[Pharmacokinetic risk factors of beta-blockers overdose in the elderly: Case report and pharmacology approach]

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.

Risk factors for urinary tract infections in geriatric hospitals

BACKGROUND

Urinary tract infection (UTI) is the most frequent nosocomial infection in geriatric units. An understanding of risk factors for infection may help to identify prevention strategies.

AIM

Identification of the risk factors for UTI in elderly patients.

METHODS

Retrospective analysis of three prospective cohorts. All hospitalized patients present in, or admitted to, a geriatric unit from June 1st to June 28th, for the years 2009, 2012, and 2015 were included and followed until discharge or until June 30th of the year concerned. For each patient, type and dates of stay, type and dates of catheter, risk factors, and nosocomial UTI (NUTI) data were collected. Univariate and multivariate (Cox model) analyses were made using SPSS software.

FINDINGS

A total of 4669 patients were included and were followed for a total of 83,068 days. There were 189 NUTIs (4.0% patients). NUTIs were significantly more frequent among female patients, in rehabilitation units, in immunosuppressed patients, among those with acute retention, post-void residual, history of urinary tract infection in the previous six months, and in case of dependency. NUTIs were significantly more frequent among those who had a catheter (Z-test, P < 0.001). NUTIs were more frequent among patients with intermittent, indwelling, or suprapubic catheters. They were also more frequent in acute/subacute care or rehabilitation units, in women, in immunosuppressed patients, and in those with a history of previous UTI; they were less frequent in dementia patients.

CONCLUSION

The occurrence of NUTI is an important issue in both catheterized and non-catheterized patients; prevention programmes should be widened to include non-catheterized patients.

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.

New developmental data for Cynomya mortuorum (L., 1761) in Belgium (Diptera: Calliphoridae)

The calliphorid Cynomya mortuorum (L., 1761) is a forensically important species mainly found in the Palearctic region. Knowledge about its biology and ecology is scarce. Thermal constants as well as developmental time were studied at constant and variable regimes of 5 average temperatures: 14, 16, 18, 20 and 22°C, respectively. Total developmental time varied between 15.82±0.40 days at 22°C and 28.67±2.38 days at 14°C, for the constant regime, and between 16.05±0.67 days at 22°C and 32.79±1.77 days at 14°C, for the variable regime. No significant differences were observed between ADD, and threshold at the constant (ADD: 277.39±14.78 DD; lower threshold: 4.72°C) and variable regimes (275.99±14.16 DD; lower threshold: 5.05°C).

Study of relationship between volume of distribution and body weight application to amikacin

Amikacin use is difficult because of its narrow therapeutic and its pharmacokinetic variability. This variability of amikacin is not well known. To adapt amikacin the physician assumes that there is a linear and continuous relation between the volume of distribution and the body weight. The objective of our study was to evaluate the relationship between the volume of distribution (Vd) and the body weight (BW) using a non parametric statistical analysis of dependence so called Z method. Retrospective pharmacokinetic population study and statistic analysis. 872 patients receiving intravenous amikacin. The volume of distribution was modelled using the Non Parametric Adaptive Grid algorithm (NPAG) for a two-compartment model with intravenous infusion. Z coefficient was performed to evaluate the relationships between Vd and BW. For the 872 patients (mean age of 73 ± 17 years) dispatched as follow 53 % female and 47 % male, the analysis of the statistical relationships by the non parametric Z analysis showed a scattered linkage between Vd and BW. For the whole population, the relationship between Vd and BW was not linear (regression analysis). Z analysis demonstrated that only for 80 % of patients there is a relationship between Vd and BW. For these patients, regression analysis give a significant adjustment of a linear model (r = 0.47, p < 0.001). In the whole studied population there is not a continuous and linear relationship between Vd estimated by NPAG and the BW. These results underline the difficulties to adapt doses of amikacin with only BW information.

[Inter-individual and intra-individual pharmacokinetic variability during teicoplanin therapy in geriatric patients]

OBJECTIVES

The authors had for aim to assess the inter- and intra-individual variability of teicoplanin pharmacokinetic parameters in geriatric patients.

METHODS

A cohort of 90 geriatric patients, treated with teicoplanin, was used to build two models describing the pharmacokinetics of teicoplanin, at the beginning and at the end of treatment respectively.

RESULTS

The inter- and intra-individual variability of parameters were important as shown respectively by the coefficients of variation of pharmacokinetic parameters ranging from 125 to 694% and the half-life change during the treatment (by a factor of three to more than 30) for 60% of patients.

CONCLUSIONS

The results revealed that elderly patients presented significant variability, which was only partly explained by the renal function. Therapeutic monitoring of teicoplanin in geriatric patients should be undertaken at the end of the loading dose and repeatedly during the maintenance phase to prevent over- or underexposure.

Guidelines for aminoglycoside use and applicability to geriatric patients

OBJECTIVES

The authors had for objective to evaluate the applicability of AFSSAPS guidelines for aminoglycoside use to geriatric patients.

METHODS

Theoretical doses and dosing regimens allowing reaching target concentrations in this population were calculated by applying a pharmacokinetic model to 30 geriatric patients treated by amikacin.

RESULTS

The dose allowing reaching a maximum concentration of 60 mg/L was 1.217 mg on average. The time required to reach a blood concentration lower than or equal to 2.5mg/L was 62.5±70.4 hours. Forty-six percent of patients had a trough concentration greater than 2.5 mg/L, 48 hours after administration. For these patients, the time between critical minimum inhibitory concentration (MIC) and toxicity threshold concentration was 21.9±14.9 hours.

CONCLUSION

Reaching a target concentration can be problematic in geriatric patients. It is frequently necessary to use dosing intervals greater than 48 hours. The effectiveness and safety of these regimens remain uncertain.

[Practical application of the charter of pharmaceutical sales visit]

BACKGROUND

Visits from pharmaceutical representatives are controlled in France by regulations, but also by a Charter of good practice. The goal of this study was to measure compliance to the conditions of this charter by participating pharmaceutical companies.

MATERIAL AND METHODS

An assessment grid was drafted to determine compliance to interdictions and obligations concerning the information provided during visits from pharmaceutical representatives.

RESULTS

We studied 20 visits from pharmaceutical representatives. All of the documents and obligatory information were only provided in 5% of cases. During 80% of these meetings, the pharmaceutical representatives made a comparison with competitor's drugs, which was associated with negative remarks in 44% of cases. The pharmaceutical representatives promoted cases of use outside those, which had received marketing approval in 35%. Gifts or samples were offered at the end of these meetings in 20% of cases. Prohibited practices were observed in a total of 85% of cases.

DISCUSSION

This study shows that meetings are respected by pharmaceutical representatives in terms of regulations related to donations. In opposite, there is a very low compliance concerning the proper use of the drug, whether to provide official documentation, to give information respectful of other pharmaceutical companies or to promote the proper use.

CONCLUSION

Our results suggest that, at present hospital visits by pharmaceutical representatives do not respect the commitments made by the pharmaceutical industry, and do not make it possible to ensure that honest information is provided to favor the proper use of drugs.

[Relationship between benzodiazepines use and falls in the elderly: a multicenter study in three geriatric centers of a university hospital]

INTRODUCTION

Benzodiazepines are widely used in the elderly, but may induce potentially severe iatrogenic events like falls. The analysis of their use is difficult because of the numerous molecules and dosages available. The aim of the present study is to build a tool to monitor their consumption and to evaluate the relation between this consumption and patient's falls reported in three geriatric institutions.

METHODS

Conversion coefficients found in the literature allowed the expression of benzodiazepine action with a unique comparator: diazepam. Benzodiazepine consumption observed during 20 consecutive months was collected and weighted by hospital activity. A correlation between benzodiazepine consumption and the number of falls reported during the same period was researched.

RESULTS

Benzodiazepine consumption expressed in milligrams of diazepam-equivalent per hospitalization day is significantly linked to the number of falls expressed during the same period (R=0.63; p<0.01). However, no statistical bound was found between monthly falls variations and monthly benzodiazepine consumption variations. These results corroborate others published studies: benzodiazepine consumptions are statistically linked to falls, but the reduction of this consumption is of poor predictive value, maybe because of the multifactorial nature of falls.

DISCUSSION AND CONCLUSION

The expression of benzodiazepine consumption in diazepam-equivalent enables one to estimate the general exposition of patients and to compare the use of each molecule. The statistical link between this indicator and a major iatrogenic event like falls makes it a tool worth interest for both clinicians and pharmacists.

Cadaveric volatile organic compounds released by decaying pig carcasses (Sus domesticus L.) in different biotopes

Forensic entomology uses pig carcasses to surrogate human decomposition and to investigate the entomofaunal colonization. Insects communicate with their environment through the use of chemical mediators, which in the case of necrophagous insects, may consist in the cadaveric volatile organic compounds (VOCs) released by the corpse under decomposition. Previous studies have focused on cadaveric VOCs released from human corpses. Nevertheless, studies on human corpses are restricted for many reasons, including ethics. Forensic entomologists use pig as animal model but very few information are available about the decompositional VOCs released by a decaying pig carcass. We here tested a passive sampling technique, the Radiello diffusive sampler, to monitor the cadaveric VOCs released by decomposing pig carcasses in three biotopes (crop field, forest, urban site). A total of 104 chemical compounds, exclusively produced by the decompositional process, were identified by thermal desorption interfaced with gas chromatography and mass spectrometry (TDS-GC-MS). Ninety, 85 and 57 cadaveric VOCs were identified on pig carcasses laying on the agricultural site, the forest biotope and in the urban site, respectively. The main cadaveric VOCs are acids, cyclic hydrocarbons, oxygenated compounds, sulfur and nitrogen compounds. A better knowledge of the smell of death and their volatile constituents may have many applications in forensic sciences.

[Interindividual pharmacokinetic variability in long-term antibiotherapy]

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.

Amino acids in the cytoplasmic C terminus of the parathyroid Ca2+-sensing receptor mediate efficient cell-surface expression and phospholipase C activation

The C-terminal tail of the calcium receptor (CaR) regulates the affinity of the receptor for ligand, desensitization, and membrane localization. To determine the role of specific amino acids in the bovine parathyroid CaR in mediating signal transduction and cell-surface expression, we transfected truncated and mutated CaR cDNAs into HEK-293 cells. The ability of high extracellular [Ca(2+)] ([Ca(2+)](o)) to increase total inositol phosphate (InsP) production, an index of phospholipase C (PLC) activation, was determined. Receptor expression was assessed by immunoblotting and immunocytochemistry. In cells transiently or stably expressing receptors with the C-terminal tail truncated after residue 895 (CaR-(1-895)) or 929 (CaR-(1-929)), raising [Ca(2+)](o) increased InsPs to levels comparable with those of cells expressing wild-type CaRs. There were no PLC responses to high [Ca(2+)](o) (up to 30 mm) in cells expressing CaRs with C-terminal tails of only 3 residues (CaR-(1-866)), even though these receptors were expressed in the membrane. We scanned the residues between Ser(866) and Val(895) using tandem-Ala and single-site mutagenesis. Two point mutants (His(880) --> Ala and Phe(882) --> Ala CaR) showed 50-70% reductions in high [Ca(2+)](o)-induced InsP production. The levels of expression and glycosylation of these mutants were comparable with wild-type CaRs, but both receptors were profoundly retained in intracellular organelles and co-localized with the endoplasmic reticulum marker BiP. This suggested that the signaling defects of these receptors were likely because of defective trafficking of receptors to the cell surface. Modeling of the C-terminal domain of the CaR indicated that His(880) and Phe(882) are situated in a putative alpha-helical structure of 15 amino acids between residues 877 and 891 in the C-terminal tail. Our studies support the idea that specific amino acids, and possibly a unique secondary structure in the C-terminal tail, are required for the efficient targeting of the CaR to the cell surface required for PLC activation.

Nuclear localization of EGF receptor and its potential new role as a transcription factor

Epidermal growth factor receptor (EGFR) has been detected in the nucleus in many tissues and cell lines. However, the potential functions of nuclear EGFR have largely been overlooked. Here we demonstrate that nuclear EGFR is strongly correlated with highly proliferating activities of tissues. When EGFR was fused to the GAL4 DNA-binding domain, we found that the carboxy terminus of EGFR contained a strong transactivation domain. Moreover, the receptor complex bound and activated AT-rich consensus-sequence-dependent transcription, including the consensus site in cyclin D1 promoter. By using chromatin immunoprecipitation assays, we further demonstrated that nuclear EGFR associated with promoter region of cyclin D1 in vivo. EGFR might therefore function as a transcription factor to activate genes required for highly proliferating activities.

Expression of Sonic Hedgehog downstream genes is modified in rat embryos exposed in utero to a distal inhibitor of cholesterol biosynthesis

Holoprosencephaly is a common developmental anomaly of the forebrain and midface, that has been associated with mutations in the Sonic Hedgehog gene, and with perturbations of cholesterol synthesis and metabolism in mammalian embryos. The study presented here was aimed to evaluate the functional relationship between these two causal agents in the genesis of the phenotype. Therefore, we used rat embryos exposed in utero to a distal inhibitor of cholesterol biosynthesis (AY9944) in which we analyzed different Shh-dependent processes, as evaluated by the expression of eight target genes. In addition, to delineate between the impact of cholesterol shortage and/or sterol precursors accumulation on the Shh signaling cascade we exposed rat embryos to AY9944 and we provided complementary diets rich in cholesterol and 7-DHC. At the early-somite stage we observed a reduction of Shh signaling in AY9944 treated embryos, resulting in the definition of a narrower ventral domain. Later in development this reduction of Shh signaling led to a complete interruption of the pathway in the rostral hindbrain and caudal midbrain. Other regions such as the forebrain and the spinal cord appeared less sensitive to the reduction of Shh signaling and interruption of the pathway was only observed in a subset of embryos. Finally, we did provide evidence that 7-DHC accumulation is compatible with normal activity of Shh, as long as cholesterol levels in embryonic tissue is sufficient.

Overexpression of CD44 in pl85(neu)-transfected NIH3T3 cells promotes an up-regulation of hyaluronic acid-mediated membrane-cytoskeleton interaction and cell adhesion

CD44 is a transmembrane glycoprotein known to bind hyaluronic acid (HA) in its extracellular domain and to contain at least one ankyrin-binding site in its cytoplasmic domain. In this study we have examined CD44 expression in a mouse fibroblast cell line transfected with the pl85(neu) oncogene cDNA. The results of RT-PCR and Southern blot analyses reveal that CD44s (CD44 standard form) transcript is expressed in both pl85(neu)-transfected cells and untransfected cells. Using surface iodination, anti-CD44 immunoprecipitation and immuno-binding assays, we have found that the number of CD44s molecules expressed on the surface of pl85(neu)-transfected cells are at least 4.5-fold higher than those detected on untransfected cells. Overexpression of surface CD44s in pl85(neu)-transfected cells results in a dramatic enhancement of HA-mediated cell adhesion. Scatchard plot analysis indicates that CD44s in pl85(neu) transfected cells binds directly and specifically to ankyrin. The binding affinity between CD44s and ankyrin in p185(neu)-transfected cells approximately 0.19 nM) appears to be somewhat higher than that found in the untransfected cells (K(p) approximately 0.30 nM). Double immunofluorescence staining and confocal microscopic analyses indicate that HA induces the HA receptor (i.e. CD44s) to form adhesion plaque-like structures, and causes an accumulation of intracellular ankyrin directly underneath HA receptor (CD44s)-adhesion plaque-like structures in pl85(neu)-transfected cells (but not in untransfected cells). These findings suggest that overexpression of CD44s and up-regulation of CD44s-ankyrin interaction by pl85(neu) oncogene may be one of the pre-requisite steps in regulating tumor cell behavior.