass spectrometry. Particle size distribution of the airborne refill liquid and the aerosol nicotine demonstrated that the nicotine is equally distributed in droplets regardless of their size. Results also proved that the nicotine concentration in aerosol was significantly lower compared to un-puffed refill liquid. A part of the nicotine may be left in the ENDS upon depletion, and consequently a portion of the nicotine may not be transferred to the user. Thus, new generation high-power ENDS associated with propylene glycol/vegetable glycerin (PG/VG) based solvent were very efficient to generate carrier-droplets containing nicotine molecules with a constant concentration. Findings highlighted that a portion of the nicotine in the refill liquid may not be transferred to the user.

Paediatric Bone and Joint Infections in French Guiana: A 6 Year Retrospective Review.

The epidemiology of paediatric bone and joint infections from South America is poorly known. We herein report a retrospective study conducted in whole French Guiana from January 2010 to December 2015. Medical charts of 55 previously healthy children were analysed, identifying 27 with osteomyelitis, 22 with septic arthritis and 6 with multifocal infections and/or osteoarthritis. The male:female ratio was 2.2:1, and the mean age was 7.5 years. Eighty percent children were ≥36 months old who had predominantly osteomyelitis related to methicillin-susceptible Staphylococcus aureus (p < 0.05) in the course of neglected skin infections. Five children presented with multi-systemic infections resulting in one fatality, mainly caused by S. aureus producing Panton-Valentine leucocidin (p < 0.01). In contrast, children aged 6-36 months had more likely culture-negative infections (p < 0.05), septic arthritis and mild clinical and biological features. Further prospective studies are required to better guide rational diagnostic and therapeutic strategies.

Assessment of new-generation high-power electronic nicotine delivery system as thermal aerosol generation device for inhaled bronchodilators.

PURPOSE: A need remains for alternative devices for aerosol drug delivery that are low cost, convenient and easy to use for the patient, but also capable of producing small-sized aerosol particles. This study investigated the potential of recent high power electronic nicotine delivery systems (ENDS) as aerosol generation devices for inhaled bronchodilators. METHODS: The particle size distribution was measured using a cascade impactor. The delivery of terbutaline sulfate, a current bronchodilator used for asthma or COPD therapy by inhalation, was studied. This drug was quantified by liquid chromatography coupled with tandem mass spectrometry. RESULTS: The particle size distribution in terms of mass frequency (in two ways, gravimetrically and quantitatively through drug assay on each stage) and the terbutaline sulfate concentration in the aerosol were elucidated. The mass median aerodynamic diameter (MMAD) and the drug delivery rose when the power level increased, to reach 5.6±0.4µg/puff with a MMAD of 0.78±0.03µm at 25W. CONCLUSION: New generation high-power ENDS are very efficient to generate carrier-droplets in the submicron range containing drug molecules with a constant drug concentration whatever the size-fractions. ENDS appear to be highly patient-adaptive.

Direct oral anticoagulants: Current indications and unmet needs in the treatment of venous thromboembolism.

The treatment of acute venous thromboembolism (VTE) is being completely modified with the development of direct oral anticoagulants (DOACs). Rivaroxaban, apixaban and edoxaban directly inhibit factor Xa, whereas dabigatran inhibits factor IIa. All these drugs are proposed orally, and share pharmacological similarities: fixed doses without any therapeutic drug monitoring, key role of the transporter proteins P-glycoprotein for all of them and metabolism mediated by CYP3A4 for the anti-Xa, short half-life with variable rate of renal elimination. More than 25 000 patients with acute VTE were included in phase-III studies. Rivaroxaban and apixaban challenged all the conventional therapy (parenteral heparins followed by anti-vitamin K antagonists) whereas edoxaban and dabigatran challenged only anti-vitamin K antagonists. All the DOACs met the non-inferiority efficacy endpoint (recurrent VTE during treatment), whereas the large non-inferiority margin was debated for dabigatran. However, they were associated with better safety and a decreased risk of major bleeding. According to indirect comparisons, there were no statistically significant differences between DOACs in terms of efficacy but some differences are not excluded in term of safety. Although DOACs allow for simplification of treatment in the majority of patients with acute VTE, their risk/benefit ratio is questioned in elderly patients, patients with mild-to-severe renal impairment, and in some clinical subgroups such as cancer or chronic thromboembolic pulmonary hypertension. Validated reversal strategies (potentially based on laboratory monitoring) are expected for patients with major bleeding, overdose or with a need for surgery.

Effect of Activated Charcoal on Rivaroxaban Complex Absorption.

OBJECTIVE: To quantify the impact of activated charcoal (AC) on rivaroxaban exposure in healthy volunteers. METHODS: This was an open-label study with an incomplete cross-over design of single-dose rivaroxaban (40 mg) administered alone or with AC in 12 healthy volunteers. The study comprised three treatment periods in randomised sequence, one with rivaroxaban administered alone and two with AC given at 2, 5 or 8 h post-dose. Rivaroxaban plasma concentration was measured in blood samples drawn at 16 time points. The pharmacokinetic model of rivaroxaban alone or with AC administration was built using a non-linear mixed-effect modelling approach. RESULTS: The pharmacokinetic model was based on a one-compartment model with an absorption rate described by the sum of three inverse Gaussian densities to reproduce multiphasic and prolonged absorption. The inclusion in the model of each AC administration schedule significantly improved objective function value. AC reduced the area under the rivaroxaban concentration-time curve by 43% when administered 2 h post-dose, by 31% when administered 5 h post-dose and by 29% when administered 8 h post-dose. Based on the estimated pharmacokinetic model, simulations suggested that AC might have an impact even after 8 h post-dose. CONCLUSION: AC administration significantly reduces exposure to rivaroxaban even if AC is administered 8 h after rivaroxaban. These results suggest that AC could be used in rivaroxaban overdose and accidental ingestion to antagonise absorption. CLINICALTRIAL. GOV REGISTRATION NO: NCT02657512.

In vitro and in vivo evaluation of drug-drug interaction between dabigatran and proton pump inhibitors.

To quantify the drug-drug interactions between dabigatran etexilate (DE) and proton pump inhibitors (PPI) and in particular the role of P-gp activity modulation. In the first part of the study, efflux ratios of DE were evaluated using the caco-2 cell line in the presence of pantoprazole, omeprazole, rabeprazole, lansoprazole and ciclosporin A (positive control). The two PPI that reduced the efflux ratio of dabigatran to the greatest and least extent, respectively, were used during the second part of the study, comprising a single-centre, randomised, open-label study with an incomplete Latin square design. Nine healthy volunteers received DE (150 mg) alone, DE (150 mg) with the first PPI and DE (150 mg) with the second PPI in randomised sequence. Dabigatran plasma concentration and thrombin time were measured in blood samples withdrawn at 11 time points after each treatment. Models were built using a nonlinear mixed-effect modelling approach. Omeprazole and rabeprazole were the two PPI that reduced the efflux ratio of DE least and most, respectively. The PK model was based on an inverse Gaussian absorption process with one compartment. The relationship between dabigatran concentration and thrombin time was considered linear. Some PK profiles had dramatically low concentration values due to poor absorption. These profiles were clustered using a between subject model mixture with interoccasion variability. The concomitant administration of PPI did not significantly change dabigatran pharmacokinetics. DE is subject to high absorption variability, precluding evaluation of the effect of PPI on its pharmacokinetics.

Associated factors of acute chest syndrome in children with sickle cell disease in French Guiana.

A matched case-control study was performed in order to identify some associated factors for ACS or to confirm the published data. Controls were children hospitalized during the same period for pain crisis who did not develop an ACS during hospitalization. Between January 2006 and October 2010, there were 24 episodes of ACS distributed among 19 patients (8 girls and 11 boys). The median age was 7.5 years (range: 3 to 17 years) for the cases and 7 years (range: 3-18 years) for the controls. Four cases and 11 controls were treated with hydroxyurea (HU). In 75% of the cases, the ACS had arisen 24-72 hours following admission. The independent factors associated with ACS were average Hb rate <8 g/dL (OR = 4.96, 95% CI = 1.29-27.34, and P = 0.04), annual number of hospitalizations >3 (OR = 5.44, 95% CI = 3.59-8.21, and P = 0.003), average length of hospitalization >7 days (OR = 3.69, 95% CI = 3.59-8.21, and P = 0.003), and a pathological transthoracic echocardiography (TTE) (OR = 13.77, 95% CI = 2.07-91.46, and P = 0.003). Although the retrospective design and small sample size are weaknesses of the present study, these results are consistent with those of previous studies and allowed identifying associated factors such as a pathological TTE.

Quantification of total and unbound tranexamic acid in human plasma by ultrafiltration liquid chromatography/tandem mass spectrometry: application to pharmacokinetic analysis.

The present work describes the development and validation of rapid, sensitive and accurate liquid chromatography method, coupled with tandem mass spectrometry detection, for quantification of tranexamic acid in human plasma using isotopically labeled internal standard (IS). A one-step plasma protein precipitation was performed with acetonitrile. UPLC BEH amide column was used for chromatographic separation. Tranexamic acid and IS were detected in multiple reaction monitoring in electrospray positive ionization. The method was linear over the concentration range of 0.8-200mg/L. The intra- and inter-day precision values were below 11.5% and accuracy was better than 9.6%. Total analysis time was reduced to 6min including sample preparation. The present method was successfully applied to pharmacokinetic pilot study in patients undergoing orthopedic surgery. Ultrafiltration allowed confirming the weak binding to plasma proteins and confirming that total plasma TXA concentration is measured by this assay.

Rapid determination of apixaban concentration in human plasma by liquid chromatography/tandem mass spectrometry: application to pharmacokinetic study.

We described the development and full validation of a rapid, high throughput sensible and accurate LC method using tandem mass spectrometry detection for determining apixaban concentration with [(¹³C, ²H7]-apixaban as internal standard in human plasma. Plasma pretreatment involved a one-step protein precipitation with methanol. The separation was performed by reverse-phase chromatography on a Luna MercuryMS C18 column (20 mm × 4 mm × 3 µm) column. The multiple reaction monitoring transitions used for quantification were m/z 460.20→443.27 and 460.20→198.99 for apixaban, 468.22→451.30 for [(¹³C, ²H7]-apixaban in the electrospray positive ionization mode. The method was linear over the concentration range of 5-500 µg/L. The intra- and inter-day precision values were below 14% and accuracy was from 90.0 to 105.8% at all quality control levels. Sample analysis time was less than 10 min including sample preparation. The present method was successfully applied to a pharmacokinetic study following oral administration of apixaban.

Performance of creatinine and cystatin C-based glomerular filtration rate estimating equations in a European HIV-positive cohort.

OBJECTIVE: To validate glomerular filtration rate (GFR) estimating equations in white HIV-infected patients based on serum creatinine and/or serum cystatin C. DESIGN: Single-center, cross-sectional evaluation of the predictive performance of GFR estimators. METHODS: GFR was measured by iohexol plasma clearance. Serum creatinine (Scr) and serum cystatin C (Scyst) were measured by traceable and standardized methods. We evaluated the performance of the Modification of Diet in Renal Disease (MDRD) and the Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equations. We also studied the performance of the cystatin C-based equation (CKD-EPI Scyst) and the combined cystatin and creatinine-based equation (CKD-EPI combined), as recently proposed by the CKD-EPI group. RESULTS: Two hundred and three participants (18% of women) were included. Mean age was 49 ± 10 years. Mean measured GFR (mGFR) was 95 ± 24 ml/min per 1.73 m². CKD-EPI and CKD-EPI combined significantly outperformed the MDRD equation. The percentage of estimating results within 30% of mGFR was 75, 82 and 81% for the MDRD, CKD-EPI and CKD-EPI combined equation, respectively. Results favoring the CKD-EPI and CKD-EPI combined equation were especially observed for patients with mGFR over 90 ml/min per 1.73 m². CONCLUSION: In our European HIV cohort, we confirmed that the creatinine-based CKD-EPI equation should replace the MDRD study equation. However, global performance of this equation remains worse than the performance observed in the general population. This lesser performance is particularly relevant in patients with measured GFR under and around 60 ml/min per 1.73 m². Moreover, the specific interest of Scyst-based equations is not confirmed in this population.

Investigation of drug-drug interactions between clopidogrel and fluoxetine.

Drug-drug interactions may contribute to the variability of the response of clopidogrel. Several hypotheses have been proposed concerning the potential modification of clopidogrel pharmacokinetics and pharmacodynamics by fluoxetine. This open-label crossover study assessed the effect of fluoxetine on the pharmacological activity of clopidogrel in healthy volunteers. Eight healthy male volunteers received a single 600-mg loading dose of clopidogrel followed by 20 mg of fluoxetine on 4 days and then 20 mg of fluoxetine plus 600 mg of clopidogrel on the fifth day. Eleven blood samples were withdrawn after clopidogrel administration to determine plasma concentrations of clopidogrel active metabolite (CAM) and platelet function. Platelet aggregation was measured by light transmittance aggregometry (LTA) and platelet reactivity index by flow cytometric vasodilator-stimulated phosphoprotein (VASP) analysis. The areas under the curve and maximum plasma concentrations of CAM were, respectively, 20.6 and 25.3% lower after co-administration of fluoxetine compared with administration of clopidogrel alone. The percentage maximum platelet aggregation values in the presence of 5 µM and 10 µM adenosine diphosphate, measured by LTA, were, respectively, 13.9 and 22.4% lower after fluoxetine co-administration. The platelet reactivity index measured by the flow cytometric VASP method was 36.8% lower when clopidogrel was administered in conjunction with fluoxetine.

A semi-mechanistic absorption model to evaluate drug-drug interaction with dabigatran: application with clarithromycin.

AIM: The aim of this study was to develop a PK/PD model to assess drug-drug interactions between dabigatran and P-gp modulators, using the example of clarithromycin, a strong inhibitor of P-gp. METHODS: Ten healthy male volunteers were randomized to receive in the first treatment period a single 300 mg dose of dabigatran etexilate (DE) and in the second treatment period 500 mg clarithromycin twice daily during 3 days and then 300 mg DE plus 500 mg clarithromycin on the fourth day, or the same treatments in the reverse sequence. Dabigatran plasma concentration and ecarin clotting time (ECT) were measured on 11 blood samples. Models were built using a non-linear mixed effect modelling approach. RESULTS: The best PK model was based on an inverse Gaussian absorption process with two compartments. The relationship between dabigatran concentration and ECT was implemented as a linear function. No continuous covariate was associated with a significant decrease in the objective function. The concomitant administration of clarithromycin induced a significant change only in DE bioavailability, which increased from 6.5% to 10.1% in the presence of clarithromycin. Clarithromycin increased peak concentration and AUC by 60.2% and 49.1% respectively. CONCLUSION: The model proposed effectively describes the complex PK of dabigatran and takes into account drug-drug interactions with P-gp activity modulators, such as clarithromycin.

[Severe meprobamate poisoning: description of 146 cases in a French department]. / Intoxications graves au méprobamate : description d'une série de 146 cas dans le département de la Loire.

Meprobamate poisoning are serious and sometimes fatal. Faced with a potential stop of marketing, we conducted a multicenter retrospective study to assess the severity criteria presented by patients admitted to the ICU for severe meprobamate poisoning, whether with alone form or in combination with aceprometazine. One hundred fourty-six patients have been enrolled between January 2005 and June 2011: 38 had a single meprobamate poisoning, 104 to meprobamate and aceprometazine and 4 to both forms. At admission, 88% of patients exhibited coma (Glasgow ≤ 7) and half of them a systolic blood pressure ≤ 90 mmHg. Mortality rate was 3%. Our results did not find any significant between-group difference, either in regard of clinical or biological severity criteria. These data argue for a cessation of marketing of all meprobamate-based specialities.

Mycophenolate sodium dosing in combination with tacrolimus: pharmacokinetic evaluation of a novel regimen in de novo tacrolimus-treated kidney transplant patients.

BACKGROUND: There are no clear guidelines concerning the appropriate dose of mycophenolate acid (MPA) to be used in association with tacrolimus. When MPA is given at an approved fixed dose in cyclosporine-treated patients, initial systemic under exposure is frequent and associated with the occurrence of acute rejection. We pharmacologically evaluated in tacrolimus-treated recipients a novel dosing regimen of MPA with an initial high dose followed by a gradual decrease over time. METHODS: 15 de novo tacrolimus-treated kidney transplant patients were administered mycophenolate sodium at the dose of 720 mg b.i.d. for the first week post-transplant, 540 mg b.i.d. until Day 30, and then 360 mg b.i.d. until Day 90. MPA exposure was evaluated by the 12 h area under MPA concentration versus time curve (AUC) determined at Days 2, 7, 15, 30 and 90 post-transplant. RESULTS: Median MPA AUC was constantly within the therapeutic window of 30 - 60 mg/l × h throughout the three months of evaluation. More than 75% of patients had a MPA AUC above 30 mg/l × h at Day 2 and Day 7 post-transplant. CONCLUSION: This exploratory study suggests that such a dosing regimen of mycophenolate sodium might quickly offer and sustain an optimal exposure to MPA in tacrolimus-treated kidney transplant patients.

UPLC MS/MS assay for routine quantification of dabigatran - a direct thrombin inhibitor - in human plasma.

This article described the development and full validation of rapid and accurate liquid chromatography method, coupled with tandem mass spectrometry detection, for quantification of dabigatran in human plasma with [(13)C(6)]-dabigatran as internal standard. Plasma pretreatment involved a single step protein precipitation with methanol. Separation was performed by ultra performance reversed-phase chromatography on an Acquity UPLC BEH C8 100 mm × 1 mm × 1.7 µm column using a gradient elution mode. The mobile phase was a mix of distilled water containing 0.1% formic acid and methanol containing 0.1% formic acid. Specific multiple reaction monitoring transitions were recorded in positive electrospray ionization. The method was linear over the concentration range of 2-500 µg/L. The intra- and inter-day precision values were below 11.3% and accuracy was within 93.8% and 108.8% for all QC levels (5, 75 and 400 µg/L). The lower limit of quantification was 2 µg/L. Total analysis time was to 10 min including sample preparation.