Suboptimal exposure to fluconazole in critically ill patients: Pharmacokinetic analysis and determinants.

OBJECTIVES: This study aims at evaluating fluconazole exposure in critically ill patients and identifying variables associated with the latter. PATIENTS AND METHODS: This was a 2-year (2018-2019) retrospective multicenter cohort study. Adult patients > 18 years-old with at least one fluconazole concentration measurement during their ICU stay were included. RESULTS: Twenty patients were included. Only 11 patients had a fluconazole trough concentration (Cmin) within the target range (≥15 mg/L). According to bivariable analysis, SOFA score, GGT, fluconazole clearance, Ke, and Vd, were independently associated with a decrease in fluconazole Cmin. The median loading dose required to achieve the Cmin target appeared to be greater in patients with higher SOFA or GGT level and in patients undergoing renal replacement therapy. CONCLUSIONS: This study supports recommendation for routine fluconazole therapeutic drug monitoring in ICU patients so as to avoid underexposure, especially if SOFA score is ≥ 7 and/or GGT is ≥ 100 U/L.

Drug-related problems among older patients: Analysis of 8 years of pharmacist's interventions.

OBJECTIVES: To analyse the most frequent DRP over time and pharmacists' interventions made among older patients aged over 75 years old. DRP between older patients and younger patients aged 18 to 74 years and between older patients treated in geriatric wards or not were also compared. METHODS: A cross-sectional observational study conducted on DRP detected by pharmacists at the university hospital centre of Lyon and prospectively recorded in the Act-IP© database from January 2008 to December 2015. RESULTS: A total of 56,223 DRP were investigated - 19,056 in older patients and 37,167 in younger patients. A supratherapeutic dosage was mainly reported (22.4% in older patients vs. 19.0% in younger patient) and pharmacists made interventions mostly to adjust dosage (27.3% vs. 24.2%). Physicians' acceptance was significantly lower in older patients (57.1% vs. 64.3%). DRP associated to a drug included a supratherapeutic use of acetaminophen (5.2% vs. 3.8%) and hypnotics (4.0% vs. 1.4%), medication in cardiology used without indication (1.4% vs. 0.2%) and underuse of vitamin D (1.2% vs. 0.1%). Supratherapeutic dosages were more significantly detected with a lower overall physicians' acceptance in older patients treated in general wards. CONCLUSIONS: This study highlights the specificity of DRP among older patients and encourages health care professionals to remain especially alert regarding older patients treated in general wards. These findings can contribute to define or adjust training needs and quality indicators to improve the daily practices of health care professionals.

Tolerance and microbiological efficacy of cefepime or piperacillin/tazobactam in combination with vancomycin as empirical antimicrobial therapy of prosthetic joint infection: a propensity-matched cohort study.

BACKGROUND: The use of piperacillin/tazobactam with vancomycin as empirical antimicrobial therapy (EAT) for prosthetic joint infection (PJI) has been associated with an increased risk of acute kidney injury (AKI), leading us to propose cefepime as an alternative since 2017 in our reference centre. OBJECTIVES: To compare microbiological efficacy and tolerance of these two EAT strategies. METHODS: All adult patients with PJI empirically treated with vancomycin+cefepime (n = 89) were enrolled in a prospective observational study and matched with vancomycin+piperacillin/tazobactam-treated historical controls (n = 89) according to a propensity score including age, baseline renal function and concomitant use of other nephrotoxic agents. The two groups were compared using Kaplan-Meier curve analysis, and non-parametric tests regarding the proportion of efficacious empirical regimen and the incidence of empirical therapy-related adverse events (AE). RESULTS: Among 146 (82.0%) documented infections, the EAT was considered efficacious in 77 (98.7%) and 65 (98.5%) of the piperacillin/tazobactam- and cefepime-treated patients, respectively (P = 1.000). The rate of AE, particularly AKI, was significantly higher in the vancomycin+piperacillin/tazobactam group [n = 27 (30.3%) for all AE and 23 (25.8%) for AKI] compared with the vancomycin+cefepime [n = 13 (14.6%) and 6 (6.7%)] group (P = 0.019 and <0.001, respectively), leading to premature EAT discontinuation in 20 (22.5%) and 5 (5.6%) patients (P = 0.002). The two groups were not significantly different regarding their comorbidities, and AKI incidence was not related to vancomycin plasma overexposure. CONCLUSIONS: Based on the susceptibility profile of bacterial isolates from included patients, microbiological efficacy of both strategies was expected to be similar, but vancomycin + cefepime was associated with a significantly lower incidence of AKI.

[Peripheral neuropathy with hypervitaminosis B6 caused by self-medication]. / Neuropathie périphérique avec hypervitaminose B6 provoquée par l'automédication.

INTRODUCTION: Vitamin B6 is contained in a number of over-the-counter drugs and vitamin supplements. It may cause severe neurological troubles in case of overdosage. CASE REPORT: We report the case of a 92-year-old women with gait disorders. A diagnosis of peripheral neuropathy with both motor and sensitive deficits was established and investigated. Blood level of vitamin B6 was measured to investigate a potential deficiency. Unexpectedly, the results showed hypervitaminosis B6, which appears to be due to self-administration of an over-the-counter drug containing vitamin B6. Discontinuation of this drug was associated with decrease in vitamin B6 level as well as gait improvement. We also discuss the toxicity of vitamin B6. CONCLUSION: Hypervitaminosis B6 remains a possible cause of peripheral neuropathy and it may be caused by self-administration of over-the-counter vitamin-containing drugs.

A Generic Model for Quantitative Prediction of Interactions Mediated by Efflux Transporters and Cytochromes: Application to P-Glycoprotein and Cytochrome 3A4.

BACKGROUND AND OBJECTIVE: The In Vivo Mechanistic Static Model (IMSM) is a powerful method used to predict the magnitude of drug-drug interactions (DDIs) mediated by cytochromes. The objective of this study was to extend the IMSM paradigm to DDIs mediated by efflux transporters and cytochromes. METHODS: First, a generic model for this kind of interaction was devised. A flexible approach was then developed to estimate the characteristic parameters [the contribution ratios (CRs) and inhibition or induction potencies (IXs)] from clinical data by non-linear regression. Next, this approach was applied to the DDIs mediated by P-glycoprotein (P-gp) and cytochrome P450 (CYP) 3A4/3A5 in a large set of victim drugs and interactors. Lastly, the model and associated parameters were used to identify the DDIs most at risk of overexposure. RESULTS: A total of 25 substrates and 26 interactors (three inducers, 23 inhibitors) could be considered in the regression analysis. The number of observations [area under the plasma concentration-time curve ratios or renal clearance ratios (Robs)] was 138. Fifty CRs and 57 IXs were estimated. The proportions of predictions within 0.67- to 1.5-fold Robs and within 0.5- to 2-fold Robs were 79% and 93% for the internal validation and 76% and 88% for the external validation, respectively. The median fold error was 0.98 (the ideal value is 1) and the interquartile range of the fold error was 0.36. The relative standard error of parameter estimates was a maximum of 15%. CONCLUSIONS: The IMSM approach was successfully extended to DDIs mediated by P-gp and CYP3A4/3A5. The method revealed good predictive performances by internal and external validation.

A practical approach to tuberculosis diagnosis and treatment in liver transplant recipients in a low-prevalence area.

Solid organ transplant candidates/recipients are at risk of mycobacterial infections. Although guidelines on the management of latent tuberculosis infection and active tuberculosis are available for solid organ transplant recipients, limited guidance focuses on end-stage liver disease or liver transplant recipients who require management in a referral center. Therapeutic challenges arise from direct antituberculosis drug-related hepatotoxicity, and substantial metabolic interactions between immunosuppressive and antituberculosis drugs. Another issue is the optimal timing of therapy with regards to the time of transplantation. This review focuses on the importance of tuberculosis screening with immunological tests, challenges in the diagnosis, management, and treatment of latent tuberculosis infection and active tuberculosis, as well as risk assessment for active tuberculosis in the critical peri-liver transplantation period. We detail therapeutic adjustments required for the management of antituberculosis drugs in latent tuberculosis infection and active tuberculosis, particularly when concomitantly using rifampicin and immunosuppressive drugs.

[Pharmacokinetic risk factors of beta-blockers overdose in the elderly: Case report and pharmacology approach]. / Facteurs de risque pharmacocinétiques de surdosage en bêta-bloquants chez les patients âgés : cas clinique et rationnel pharmacologique.

Beta-blockers are widely prescribed in elderly patients and may induce severe adverse drug reactions. We report a case of bisoprolol-induced bradycardia in an elderly patient with impaired renal function and use of cytochrome P450 inhibitors. A literature review has been performed in order to analyze pharmacokinetic risk factors of beta-blockers overdosing in geriatrics. Various mechanisms can result in decreased elimination of beta-blockers. These mechanisms vary according to the beta-blocker agent and may be combined in some individuals, especially elderly patients. This can lead to unexpected overexposure. Knowledge about drug interactions and pharmacokinetic elimination pathways is important for preventing overexposure and adverse drug reactions when using beta-blockers.

Factors associated with changes in exposure to anticholinergic and sedative medications in elderly hospitalized patients: multicentre longitudinal study.

BACKGROUND AND PURPOSE: Elderly patients exposed to drugs with anticholinergic or sedative properties may have an increased risk of adverse events. This study aimed to assess the relationship between patient characteristics and changes of exposure to anticholinergic and sedative medications during their hospital stay. METHODS: A multicentre longitudinal study was set up on hospitalized patients (aged ≥65 years) using at least one drug at admission. The primary outcome was change of exposure to anticholinergic and sedative drugs between admission and discharge. Sociodemographic characteristics of the patients, comorbidities, life habits and information about the hospital stay (origin of admission, reasons for hospitalization) were collected. RESULTS: The study included 337 patients (mean age, 85.4 years) with an average hospital stay of 30.1 ± 37.5 days. The drug burden index increased during the hospital stay among males (P = 0.03), patients for whom the reason for hospitalization was either a stroke (P = 0.001) or inability to stay in their own home (P = 0.001), and patients with diabetes mellitus (P = 0.009). In the adjusted model, drug burden index increased among patients hospitalized for stroke, inability to stay in their own home or post-surgery, and for patients with diabetes mellitus or hypertension. CONCLUSIONS: The drug management of elderly patients during hospital stays may increase exposure to anticholinergic and sedative drugs. Although the anticholinergic and sedative properties may be in relation to the therapeutic purpose, they also represent an unexpected risk. Physicians and clinical pharmacists should consider performing optimization of the drug prescriptions for patients at risk.

A Model for Predicting the Interindividual Variability of Drug-Drug Interactions.

Pharmacokinetic drug-drug interactions are frequently characterized and quantified by an AUC ratio (Rauc). The typical value of the AUC ratio in case of cytochrome-mediated interactions may be predicted by several approaches, based on in vitro or in vivo data. Prediction of the interindividual variability of Rauc would help to anticipate more completely the consequences of a drug-drug interaction. We propose and evaluate a simple approach for predicting the standard deviation (sd) of Ln(Rauc), a metric close to the interindividual coefficient of variation of Rauc. First, a model was derived to link sd(Ln Rauc) with the substrate fraction metabolized by each cytochrome and the potency of the interactors, in case of induction or inhibition. Second, the parameters involved in these equations were estimated by a Bayesian hierarchical model, using the data from 56 interaction studies retrieved from the literature. Third, the model was evaluated by several metrics based on the fold prediction error (PE) of sd(Ln Rauc). The median PE was 0.998 (the ideal value is 1) and the interquartile range was 0.96-1.03. The PE was in the acceptable interval (0.5 to 2) in 52 cases out of 56. Fourth, a surface plot of sd(Ln Rauc) as a function of the characteristics of the substrate and the interactor has been built. The minimal value of sd(Ln Rauc) was about 0.08 (obtained for Rauc = 1) while the maximal value, 0.7, was obtained for interactions involving highly metabolized substrates with strong interactors.

Improved outcome of children transplanted for high-risk leukemia by using a new strategy of cyclosporine-based GVHD prophylaxis.

There is currently a major concern regarding the optimal immunosuppression therapy to be administered after hematopoietic stem cell transplantation (HSCT) to reduce both the toxicity of GvHD and the rate of relapse. We report the outcome of high-risk leukemia children transplanted with a new way of managing cyclosporine (CsA)-based GvHD prophylaxis. A total of 110 HSCT in 109 ALL or AML children who received CsA without mycophenolate or methotrexate in matched related as well as in matched or mismatched unrelated stem cell transplantation were included. CsA dosage regimens were individualized to obtain specific trough blood concentrations values. The incidences of grade I-II and III-IV acute GvHD were 69.1% and 1.8%, respectively, and 8.4% for chronic GvHD. GvHD was neither more frequent nor severe in unrelated than in related HSCT. GvHD occurred in 87% of patients with a mean CsA trough concentration ⩽120 ng/mL versus 43% with concentration >120 ng/mL (P<0.0001). Five-year disease-free survival (DFS) and overall survival were 78% and 83.6%, respectively. DFS was 76.9% for ALL and 80.4% for AML patients. There was no difference in DFS between matched siblings and matched unrelated or mismatched unrelated HSCT. DFS in patients with minimal residual disease (MRD) ⩾10(-3) and in those with MRD <10(-3) before SCT was comparable. Our results indicate that a GvHD prophylaxis regimen based on CsA without mycophenolate or methotrexate is safe and effective whatever the donor compatibility is. These results suggest that GvL effect may be enhanced by this strategy of GvHD prophylaxis.

Should busulfan therapeutic range be narrowed in pediatrics? Experience from a large cohort of hematopoietic stem cell transplant children.

Busulfan, the corner stone of hematopoietic stem cell transplantation regimens, has a narrow therapeutic window. Therapeutic drug monitoring (TDM)-guided dosing to reach the conventional area under the concentration-time curve (AUC) target range of 900-1500 µmol min/L is associated with better outcomes. We report our experience with busulfan TDM in a large cohort of children. The aims were to investigate the relevance of using a more restricted therapeutic range and investigate the association between busulfan therapeutic range and clinical outcome. This study includes 138 children receiving 16 doses of intravenous busulfan, with the first dose assigned based on weight and doses adjusted to a local AUC target range of 980-1250 µmol min/L. Busulfan TDM combined with model-based dose adjustment was associated with an increased probability of AUC target attainment, for both target range: 90.8% versus 74.8% for the conventional target range and 66.2% versus 43.9% for the local target range (P<0.001). The median follow-up was 56.2 months. Event-free survival was 88.5%, overall survival was 91.5% and veno-occlusive disease occurred in 18.3% of patients. No difference was observed for clinical outcomes depending on the selected target range. Pharmacokinetic monitoring and individualization of busulfan dosage regimen are useful in improving target attainment, but using a restricted target range has no impact on clinical outcomes.

Population modeling and simulation study of the pharmacokinetics and antituberculosis pharmacodynamics of isoniazid in lungs.

Among first-line antituberculosis drugs, isoniazid (INH) displays the greatest early bactericidal activity (EBA) and is key to reducing contagiousness in treated patients. The pulmonary pharmacokinetics and pharmacodynamics of INH have not been fully characterized with modeling and simulation approaches. INH concentrations measured in plasma, epithelial lining fluid, and alveolar cells for 89 patients, including fast acetylators (FAs) and slow acetylators (SAs), were modeled by use of population pharmacokinetic modeling. Then the model was used to simulate the EBA of INH in lungs and to investigate the influences of INH dose, acetylator status, and M. tuberculosis MIC on this effect. A three-compartment model adequately described INH concentrations in plasma and lungs. With an MIC of 0.0625 mg/liter, simulations showed that the mean bactericidal effect of a standard 300-mg daily dose of INH was only 11% lower for FA subjects than for SA subjects and that dose increases had little influence on the effects in either FA or SA subjects. With an MIC value of 1 mg/liter, the mean bactericidal effect associated with a 300-mg daily dose of INH in SA subjects was 41% greater than that in FA subjects. With the same MIC, increasing the daily INH dose from 300 mg to 450 mg resulted in a 22% increase in FA subjects. These results suggest that patients infected with M. tuberculosis with low-level resistance, especially FA patients, may benefit from higher INH doses, while dose adjustment for acetylator status has no significant impact on the EBA in patients with low-MIC strains.

[Lower limb edema during valpromide treatment: case report and literature review]. / Œdèmes des membres inférieurs au cours d'un traitement par valpromide : cas clinique et revue de la littérature.

INTRODUCTION: Valpromide and sodium divalproate are indicated in the treatment of maniac episodes of bipolar disorder. These drugs are metabolized into valproic acid. The occurrence of peripheral edema has been described as a very rare adverse reaction of those drugs. CASE REPORT: We report the case of a patient treated with valpromide who presented edema of the lower limbs. The increase in furosemide dose allowed regression of edema, and valpromide discontinuation resulted in rapid normalization. Recurrence of mood disorders led to the reintroduction of valpromide, which was associated with recurrence of edema. The definitive withdrawal of valpromide resulted in resolution of edema. CONCLUSION: Edema of the lower limbs can be induced by valproate. The mechanism of this reaction is unknown. These edema appear to be reversible upon discontinuation of the drug. Clinicians should be aware of a possible relationship between valproate-derived drugs and peripheral edema.

Prescriptions analysis by clinical pharmacists in the post-operative period: a 4-year prospective study.

BACKGROUND: Clinical pharmacists can help prevent medication errors. However, data are scarce on their role in preventing medication prescription errors in the post-operative period, a high-risk period, as at least two prescribers can intervene, the surgeon and the anesthetist. We aimed to describe and quantify clinical pharmacist' intervention (PIs) during validation of drug prescriptions on a computerized physician order entry system in a post-surgical and post-transplantation ward. We illustrate these interventions, focusing on one clearly identified recurrent problem. METHODS: In a prospective study lasting 4 years, we recorded drug-related problems (DRPs) detected by pharmacists and whether the physician accepted the PI when prescription modification was suggested. RESULTS: Among 7005 orders, 1975 DRPs were detected. The frequency of PIs remained constant throughout the study period, with 921 PIs (47%) accepted, 383 (19%) refused and 671 (34%) not assessable. The most frequent DRP concerned improper administration mode (26%), drug interactions (21%) and overdosage (20%). These resulted in a change in the method of administration (25%), dose adjustment (24%) and drug discontinuation (23%) with 307 drugs being concerned by at least one PI. Paracetamol was involved in 26% of overdosage PIs. Erythromycin as prokinetic agent, presented a recurrent risk of potentially severe drug-drug interactions especially with other QT interval-prolonging drugs. Following an educational seminar targeting this problem, the rate of acceptation of PI concerning this DRP increased. CONCLUSION: Pharmacists detected many prescription errors that may have clinical implications and could be the basis for educational measures.

Genotype-based quantitative prediction of drug exposure for drugs metabolized by CYP2D6.

We propose a framework to enable quantitative prediction of the impact of CYP2D6 polymorphisms on drug exposure. It relies mostly on in vivo data and uses two characteristic parameters: one for the drug and the other for the genotype. The metric of interest is the ratio of drug area under the curve (AUC) in patients with mutant genotype to the AUC in patients with wild-type genotype. Any combination of alleles, as well as duplications, may be accommodated in the framework. Estimates of the characteristic parameters were obtained by orthogonal regression for 40 drugs and five classes of genotypes, respectively, including poor, intermediate, and ultrarapid metabolizers (PMs, IMs, and UMs). The mean prediction error of AUC ratios was -0.05, and the mean prediction absolute error was 0.20. An external validation was also carried out. The model may be used to predict the variations in exposure induced by all drug-genotype combinations. An application of this model to a rare combination of alleles (*4*10) is described.

[Interindividual pharmacokinetic variability in long-term antibiotherapy]. / Variabilité pharmacocinétique intra-individuelle et traitement antibiotique prolongé.

OBJECTIVE: The authors wanted to assess intraindividual pharmacokinetic variability, with a case of long-term amikacin therapy. DESIGN: A 92-year-old female patient, weighing 44kg, with renal failure, was treated by amikacin for 52 days. Her individual pharmacokinetic parameters were assessed 12 times in the course of therapy. The intraindividual variability of key parameters was quantified and compared with published interindividual variability. RESULTS: Intraindividual volume and clearance variability was measured at about one fourth to one third of the value observed for interindividual variability. Half-life intraindividual variability was almost equivalent to the interindividual variability: 24.5% versus 32%. CONCLUSIONS: The high pharmacokinetic variability observed has important potential clinical consequences. This case illustrates the need to ensure the effectiveness of treatment, to re-evaluate periodically the patient's status in order to take into account the intraindividual variability of pharmacokinetics parameters.