Risk assessment of predicted serum concentrations of bisphenol A in children and adults following treatment with dental composite restoratives, dental sealants, or orthodontic adhesives using physiologically based pharmacokinetic modeling.

Bisphenol A (BPA) is a chemical used to manufacture bisphenol A glycidyl methacrylate (BisGMA). BisGMA has been used for decades in dental composite restoratives, sealants, and adhesives. Based on published studies, exposure to low concentrations of BPA are possible from dental and orthodontic devices. The serum BPA concentrations arising from such devices and oral doses were predicted using a PBPK model in children and adult females based on 1) published extraction data for cured and uncured 3M ESPE Filtek Supreme Ultra Flowable, 3M ESPE Filtek Bulk Fill Restorative, and 3M ESPE Clinpro Sealant and 2) published 20% ethanol/water and water rinsate data following orthodontic application with 3M ESPE Transbond MIP Primer and 3M ESPE Transbond XT Adhesive. Predicted oral exposure to BPA arising from these dental and orthodontic devices is low (median <10 ng/treatment) and predicted serum BPA concentrations were also low (<10-4 nM). Even the maximum predicted exposure in this study (533.2 ng/treatment) yields a margin of exposure of 7.5 relative to the EFSA t-TDI (4 µg/kg-day) and is only 2.8% of the daily BPA exposure for the US population in a 58-kg woman (15,660 ng/day). Therefore, the exposure to BPA arising from the 3M ESPE dental and orthodontic devices evaluated in this study is negligible relative to daily BPA exposure in the general population and these potential BPA sources do not constitute a risk to patients.

Rapid and sensitive detection of bisphenol a from serum matrix.

Bisphenol A (BPA) is an endocrine disrupting compound that may have adverse developmental, reproductive, neurological, and immune system effects. Low-level exposure to BPA is ubiquitous in human populations due to its widespread use in consumer products. Therefore, highly sensitive methods are needed to quantify BPA in various matrices including water, serum, and food products. In this study, we developed a simple, rapid, highly sensitive and specific sensor based on an aptamer probe and AC electrokinetics capacitive sensing method that successfully detected BPA at femto molar (fM) levels, which is an improvement over prior work by a factor of 10. We were able to detect BPA spiked in human serum as well as in maternal and cord blood within 30s. The sensor is responsive to BPA down to femto molar levels, but not to structurally similar compounds including bisphenol F (BPF) or bisphenol S (BPS) even at much higher concentration. Further development of this platform may prove useful in monitoring exposure to BPA and other small molecules in various matrices.

Development of a physiologically based pharmacokinetic model for assessment of human exposure to bisphenol A.

A previously developed physiologically based pharmacokinetic (PBPK) model for bisphenol A (BPA) in adult rhesus monkeys was modified to characterize the pharmacokinetics of BPA and its phase II conjugates in adult humans following oral ingestion. Coupled with in vitro studies on BPA metabolism in the liver and the small intestine, the PBPK model was parameterized using oral pharmacokinetic data with deuterated-BPA (d6-BPA) delivered in cookies to adult humans after overnight fasting. The availability of the serum concentration time course of unconjugated d6-BPA offered direct empirical evidence for the calibration of BPA model parameters. The recalibrated PBPK adult human model for BPA was then evaluated against published human pharmacokinetic studies with BPA. A hypothesis of decreased oral uptake was needed to account for the reduced peak levels observed in adult humans, where d6-BPA was delivered in soup and food was provided prior to BPA ingestion, suggesting the potential impact of dosing vehicles and/or fasting on BPA disposition. With the incorporation of Monte Carlo analysis, the recalibrated adult human model was used to address the inter-individual variability in the internal dose metrics of BPA for the U.S. general population. Model-predicted peak BPA serum levels were in the range of pM, with 95% of human variability falling within an order of magnitude. This recalibrated PBPK model for BPA in adult humans provides a scientific basis for assessing human exposure to BPA that can serve to minimize uncertainties incurred during extrapolations across doses and species.

Bisphenol A and child and youth behaviour: Canadian Health Measures Survey 2007 to 2011.

BACKGROUND: Bisphenol A (BPA) is a synthetic industrial chemical commonly used in consumer products. Results from the Canadian Heath Measures Survey (CHMS) indicate that more than 90% of children and youth aged 6 to 19 have detectable levels of urinary BPA. Childhood concentration levels of BPA have been linked with negative behavioural outcomes. DATA AND METHODS: The data are from the first two cycles (2007 to 2009 and 2009 to 2011) of the CHMS, which collected biomonitoring indicators via spot blood and urine samples. Behavioural outcomes--hyperactivity/inattention, emotional symptoms, conduct problems, peer problems, and prosocial behavior--were assessed with Goodman's Strengths and Difficulties Questionnaire. Geometric mean urinary BPA concentration was examined overall and by demographic and socioeconomic correlates. Six multiple logistic regression analyses were conducted to investigate associations between childhood BPA concentrations and risk status for each outcome. RESULTS: Children aged 6 to 8 had higher BPA concentrations than did older children and youth. Concentrations were significantly higher among children and youth exposed to second-hand smoke every day or almost every day and those in low or lower-middle income households. Higher BPA concentrations were associated with increased odds of hyperactivity among girls and lower prosocial behaviour among boys. INTERPRETATION: These findings suggest an association between urinary BPA concentration and children's behavioural outcomes.

Bioequivalence, Food Effect, and Steady-State Assessment of Dapagliflozin/Metformin Extended-release Fixed-dose Combination Tablets Relative to Single-component Dapagliflozin and Metformin Extended-release Tablets in Healthy Subjects.

PURPOSE: Simplification of therapeutic regimens for patients with type 2 diabetes mellitus can provide convenience that leads to improved compliance. Dapagliflozin/metformin extended-release (XR) fixed-dose combination (FDC) tablets offer the convenience of once-daily dosing. Two pharmacokinetic (PK) studies were conducted to establish bioequivalence for 2 doses of dapagliflozin/metformin XR FDC versus the same dosage of the individual component (IC) tablets in healthy adults. METHODS: Two open-label, randomized, 4-period, 4-arm crossover studies were conducted to assess the bioequivalence and PK properties of dapagliflozin and metformin FDCs in healthy subjects under fed and fasting conditions. Participants received single oral doses or once-daily dosing of dapagliflozin/metformin XR (5 mg/500 mg [study 1] or 10 mg/1000 mg [study 2]) for 4 days in an FDC formulation or corresponding strengths of IC tablets. FINDINGS: For both of the studies, dapagliflozin and metformin 5 mg/500 mg or 10 mg/1000 mg FDC tablets were bioequivalent to the respective IC tablets. The 90% CIs of the ratio of the adjusted geometric means for all key PK parameters (Cmax, AUC0-T, and AUC0-∞) were contained within the predefined 0.80 to 1.25 range to conclude bioequivalence for both dapagliflozin and metformin. Once-daily dosing to steady state of each FDC tablet had no effect on the PK properties of dapagliflozin or metformin. When the FDCs were administered with a light-fat meal, there was no effect on metformin PK values and only a modest, nonclinically meaningful effect on dapagliflozin PK values. There were no safety or tolerability concerns. IMPLICATIONS: Bioequivalence of the FDCs of dapagliflozin/metformin XR and the ICs was established, and no safety issues of clinical concern were raised.

Associations between socioeconomic status and environmental toxicant concentrations in adults in the USA: NHANES 2001-2010.

Low level chronic exposure to toxicants is associated with a range of adverse health effects. Understanding the various factors that influence the chemical burden of an individual is of critical importance to public health strategies. We investigated the relationships between socioeconomic status (SES) and bio-monitored chemical concentration in five cross-sectional waves of the U.S. National Health and Nutrition Examination Survey (NHANES). We utilised adjusted linear regression models to investigate the association between 179 toxicants and the poverty income ratio (PIR) for five NHANES waves. We then selected a subset of chemicals associated with PIR in 3 or more NHANES waves and investigated potential mediating factors using structural equation modelling. PIR was associated with 18 chemicals in 3 or more NHANES waves. Higher SES individuals had higher burdens of serum and urinary mercury, arsenic, caesium, thallium, perfluorooctanoic acid, perfluorononanoic acid, mono(carboxyoctyl) phthalate and benzophenone-3. Inverse associations were noted between PIR and serum and urinary lead and cadmium, antimony, bisphenol A and three phthalates (mono-benzyl, mono-isobutyl, mono-n-butyl). Key mediators included fish and shellfish consumption for the PIR, mercury, arsenic, thallium and perfluorononanoic acid associations. Sunscreen use was an important mediator in the benzophenone-3/PIR relationship. The association between PIR and cadmium or lead was partially mediated by smoking, occupation and diet. These results provide a comprehensive analysis of exposure patterns as a function of socioeconomic status in US adults, providing important information to guide future public health remediation measures to decrease toxicant and disease burdens within society.

Enantioselective separation and determination of adrafinil and modafinil on Chiralcel OJ-H column in rat serum and urine using solid-phase extraction followed by HPLC.

A simple and rapid normal-phase HPLC method for enantiospecific separation of a psychostimulant, adrafinil (ADL), and its metabolite modafinil (MDL) in rat serum and urine was developed. The separation was accomplished on a normal-phase polysaccharide stationary phase Chiralcel OJ-H using n-hexane-ethanol (62:38 v/v) as a mobile phase at a flow rate of 1.0 mL/min. Detection was carried out at 225 nm using a photo diode array (PDA) detector. The elution order of the enantiomers was determined by a polarimeter connected in series with the PDA. ADL and its metabolite were recovered from rat serum and urine by solid phase extraction using Oasis HLB cartridges and the mean recoveries were >or=80%. The enantiomers were eluted within 15 min without any interference from endogenous substances. The calibration curves were linear (r(2) > 0.998) in the concentration range of 1.20-500 microg/mL for ADL and MDL. The assay was specific, accurate, precise and reproducible (intra- and inter-day precisions RSDs <7.2%). ADL in rat serum was stable over three freeze-thaw cycles at ambient temperature for 4 h. The method was successfully applied to pharmacokinetic studies of adrafinil after an oral administration to rats.

Positive- and negative-ion mass spectrometry of diphenylmethane antihistaminics and their analogues and rapid clean-up of them from biological samples.

Positive-ion electron impact (PIEI), positive-ion chemical ionization (PICI) and negative-ion chemical ionization (NICI) mass spectra are presented for 15 compounds of diphenylmethane antihistaminics and their analogues, and each fragmentation pathway was analyzed. In the PIEI mode, molecular peaks were very small or missing for most compounds. Peaks at m/z 58, due to a dimethylaminomethyl group liberated, constituted base peaks in five compounds. Peaks at m/z 165 and/or 167, due to diaromatic rings plus a methyl group, appeared in most compounds. In the PICI mode, peaks due to M+H and M+C2H5 appeared in all compounds. Peaks due to diaromatic rings plus a methyl or ethyl group constituted base peaks in five compounds, which had an ether bond in their structures. In the NICI mode, anions at m/z M-H appeared in most compounds. Peaks at m/z 35 were observed for compounds having a chlorine group in their structures. Detection limits for total ion monitoring of these compounds were 20-50 ng on column in the PIEI mode, 100-200 ng in the PICI mode and 500-1000 ng in the NICI mode. A rapid and simple clean-up procedure of these drugs with use of Sep-Pak C18 cartridges is also presented. The drugs could be detected by gas chromatography with DB-1 and DB-17 capillary columns with satisfactory separation from impurities in their underivatized forms. The recovery of the drugs, which had been added to whole blood and urine, was more than 60% except for meclizine.