Pharmacokinetics and safety of a single dose of telavancin in pediatric subjects 2-17 years of age

Antimicrobial resistance increases infection morbidity in both adults and children, necessitating the development of new therapeutic options. Telavancin, an antibiotic approved in the United States for certain bacterial infections in adults, has not been examined in pediatric patients. The objectives of this study were to evaluate the short-term safety and pharmacokinetics (PK) of a single intravenous infusion of telavancin in pediatric patients. Single-dose safety and PK of 10 mg/kg telavancin was investigated in pediatric subjects >12 months to ≤17 years of age with known or suspected bacterial infection. Plasma was collected up to 24-h post-infusion and analyzed for concentrations of telavancin and its metabolite for noncompartmental PK analysis. Safety was monitored by physical exams, vital signs, laboratory values, and adverse events following telavancin administration. Twenty-two subjects were enrolled: 14 subjects in Cohort 1 (12-17 years), 7 subjects in Cohort 2 (6-11 years), and 1 subject in Cohort 3 (2-5 years). A single dose of telavancin was well-tolerated in all pediatric age cohorts without clinically significant effects. All age groups exhibited increased clearance of telavancin and reduced exposure to telavancin compared to adults, with mean peak plasma concentrations of 58.3 µg/mL (Cohort 1), 60.1 µg/mL (Cohort 2), and 53.1 µg/mL (Cohort 3). A 10 mg/kg dose of telavancin was well tolerated in pediatric subjects. Telavancin exposure was lower in pediatric subjects compared to adult subjects. Further studies are needed to determine the dose required in phase 3 clinical trials in pediatrics.

Hepatic pyruvate and alanine metabolism are critical and complementary for maintenance of antioxidant capacity and resistance to oxidative insult

OBJECTIVE

Mitochondrial pyruvate is a critical intermediary metabolite in gluconeogenesis, lipogenesis, and NADH production. As a result, the mitochondrial pyruvate carrier (MPC) complex has emerged as a promising therapeutic target in metabolic diseases. Clinical trials are currently underway. However, recent in vitro data indicate that MPC inhibition diverts glutamine/glutamate away from glutathione synthesis and toward glutaminolysis to compensate for loss of pyruvate oxidation, possibly sensitizing cells to oxidative insult. Here, we explored this in vivo using the clinically relevant acetaminophen (APAP) overdose model of acute liver injury, which is driven by oxidative stress.

METHODS

We used pharmacological and genetic approaches to inhibit MPC2 and alanine aminotransferase 2 (ALT2), individually and concomitantly, in mice and cell culture models and determined the effects on APAP hepatotoxicity.

RESULTS

We found that MPC inhibition sensitizes the liver to APAP-induced injury in vivo only with concomitant loss of alanine aminotransferase 2 (ALT2). Pharmacological and genetic manipulation of neither MPC2 nor ALT2 alone affected APAP toxicity, but liver-specific double knockout (DKO) significantly worsened APAP-induced liver damage. Further investigation indicated that DKO impaired glutathione synthesis and increased urea cycle flux, consistent with increased glutaminolysis, and these results were reproducible in vitro. Finally, induction of ALT2 and post-treatment with dichloroacetate both reduced APAP-induced liver injury, suggesting new therapeutic avenues.

CONCLUSIONS

Increased susceptibility to APAP toxicity requires loss of both the MPC and ALT2 in vivo, indicating that MPC inhibition alone is insufficient to disrupt redox balance. Furthermore, the results from ALT2 induction and dichloroacetate in the APAP model suggest new metabolic approaches to the treatment of liver damage.

Hands-Free Analytical Urine Testing Technology Validated for Drug-Facilitated Crime Investigations

Forensic laboratories need quick and simple technology to improve turnaround times, while delivering reliable results. The goal of this study is first to create a simplified workflow to meet new Academy Standards Board requirements for urine testing in drug-facilitated crime investigations and, second, to create "ready-to-go", "hands-free" testing technology to further streamline analytical procedures. A first of its kind, the ToxBox forensic test kit is used to validate a single analytical procedure for opioids, benzodiazepines, cannabinoids, antidepressants, and several other drug classes. Method performance indicators follow accreditation requirements and include accuracy, precision, measurement uncertainty, calibration models, reportable range, sensitivity, specificity, carryover, interference, ion suppression/enhancement, and analyte stability. "Hands-free" testing platforms require the use of new suspended-state technology to stabilize NIST-traceable standards premanufactured at precise concentrations in the presence of sample preparation reagents. By suspending all reaction components in the solid state, with air gaps between the phases, reference standards and process controls are built in a "ready-to-go" format and stabilized for long-term storage in the presence of a sample matrix, β-d-glucuronidase, and enzymatic buffers. "Hands-free" test kits are removed from storage, incubated at either ambient temperature or 60 °C, and assayed using validated methods. This is the first example of how complex forensic testing workflows can be streamlined with new "hands-free" testing strategies to meet analytical challenges associated with quantitative and confirmatory analyses.

A longitudinal study of SARS-CoV-2 antibody seroprevalence and mitigation behaviors among college students at an Arkansas University

Objective: Assess university students' SARS-CoV-2 antibody seroprevalence and mitigation behaviors over time. Participants: Randomly selected college students (N = 344) in a predominantly rural Southern state. Methods: Participants provided blood samples and completed self-administered questionnaires at three timepoints over the academic year. Adjusted odds ratios and 95% confidence intervals were estimated from logistic regression analyses. Results: SARS-CoV-2 antibody seroprevalence was 18.2% in September 2020, 13.1% in December, and 45.5% in March 2021 (21% for those with no vaccination history). SARS-CoV-2 antibody seroprevalence was associated with large social gatherings, staying local during the summer break, symptoms of fatigue or rhinitis, Greek affiliation, attending Greek events, employment, and using social media as the primary COVID-19 information source. In March 2021, seroprevalence was associated with receiving at least one dose of a COVID-19 vaccination. Conclusion: SARS-CoV-2 seroprevalence was higher in this population of college students than previous studies. Results can assist leaders in making informed decisions as new variants threaten college campuses.

Rural Research Network to engage rural and minority community members in translational research

Background

To address the high prevalence of health disparities and lack of research opportunities among rural and minority communities, the University of Arkansas for Medical Sciences (UAMS) developed the Rural Research Network in January 2020.

Aim

The aim of this report is to describe our process and progress in developing a rural research network. The Rural Research Network provides a platform to expand research participation opportunities to rural Arkansans, many of whom are older adults, low-income individuals, and underrepresented minority populations.

Methods

The Rural Research Network leverages existing UAMS Regional Programs family medicine residency clinics within an academic medical center.

Results

Since the inception of the Rural Research Network, research infrastructure and processes have been built within the regional sites. Twelve diverse studies have been implemented with recruitment and data collection from 9248 participants, and 32 manuscripts have been published with residents and faculty from the regional sites. Most studies were able to recruit Black/African American participants at or above a representative sample.

Conclusions

As the Rural Research Network matures, the types of research will expand in parallel with the health priorities of Arkansas.

Relevance to Patients

The Rural Research Network demonstrates how Cancer Institutes and sites funded by a Clinical and Translational Science Award can collaborate to expand research capacity and increase opportunities for research among rural and minority communities.

Solithromycin in Children and Adolescents With Community-acquired Bacterial Pneumonia

BACKGROUND

Solithromycin is a new macrolide-ketolide antibiotic with potential effectiveness in pediatric community-acquired bacterial pneumonia (CABP). Our objective was to evaluate its safety and effectiveness in children with CABP.

METHODS

This phase 2/3, randomized, open-label, active-control, multicenter study randomly assigned solithromycin (capsules, suspension or intravenous) or an appropriate comparator antibiotic in a 3:1 ratio (planned n = 400) to children 2 months to 17 years of age with CABP. Primary safety endpoints included treatment-emergent adverse events (AEs) and AE-related drug discontinuations. Secondary effectiveness endpoints included clinical improvement following treatment without additional antimicrobial therapy.

RESULTS

Unrelated to safety, the sponsor stopped the trial prior to completion. Before discontinuation, 97 participants were randomly assigned to solithromycin (n = 73) or comparator (n = 24). There were 24 participants (34%, 95% CI, 23%-47%) with a treatment-emergent AE in the solithromycin group and 7 (29%, 95% CI, 13%-51%) in the comparator group. Infusion site pain and elevated liver enzymes were the most common related AEs with solithromycin. Study drug was discontinued due to AEs in 3 subjects (4.3%) in the solithromycin group and 1 (4.2%) in the comparator group. Forty participants (65%, 95% CI, 51%-76%) in the solithromycin group achieved clinical improvement on the last day of treatment versus 17 (81%, 95% CI, 58%-95%) in the comparator group. The proportion achieving clinical cure was 60% (95% CI, 47%-72%) and 68% (95% CI, 43%-87%) for the solithromycin and comparator groups, respectively.

CONCLUSIONS

Intravenous and oral solithromycin were generally well-tolerated and associated with clinical improvement in the majority of participants treated for CABP.

The Spice of Death: Sudden Cardiac Arrest After Novel Psychoactive Substance Exposure

ABSTRACT

Novel psychoactive substances (NPSs), commonly referred to as "K2" or "spice," are a relatively new toxicology challenge for pediatricians. Adolescents often incorrectly believe that these drugs are safe and can be used without major adverse effects. Although recent legislation attempts to ensure that these drugs are not commercially available, many are able to be purchased online as "not fit for human consumption" or under various misnomers such "incense." In addition, there is a wide chemical variation among these substances, making regulation challenging. Standard urine drug screens test for tetrahydrocannabinol, which may not cross-react with synthetic substances, making NPS poisonings difficult to diagnose. We report a case of fatal cardiac arrest in a 16-year-old adolescent boy temporally associated with use of the NPS, 5F-ADB. The case illustrates the dangerous consequences that these unregulated substances pose to users, as well as the need for the consideration of comprehensive toxicological testing in patients with a history of substance use and sudden cardiac arrest, despite a negative drug screen.

Exogenous phosphatidic acid reduces acetaminophen-induced liver injury in mice by activating hepatic interleukin-6 signaling through inter-organ crosstalk

We previously demonstrated that endogenous phosphatidic acid (PA) promotes liver regeneration after acetaminophen (APAP) hepatotoxicity. Here, we hypothesized that exogenous PA is also beneficial. To test that, we treated mice with a toxic APAP dose at 0 h, followed by PA or vehicle (Veh) post-treatment. We then collected blood and liver at 6, 24, and 52 h. Post-treatment with PA 2 h after APAP protected against liver injury at 6 h, and the combination of PA and N-acetyl-l-cysteine (NAC) reduced injury more than NAC alone. Interestingly, PA did not affect canonical mechanisms of APAP toxicity. Instead, transcriptomics revealed that PA activated interleukin-6 (IL-6) signaling in the liver. Consistent with that, serum IL-6 and hepatic signal transducer and activator of transcription 3 (Stat3) phosphorylation increased in PA-treated mice. Furthermore, PA failed to protect against APAP in IL-6-deficient animals. Interestingly, IL-6 expression increased 18-fold in adipose tissue after PA, indicating that adipose is a source of PA-induced circulating IL-6. Surprisingly, however, exogenous PA did not alter regeneration, despite the importance of endogenous PA in liver repair, possibly due to its short half-life. These data demonstrate that exogenous PA is also beneficial in APAP toxicity and reinforce the protective effects of IL-6 in this model.

Short-Term Safety of Repeated Acetaminophen Use in Patients With Compensated Cirrhosis

Current guidelines recommend restricting acetaminophen (APAP) use in patients with cirrhosis, but evidence to support that recommendation is lacking. Prior studies focused on pharmacokinetics (PK) of APAP in cirrhosis but did not rigorously examine clinical outcomes, sensitive biomarkers of liver damage, or serum APAP‐protein adducts, which are a specific marker of toxic bioactivation. Hence, the goal of this pilot study was to test the effects of regularly scheduled APAP dosing in a well‐defined compensated cirrhosis group compared to control subjects without cirrhosis, using the abovementioned outcomes. After a 2‐week washout, 12 subjects with and 12 subjects without cirrhosis received 650 mg APAP twice per day (1.3 g/day) for 4 days, followed by 650 mg on the morning of day 5. Patients were assessed in‐person at study initiation (day 1) and on days 3 and 5. APAP‐protein adducts and both conventional (alanine aminotransferase) and sensitive (glutamate dehydrogenase [GLDH], full‐length keratin 18 [K18], and total high‐mobility group box 1 protein) biomarkers of liver injury were measured in serum on the mornings of days 1, 3, and 5, with detailed PK analysis of APAP, metabolites, and APAP‐protein adducts throughout day 5. No subject experienced adverse clinical outcomes. GLDH and K18 were significantly different at baseline but did not change in either group during APAP administration. In contrast, clearance of APAP‐protein adducts was dramatically delayed in the cirrhosis group. Minor differences for other APAP metabolites were also detected. Conclusion: Short‐term administration of low‐dose APAP (650 mg twice per day, <1 week) is likely safe in patients with compensated cirrhosis. These data provide a foundation for future studies to test higher doses, longer treatment, and subjects who are decompensated, especially in light of the remarkably delayed adduct clearance in subjects with cirrhosis.

Arkansans' Preferred COVID-19 Testing Locations

Introduction:

A contributing factor to racial and ethnic disparities during the COVID-19 pandemic may be the accessibility and acceptability of COVID-19 testing. Previous studies found that access to testing has not been equitable across several sociodemographic indicators. This study documents the preferred testing locations and examines differences across sociodemographic factors with a specific focus on race and ethnicity.

Methods:

This study includes a primary analysis of cross-sectional data using a self-administered digital survey distributed to Arkansas residents using ARresearch, a volunteer research participant registry. The survey had 1288 responses, and 1221 met eligibility criteria for inclusion in the survey. Participants provided sociodemographic information and were asked to select up to 3 preferred testing locations from 12 options. Chi-square tests assessed differences in testing site preference across relevant sociodemographic groups.

Results:

Participants preferred drive-through clinics as their top location for COVID-19 testing, with 55% reporting this was their preferred method of testing. This pattern was consistent across all comparison groups (ie, age, sex, race/ethnicity, education, insurance status). Significant differences in testing location preference were observed across age, race and ethnicity, and education, with the most differences observed across race and ethnicity.

Conclusion:

This study reveals that race and ethnicity are important to consider when deciding where to offer COVID-19 testing. The preferences for testing locations among the most vulnerable demographics will be used to develop targeted responses aimed at eliminating disparities in COVID-19 in Arkansas.

Perceived Barriers to COVID-19 Testing

(1) Background: Prior studies have documented that access to testing has not been equitable across all communities in the US, with less testing availability and lower testing rates documented in rural counties and lower income communities. However, there is limited understanding of the perceived barriers to coronavirus disease 2019 (COVID-19) testing. The purpose of this study was to document the perceived barriers to COVID-19 testing. (2) Methods: Arkansas residents were recruited using a volunteer research participant registry. Participants were asked an open-ended question regarding their perceived barriers to testing. A qualitative descriptive analytical approach was used. (3) Results: Overall, 1221 people responded to the open-ended question. The primary barriers to testing described by participants were confusion and uncertainty regarding testing guidelines and where to go for testing, lack of accessible testing locations, perceptions that the nasal swab method was too painful, and long wait times for testing results. (4) Conclusions: This study documents participant reported barriers to COVID-19 testing. Through the use of a qualitative descriptive method, participants were able to discuss their concerns in their own words. This work provides important insights that can help public health leaders and healthcare providers with understanding and mitigating barriers to COVID-19 testing.

Dissemination Protocol for Community-Based Participatory Research Partnerships with Marshallese Pacific Islanders in Arkansas

BACKGROUND

The Pacific Islander population in the United States (U.S.) has rapidly increased since 2000, especially in southern states like Arkansas where the largest population of Marshallese in the continental U.S. reside. The Marshallese community faces significant health disparities with high prevalence of diabetes, obesity, obesity-related cancers, and other chronic conditions.

OBJECTIVES

Researchers have utilized a community-based participatory research (CBPR) approach that fully engages Marshallese stakeholders in research to address the community's health disparities. Sharing research findings with participants and stakeholders is a core principle of CBPR.

METHODS

This manuscript describes the methods that the academic-community research partnership used to develop a dissemination protocol for sharing results from multiple pilot studies and randomized control trials. Examples and details of specific activities that resulted from putting the dissemination plan in action are presented.

CONCLUSIONS

Implementation of CBPR principles ensures that researchers fully engage stakeholders in all aspects of research, including the dissemination of study results. This manuscript describes the dissemination protocol for an academic- community research partnership with the Marshallese community and provides a practical example for how to implement successful community-engaged dissemination.

Pre-treatment twice with liposomal clodronate protects against acetaminophen hepatotoxicity through a pre-conditioning effect

BACKGROUND AND AIM

Acetaminophen (APAP) overdose is a major cause of acute liver injury, but the role of macrophages in propagation of the hepatotoxicity is controversial. Early research revealed that macrophage inhibitors protect against APAP injury. However, later work demonstrated that macrophage ablation by acute pre-treatment with liposomal clodronate (LC) exacerbates the toxicity. To our surprise, during other studies, we observed that pre-treatment twice with LC seemed to protect against APAP hepatotoxicity, in contrast to acute pre-treatment. The aim of this study was to confirm that observation and to explore the mechanisms.

METHODS

We treated mice with empty liposomes (LE) or LC twice per week for 1 week before APAP overdose and collected blood and liver tissue at 0, 2, and 6 h post-APAP. We then measured liver injury (serum ALT activity, histology), APAP bioactivation (total glutathione, APAP-protein adducts), oxidative stress (oxidized glutathione [GSSG]), glutamate cysteine-ligase subunit c (Gclc) mRNA, and nuclear factor erythroid 2-related factor (Nrf2) immunofluorescence. We also confirmed ablation of macrophages by F4/80 immunohistochemistry.

RESULTS

Pre-treatment twice with LC dramatically reduced F4/80 staining, protected against liver injury, and reduced oxidative stress at 6 h post-APAP, without affecting APAP bioactivation. Importantly, Gclc mRNA was higher in the LC group at 0 h and total glutathione was higher at 2 h, indicating accelerated glutathione re-synthesis after APAP overdose due to greater basal glutamate-cysteine ligase. Oxidative stress was lower in the LC groups at both time points. Finally, total Nrf2 immunofluorescence was higher in the LC group.

CONCLUSIONS

We conclude that multiple pre-treatments with LC protect against APAP by accelerating glutathione re-synthesis through glutamate-cysteine ligase. Investigators using two or possibly more LC pre-treatments to deplete macrophages, including peritoneal macrophages, should be aware of this possible confounder.

Nitrosative Stress and Lipid Homeostasis as a Mechanism for Zileuton Hepatotoxicity and Resistance in Genetically Sensitive Mice

Zileuton is an orally active inhibitor of leukotriene synthesis for maintenance treatment of asthma, for which clinical usage has been associated with idiosyncratic liver injury. Mechanistic understanding of zileuton toxicity is hampered by the rarity of the cases and lack of an animal model. A promising model for mechanistic study of rare liver injury is the Diversity Outbred (J:DO) mouse population, with genetic variation similar to that found in humans. In this study, female DO mice were administered zileuton or vehicle daily for 7 days (i.g.). Serum liver enzymes were elevated in the zileuton group, with marked interindividual variability in response. Zileuton exposure-induced findings in susceptible DO mice included microvesicular fatty change, hepatocellular mitosis, and hepatocellular necrosis. Inducible nitric oxide synthase and nitrotyrosine abundance were increased in livers of animals with necrosis and those with fatty change, implicating nitrosative stress as a possible injury mechanism. Conversely, DO mice lacking adverse liver pathology following zileuton exposure experienced decreased hepatic concentrations of resistin and increased concentrations of insulin and leptin, providing potential clues into mechanisms of toxicity resistance. Transcriptome pathway analysis highlighted mitochondrial dysfunction and altered fatty acid oxidation as key molecular perturbations associated with zileuton exposure, and suggested that interindividual differences in cytochrome P450 metabolism, glutathione-mediated detoxification, and farnesoid X receptor signaling may contribute to zileuton-induced liver injury (ZILI). Taken together, DO mice provided a platform for investigating mechanisms of toxicity and resistance in context of ZILI which may lead to targeted therapeutic interventions.

Advances in biomarker development in acetaminophen toxicity

Acetaminophen liver injury is the most common cause of acute liver injury in the United States and several other countries. Diagnosis of acetaminophen-induced acute liver injury in the clinic is challenging due to the lack of validated and specific biomarkers. The following chapter provides an overview of recent advances evaluating candidate biomarkers in development for acetaminophen acute liver injury. Relationships of biomarkers to mechanisms of acetaminophen toxicity and their potential role in confirming the diagnosis and/or predicting evolving toxicity are addressed.

Early acetaminophen-protein adducts predict hepatotoxicity following overdose (ATOM-5)

BACKGROUND & AIMS

Acetaminophen-protein adducts are specific biomarkers of toxic acetaminophen (paracetamol) metabolite exposure. In patients with hepatotoxicity (alanine aminotransferase [ALT] >1,000 U/L), an adduct concentration ≥1.0 nmol/ml is sensitive and specific for identifying cases secondary to acetaminophen. Our aim was to characterise acetaminophen-protein adduct concentrations in patients following acetaminophen overdose and determine if they predict toxicity.

METHODS

We performed a multicentre prospective observational study, recruiting patients 14 years of age or older with acetaminophen overdose regardless of intent or formulation. Three serum samples were obtained within the first 24 h of presentation and analysed for acetaminophen-protein adducts. Acetaminophen-protein adduct concentrations were compared to ALT and other indicators of toxicity.

RESULTS

Of the 240 patients who participated, 204 (85%) presented following acute ingestions, with a median ingested dose of 20 g (IQR 10-40), and 228 (95%) were treated with intravenous acetylcysteine at a median time of 6 h (IQR 3.5-10.5) post-ingestion. Thirty-six (15%) patients developed hepatotoxicity, of whom 22 had an ALT ≤1,000 U/L at the time of initial acetaminophen-protein adduct measurement. Those who developed hepatotoxicity had a higher initial acetaminophen-protein adduct concentration compared to those who did not, 1.63 nmol/ml (IQR 0.76-2.02, n = 22) vs. 0.26 nmol/ml (IQR 0.15-0.41; n = 204; p <0.0001), respectively. The AUROC for hepatotoxicity was 0.98 (95% CI 0.96-1.00; n = 226; p <0.0001) with acetaminophen-protein adduct concentration and 0.89 (95% CI 0.82-0.96; n = 219; p <0.0001) with ALT. An acetaminophen-protein adduct concentration of 0.58 nmol/ml was 100% sensitive and 91% specific for identifying patients with an initial ALT ≤1,000 U/L who would develop hepatotoxicity. Adding acetaminophen-protein adduct concentrations to risk prediction models improved prediction of hepatotoxicity to a level similar to that obtained by more complex models.

CONCLUSION

Acetaminophen-protein adduct concentration on presentation predicted which patients with acetaminophen overdose subsequently developed hepatotoxicity, regardless of time of ingestion. An adduct threshold of 0.58 nmol/L was required for optimal prediction.

LAY SUMMARY

Acetaminophen poisoning is one of the most common causes of liver injury. This study examined a new biomarker of acetaminophen toxicity, which measures the amount of toxic metabolite exposure called acetaminophen-protein adduct. We found that those who developed liver injury had a higher initial level of acetaminophen-protein adducts than those who did not.

CLINICAL TRIAL REGISTRATION

Australian Toxicology Monitoring (ATOM) Study-Australian Paracetamol Project: ACTRN12612001240831 (ANZCTR) Date of registration: 23/11/2012.

Acute Liver Failure of unclear cause? Acetaminophen-protein adducts make the diagnosis

Acetaminophen poisoning remains a leading cause of acute liver failure. Some cases may be difficult to diagnose when clinical findings are equivocal, the patient's history is misleading or incomplete, or the acetaminophen concentration is low or undetectable at arrival to care. We describe a case of a medically complicated young child whose acute liver failure had two of these features. Measurement of acetaminophen-protein adducts confirmed acetaminophen as the primary cause of her liver failure.

Population Pharmacokinetic Modeling of Acetaminophen Protein Adducts in Adults and Children

Acetaminophen protein adducts (adducts) are a well-established biomarker to diagnose acetaminophen toxicity. To date, the quantitative relationship between acetaminophen exposure, which drives adduct formation, and adduct exposure remains to be established. Our study characterized the adduct formation and disposition in adults using the approach of population parent-metabolite modeling. It demonstrated formation-limited pharmacokinetics (PK) for adducts in healthy subjects. This finding expands the existing knowledge on adduct PK that showed an apparent long elimination half-life. We then allometrically scaled the adduct PK model to children, simulated the adduct profiles, and compared these simulated profiles with those observed in an independent cohort of children. The scaled model significantly overpredicted the adduct concentrations in children early on in treatment and underpredicted concentrations following repeated acetaminophen doses. These results suggest that children demonstrate different adduct PK behavior from that of adults, most likely because of increased reactive metabolite detoxification in children. In summary, we described the first PK model linking acetaminophen and acetaminophen protein adduct concentrations, which provides a semimechanistic understanding of varying profiles of adduct exposure in adults and children.

Characterizing health researcher barriers to sharing results with study participants

INTRODUCTION

Research participants want to receive results from studies in which they participate. However, health researchers rarely share the results of their studies beyond scientific publication. Little is known about the barriers researchers face in returning study results to participants.

METHODS

Using a mixed-methods design, health researchers (N = 414) from more than 40 US universities were asked about barriers to providing results to participants. Respondents were recruited from universities with Clinical and Translational Science Award programs and Prevention Research Centers.

RESULTS

Respondents reported the percent of their research where they experienced each of the four barriers to disseminating results to participants: logistical/methodological, financial, systems, and regulatory. A fifth barrier, investigator capacity, emerged from data analysis. Training for research faculty and staff, promotion and tenure incentives, and funding agencies supporting dissemination of results to participants were solutions offered to overcoming barriers.

CONCLUSIONS

Study findings add to literature on research dissemination by documenting health researchers' perceived barriers to sharing study results with participants. Implications for policy and practice suggest that additional resources and training could help reduce dissemination barriers and increase the return of results to participants.

Paradoxical Patterns of Sinusoidal Obstruction Syndrome-Like Liver Injury in Aged Female CD-1 Mice Triggered by Cannabidiol-Rich Cannabis Extract and Acetaminophen Co-Administration

The goal of this study was to investigate the potential for a cannabidiol-rich cannabis extract (CRCE) to interact with the most common over-the-counter drug and the major known cause of drug-induced liver injury–acetaminophen (APAP)–in aged female CD-1 mice. Gavaging mice with 116 mg/kg of cannabidiol (CBD) [mouse equivalent dose (MED) of 10 mg/kg of CBD] in CRCE delivered with sesame oil for three consecutive days followed by intraperitoneally (i.p.) acetaminophen (APAP) administration (400 mg/kg) on day 4 resulted in overt toxicity with 37.5% mortality. No mortality was observed in mice treated with 290 mg/kg of CBD+APAP (MED of 25 mg/kg of CBD) or APAP alone. Following CRCE/APAP co-administration, microscopic examination revealed a sinusoidal obstruction syndrome-like liver injury–the severity of which correlated with the degree of alterations in physiological and clinical biochemistry end points. Mechanistically, glutathione depletion and oxidative stress were observed between the APAP-only and co-administration groups, but co-administration resulted in much greater activation of c-Jun N-terminal kinase (JNK). Strikingly, these effects were not observed in mice gavaged with 290 mg/kg CBD in CRCE followed by APAP administration. These findings highlight the potential for CBD/drug interactions, and reveal an interesting paradoxical effect of CBD/APAP-induced hepatotoxicity.

Acetaminophen Protein Adducts in Hospitalized Children Receiving Multiple Doses of Acetaminophen

Previous reports have questioned the safety of multiple doses of acetaminophen administered to ill children. Acetaminophen protein adducts (adducts) are a biomarker of acetaminophen‐induced liver injury and reflect the oxidative metabolism of acetaminophen, a known mechanism in acetaminophen toxicity. In this prospective observational study, we analyzed adduct concentrations in 1034 blood samples obtained from 181 hospitalized children (1 to 18 years inclusive) who received 2 or more doses of acetaminophen. Linear regression analysis showed that serum adduct concentrations increased as a function of the cumulative acetaminophen dose, which could be attributed, in part, to a long half‐life of adducts (2.17 ± 1.04 days [mean ± standard deviation]) in children. However, few patients (2%) were found to have adduct concentrations higher than 1.0 nmol/mL, a previously identified toxicity cut point for the diagnosis of acetaminophen‐induced liver injury in patients with alanine aminotransferase values exceeding 1000 IU/L. A small cohort of patients with suspected infection was noted to show higher adduct concentrations. In addition, adduct concentrations showed a stronger correlation with cumulative acetaminophen doses in adolescents compared with children (R² = 0.41 vs 0.26). No other covariates (body weight, body mass index z score, sex, race, or surgery) remarkably correlated with adduct elevation. In summary, low levels of adducts can be detected in hospitalized children receiving multiple doses of acetaminophen, and adduct levels correlate with cumulative acetaminophen dose.

Impaired Driving Associated with the Synthetic Cannabinoid 5f-Adb

Synthetic marijuana compounds are more potent than Δ9-tetrahydrocannabinol (∆9-THC) and are known to produce a wide variety of clinical symptoms including cardiac toxicity, seizures, and death. Erratic driving by a 45 y/o male was witnessed in the fall of 2017 and roadside evaluation of the driver by the responding law enforcement officer concluded that the driver was intoxicated. Comprehensive analysis of the cigarettes by gas chromatography-mass spectrometry detected the synthetic cannabinoid 5-fluoro-ADB (5F-ADB or 5F-MDMB-PINACA). Validated forensic liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods were used to detect the 5-fluoro ADB metabolite 7 (26.37 ng/mL) in the driver's blood sample. No other drugs were detected. This case report is one of the first to conclusively show that designer synthetic cannabinoids, commonly referred to as "K2" and "Spice", can significantly impair driving at relatively low concentrations.

Health researchers' experiences, perceptions and barriers related to sharing study results with participants

BACKGROUND

Although research participants are generally interested in receiving results from studies in which they participate, health researchers rarely communicate study findings to participants. The present study was designed to provide opportunity for a broad group of health researchers to describe their experiences and concerns related to sharing results (i.e. aggregate study findings) with research participants.

METHODS

We used a mixed-methods concurrent triangulation design, relying on an online survey to capture health researchers' experiences, perceptions and barriers related to sharing study results with participants. Respondents were health researchers who conduct research that includes the consent of human subjects and hold a current appointment at an accredited academic medical institution within the United States. For quantitative data, the analytic strategy focused on item-level descriptive analyses. For the qualitative data, analyses focused on a priori themes and emergent subthemes.

RESULTS

Respondents were 414 researchers from 44 academic medical institutions; 64.5% reported that results should always be shared with participants, yet 60.8% of respondents could identify studies in which they had a leadership role where results were not shared. Emergent subthemes from researchers' reasons why results should be shared included participant ownership of findings and benefits of results sharing to science. Reasons for not sharing included concerns related to participants' health literacy and participants' lack of desire for results. Across all respondents who described barriers to results sharing, the majority described logistical barriers.

CONCLUSIONS

Study findings contribute to the literature by documenting researchers' perspectives and experiences about sharing results with research participants, which can inform efforts to improve results sharing. Most respondents indicated that health research results should always be shared with participants, although the extent to which many respondents described barriers to results sharing as well as reported reasons not to share results suggests difficulties with a one-size-fits-all approach to improving results sharing.

A Population-Based Pharmacokinetic Model Approach to Pantoprazole Dosing for Obese Children and Adolescents

BACKGROUND AND AIMS

Pharmacokinetic data for proton pump inhibitors (PPIs), acid-suppression drugs commonly prescribed to children, are lacking for obese children who are at greatest risk for acid-related disease. In a recent multi-center investigation, we demonstrated decreased, total body weight adjusted, apparent clearance (CL/F) of the PPI pantoprazole for obese children compared with their non-obese peers. Subsequently, we developed a population-based pharmacokinetic (PopPK) model to characterize pantoprazole disposition and evaluated appropriate pantoprazole dosing strategies for obese pediatric patients, using simulation.

METHODS

Pharmacokinetic data from the only prospective study of PPIs in obese children (aged 6-17 years; n = 40) included 273 pantoprazole and 256 pantoprazole-sulfone plasma concentrations, after single oral-dose administration, and were used for pantoprazole model development and covariate analysis (NONMEM®). Model evaluation was performed via bootstrapping and predictive checks, and the final model was applied to simulate systemic pantoprazole exposures for common dosing scenarios.

RESULTS

A two-compartment PopPK model, which included CYP2C19 genotype and total body weight, provided the best fit. Resultant, typical, weight-normalized pantoprazole parameter estimates were different than previously reported for children or adults, with significantly reduced pantoprazole CL/F for obese children. Of the dosing scenarios evaluated, the weight-tiered approach, approved by the US Food and Drug Administration, achieved pantoprazole exposures [area under the curve (AUC0-∞)] within ranges previously reported as therapeutic, without over- or under-prediction for obese children.

CONCLUSIONS

Our data argue against empiric dose escalation of PPIs for obese children and support current FDA-approved pediatric weight-tiered dosing for pantoprazole; however, 3- to 5-fold inter-individual variability in pantoprazole AUC0-∞ remained using this dosing approach.

Atypical Pharmacodynamic Properties and Metabolic Profile of the Abused Synthetic Cannabinoid AB-PINACA: Potential Contribution to Pronounced Adverse Effects Relative to Δ9-THC

Recreational use of marijuana is associated with few adverse effects, but abuse of synthetic cannabinoids (SCBs) can result in anxiety, psychosis, chest pain, seizures and death. To potentially explain higher toxicity associated with SCB use, we hypothesized that AB-PINACA, a common second generation SCB, exhibits atypical pharmacodynamic properties at CB1 cannabinoid receptors (CB1Rs) and/or a distinct metabolic profile when compared to Δ⁹-tetrahydrocannabinol (Δ⁹-THC), the principal psychoactive cannabinoid present in marijuana. Liquid chromatography tandem mass spectrometry (LC/MS) identified AB-PINACA and monohydroxy metabolite(s) as primary phase I metabolites (4OH-AB-PINACA and/or 5OH-AB-PINACA) in human urine and serum obtained from forensic samples. In vitro experiments demonstrated that when compared to Δ⁹-THC, AB-PINACA exhibits similar affinity for CB1Rs, but greater efficacy for G-protein activation and higher potency for adenylyl cyclase inhibition. Chronic treatment with AB-PINACA also results in greater desensitization of CB1Rs (e.g., tolerance) than Δ⁹-THC. Importantly, monohydroxy metabolites of AB-PINACA retain affinity and full agonist activity at CB1Rs. Incubation of 4OH-AB-PINACA and 5OH-AB-PINACA with human liver microsomes (HLMs) results in limited glucuronide formation when compared to that of JWH-018-M2, a major monohydroxylated metabolite of the first generation SCB JWH-018. Finally, AB-PINACA and 4OH-AB-PINACA are active in vivo, producing CB1R-mediated hypothermia in mice. Taken collectively, the atypical pharmacodynamic properties of AB-PINACA at CB1Rs relative to Δ⁹-THC (e.g., higher potency/efficacy and greater production of desensitization), coupled with an unusual metabolic profile (e.g., production of metabolically stable active phase I metabolites) may contribute to the pronounced adverse effects observed with abuse of this SCB compared to marijuana.

SIRT1 Controls Acetaminophen Hepatotoxicity by Modulating Inflammation and Oxidative Stress

AIMS

Sirtuin 1 (SIRT1) is a key player in liver physiology and a therapeutic target against hepatic inflammation. We evaluated the role of SIRT1 in the proinflammatory context and oxidative stress during acetaminophen (APAP)-mediated hepatotoxicity.

RESULTS

SIRT1 protein levels decreased in human and mouse livers following APAP overdose. SIRT1-Tg mice maintained higher levels of SIRT1 on APAP injection than wild-type mice and were protected against hepatotoxicity by modulation of antioxidant systems and restrained inflammatory responses, with decreased oxidative stress, proinflammatory cytokine messenger RNA levels, nuclear factor kappa B (NFκB) signaling, and cell death. Mouse hepatocytes stimulated with conditioned medium of APAP-treated macrophages (APAP-CM) showed decreased SIRT1 levels; an effect mimicked by interleukin (IL)1β, an activator of NFκB. This negative modulation was abolished by neutralizing IL1β in APAP-CM or silencing p65-NFκB in hepatocytes. APAP-CM of macrophages from SIRT1-Tg mice failed to downregulate SIRT1 protein levels in hepatocytes. In vivo administration of the NFκB inhibitor BAY 11-7082 preserved SIRT1 levels and protected from APAP-mediated hepatotoxicity.

INNOVATION

Our work evidenced the unique role of SIRT1 in APAP hepatoprotection by targeting oxidative stress and inflammation.

CONCLUSION

SIRT1 protein levels are downregulated by IL1β/NFκB signaling in APAP hepatotoxicity, resulting in inflammation and oxidative stress. Thus, maintenance of SIRT1 during APAP overdose by inhibiting NFκB might be clinically relevant. Rebound Track: This work was rejected during standard peer review and rescued by Rebound Peer Review (Antioxid Redox Signal 16:293-296, 2012) with the following serving as open reviewers: Rafael de Cabo, Joaquim Ros, Kalervo Hiltunen, and Neil Kaplowitz. Antioxid. Redox Signal. 28, 1187-1208.

Hsp72 protects against liver injury via attenuation of hepatocellular death, oxidative stress, and JNK signaling

BACKGROUND & AIMS

Heat shock protein (Hsp) 72 is a molecular chaperone that has broad cytoprotective functions and is upregulated in response to stress. To determine its hepatic functions, we studied its expression in human liver disorders and its biological significance in newly generated transgenic animals.

METHODS

Double transgenic mice overexpressing Hsp72 (gene Hspa1a) under the control of a tissue-specific tetracycline-inducible system (Hsp72-LAP mice) were produced. Acute liver injury was induced by a single injection of acetaminophen (APAP). Feeding with either a methionine choline-deficient (MCD; 8 weeks) or a 3,5-diethoxycarbonyl-1,4-dihydrocollidine-supplemented diet (DDC; 12 weeks) was used to induce lipotoxic injury and Mallory-Denk body (MDB) formation, respectively. Primary hepatocytes were treated with palmitic acid.

RESULTS

Patients with non-alcoholic steatohepatitis and chronic hepatitis C infection displayed elevated HSP72 levels. These levels increased with the extent of hepatic inflammation and HSP72 expression was induced after treatment with either interleukin (IL)-1β or IL-6. Hsp72-LAP mice exhibited robust, hepatocyte-specific Hsp72 overexpression. Primary hepatocytes from these animals were more resistant to isolation-induced stress and Hsp72-LAP mice displayed lower levels of hepatic injury in vivo. Mice overexpressing Hsp72 had fewer APAP protein adducts and were protected from oxidative stress and APAP-/MCD-induced cell death. Hsp72-LAP mice and/or hepatocytes displayed significantly attenuated Jnk activation. Overexpression of Hsp72 did not affect steatosis or the extent of MDB formation.

CONCLUSIONS

Our results demonstrate that HSP72 induction occurs in human liver disease, thus, HSP72 represents an attractive therapeutic target owing to its broad hepatoprotective functions.

LAY SUMMARY

HSP72 constitutes a stress-inducible, protective protein. Our data demonstrate that it is upregulated in patients with chronic hepatitis C and non-alcoholic steatohepatitis. Moreover, Hsp72-overexpressing mice are protected from various forms of liver stress.

Altered metabolism of synthetic cannabinoid JWH-018 by human cytochrome P450 2C9 and variants

Synthetic cannabinoids (SCBs), synonymous with 'K2', 'Spice' or 'synthetic marijuana', are psychoactive drugs of abuse that frequently result in clinical effects and toxicity more severe than those classically associated with Δ⁹-tetrahydrocannabinol such as extreme agitation, hallucinations, supraventricular tachycardia, syncope, and seizures. JWH-018 is one of the earliest compounds identified in various SCB products, and our laboratory previously demonstrated that JWH-018 undergoes extensive metabolism by cytochromes P450 (P450), binds to, and activates cannabinoid receptors (CBRs). The major enzyme involved in the metabolism of JWH-018 is CYP2C9, a highly polymorphic enzyme found largely in the intestines and liver, with *1 being designated as the wild type, and *2 and *3 as the two most common variants. Three different major products have been identified in human urine and plasma: JWH-018 (ω)-OH, JWH-018 (ω-1)-OH(R), and JWH-018 (ω-1)-OH(S). The (ω-1)-OH metabolite of JWH-018 is a chiral molecule, and is thus designated as either (ω-1)-OH(R) or (ω-1)-OH(S). Here, in vitro enzyme kinetic assays performed with human recombinant CYP2C9 variants (*1, *2, and *3) revealed that oxidative metabolism by CYP2C9*3 resulted in significantly less formation of (ω)-OH and (ω-1)-OH metabolites. Surprisingly, CYP2C9*2 was roughly 3.6-fold more efficient as the CYP2C9*1 enzyme based on V_max/K_m, increasing the rate of JWH-018 metabolism and allowed for a much more rapid elimination. These results suggest that genetic polymorphisms of P450 enzymes result in the production of varying levels of biologically active JWH-018 metabolites in some individuals, offering a mechanistic explanation for the diverse clinical toxicity often observed following JWH-018 abuse.

The impact of strength level on adaptations to combined weightlifting, plyometric, and ballistic training

The purpose of this investigation was to determine whether the magnitude of adaptation to integrated ballistic training is influenced by initial strength level. Such information is needed to inform resistance training guidelines for both higher- and lower-level athlete populations. To this end, two groups of distinctly different strength levels (stronger: one-repetition-maximum (1RM) squat = 2.01 ± 0.15 kg·BM^-1 ; weaker: 1.20 ± 0.20 kg·BM^-1 ) completed 10 weeks of resistance training incorporating weightlifting derivatives, plyometric actions, and ballistic exercises. Testing occurred at pre-, mid-, and post-training. Measures included variables derived from the incremental-load jump squat and the 1RM squat, alongside muscle activity (electromyography), and jump mechanics (force-time comparisons throughout the entire movement). The primary outcome variable was peak velocity derived from the unloaded jump squat. It was revealed that the stronger group displayed a greater (P = .05) change in peak velocity at mid-test (baseline: 2.65 ± 0.10 m/s, mid-test: 2.80 ± 0.17 m/s) but not post-test (2.85 ± 0.18 m/s) when compared to the weaker participants (baseline 2.43 ± 0.09, mid-test. 2.47 ± 0.11, post-test: 2.61 ± 0.10 m/s). Different changes occurred between groups in the force-velocity relationship (P = .001-.04) and jump mechanics (P ≤ .05), while only the stronger group displayed increases in muscle activation (P = .05). In conclusion, the magnitude of improvement in peak velocity was significantly influenced by pre-existing strength level in the early stage of training. Changes in the mechanisms underpinning performance were less distinct.

Comparative Analysis of Ampicillin Plasma and Dried Blood Spot Pharmacokinetics in Neonates

BACKGROUND

Dried blood spot (DBS) is a practical sampling strategy for pharmacokinetic studies in neonates. The utility of DBS to determine the population pharmacokinetics (pop-PK) of ampicillin, as well as accuracy versus plasma samples, was evaluated.

METHODS

An open-label, multicenter, opportunistic, prospective study was conducted in neonates. Ampicillin concentrations from plasma and DBS (CONCPlasma and CONCDBS) were measured by liquid chromatographic tandem mass spectrometry and analyzed using pop-PK and statistical (including transformation) approaches.

RESULTS

A total of 29 paired plasma and DBS samples from 18 neonates were analyzed. The median (range) gestational age and postnatal age were 37 (27-41) weeks and 8 (1-26) days, respectively. The geometric mean of CONCDBS to CONCPlasma ratio was 0.56. Correlation analysis demonstrated strong association between CONCPlasma and CONCDBS (r = 0.902, analysis of variance P < 0.001). Using linear regression transformation, the estimated CONCPlasma (eCONCPlasma) was derived using (CONCDBS - 3.223)/0.51. The median bias and geometric mean ratio improved to -11% and 0.88 (Wilcoxon signed-rank test, P < 0.001), respectively, when comparing eCONCPlasma to CONCPlasma. Furthermore, using pop-PK modeling, the median bias (interquartile range) for clearance and individual predicted concentrations improved to 8% (-11 to 50) and -8% (-34 to 11), respectively, when eCONCPlasma was used.

CONCLUSIONS

After transformation, DBS sampling accurately predicted ampicillin exposure in neonates.

Obese Children Require Lower Doses of Pantoprazole Than Nonobese Peers to Achieve Equal Systemic Drug Exposures

OBJECTIVE

To assess appropriate pantoprazole dosing for obese children, we conducted a prospective pharmacokinetics (PK) investigation of pantoprazole in obese children, a patient population that is traditionally excluded from clinical trials.

STUDY DESIGN

A total of 41 obese children (6-17 years of age), genotyped for CYP2C19 variants *2, *3, *4, and *17, received a single oral dose of pantoprazole, ~1.2 mg/kg lean body weight (LBW), with LBW calculated via a validated formula. Ten post-dose pantoprazole plasma concentrations were measured, and PK variables generated via noncompartmental methods (WinNonlin). Linear and nonlinear regression analyses and analyses of variance were used to explore obesity, age, and CYP2C19 genotype contribution to pantoprazole PK. PK variables of interest were compared with historic nonobese peers treated with pantoprazole.

RESULTS

Independent of genotype, when normalized to dose per kg total body weight, pantoprazole apparent clearance and apparent volume of distribution were significantly lower (P < .05) and systemic exposure significantly higher (P < .01) in obese vs nonobese children. When normalized per kg LBW, these differences were not evident in children ≥12 years of age and markedly reduced in children <12 years of age.

CONCLUSIONS

LBW dosing of pantoprazole led to pantoprazole PK similar to nonobese peers. Additional factors, other than body size (eg, age-related changes in CYP2C19 activity), appear to affect pantoprazole PK in children <12 years of age.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02186652.

Peripheral quantitative computed tomography detects differences at the radius in prepubertal children with cystic fibrosis compared to healthy controls

Introduction

In 2015, 11.9% of people with cystic fibrosis (CF) in the United States had osteopenia, 5.1% osteoporosis, and 0.3% experienced a fracture. Screening for CF-related bone disease starts in childhood, and dual energy x-ray absorptiometry (DXA) is the recommended method. It is unknown whether peripheral quantitative computed tomography (pQCT) can detect deficits earlier than DXA. This study compared pQCT and DXA scans in a group of pre-pubertal children with CF and healthy controls.

Methods

This was a cross-sectional study of children at Tanner stage 1. A pQCT scan of the radius at proximal and distal sites was performed plus a total body DXA scan. Serum C-reactive protein, interleukin-6 and tumor necrosis factor-alpha were also measured.

Results

A total of 34 subjects completed the study; 14 with CF and 20 controls. At the distal radius, pQCT showed a lower total bone mineral density (BMD) Z-score for the CF group (P = 0.01 and P = 0.03 for 2 different reference databases) compared to controls. At the proximal site, the polar strength-strain index was lower in the CF group (P = 0.017). Finally, the total body BMD Z-score by DXA was lower in the CF group, although it did not meet the definition of reduced bone density (P = 0.004). Biomarkers of inflammation were not different.

Conclusions

In this group of pre-pubertal children with CF, measures of bone strength and density by both pQCT and DXA were reduced compared to healthy controls.

Metabolomics Analysis of Urine Samples from Children after Acetaminophen Overdose

Acetaminophen (APAP), a commonly used over-the-counter analgesic, accounts for approximately fifty percent of the cases of acute liver failure (ALF) in the United States due to overdose, with over half of those unintentional. Current clinical approaches for assessing APAP overdose rely on identifying the precise time of overdose and quantitating acetaminophen alanine aminotransferase (ALT) levels in peripheral blood. Novel specific and sensitive biomarkers may provide additional information regarding patient status post overdose. Previous non-clinical metabolomics studies identified potential urinary biomarkers of APAP-induced hepatotoxicity and metabolites involved pathways of tricarboxylic acid cycle, ketone metabolism, and tryptophan metabolism. In this study, biomarkers identified in the previous non-clinical study were evaluated in urine samples collected from healthy subjects ( N = 6, median age 14.08 years) and overdose patients ( N = 13, median age 13.91 years) as part of an IRB-approved multicenter study of APAP toxicity in children. The clinical results identified metabolites from pathways previously noted, and pathway analysis indicated analogous pathways were significantly altered in both the rats and humans after APAP overdose. The results suggest a metabolomics approach may enable the discovery of specific, translational biomarkers of drug-induced hepatotoxicity that may aid in the assessment of patients.

Dalbavancin Pharmacokinetics and Safety in Children 3 Months to 11 Years of Age

BACKGROUND

Dalbavancin is a novel lipoglycopeptide antibiotic that has potent in vitro activity against Gram-positive microorganisms.

METHODS

We performed a phase 1, open-label, multicenter study to investigate the pharmacokinetics (PK) and safety of a single dose of intravenous dalbavancin in hospitalized pediatric subjects 3 months to 11 years of age. We combined these data with previously collected adolescent PK data and performed a population PK analysis.

RESULTS

Model development was performed using 311 dalbavancin plasma concentrations from 43 subjects. The median age was 5.9 years (range: 0.3-16.9). A 3-compartment, linear PK model was developed. Based on simulations, the following age-dependent dosing regimen was found to achieve similar dalbavancin exposure to that in adults administered a 2-dose regimen: children 6 to <18 years of age, 12 mg/kg (1000 mg maximum) on day 1 and 6 mg/kg (500 mg maximum) on day 8 and children 3 months to <6 years of age, 15 mg/kg (1000 mg maximum) on day 1 and 7.5 mg/kg (500 mg maximum) on day 8. Similarly, the following age-dependent regimen was found to match adult exposure after a single-dose (1500 mg): 6 to <18 years of age, 18 mg/kg (1500 mg maximum) on day 1 and 3 months to <6 years of age, 22.5 mg/kg (1500 mg maximum) on day 1. Nineteen subjects experienced 36 treatment-emergent adverse events. Five of 36 adverse events were assessed as possibly or probably related to treatment.

CONCLUSIONS

Dalbavancin pediatric dosing that matched adult exposure was identified. Overall, dalbavancin was well tolerated in our study population.

Race, Gender, and Genetic Polymorphism Contribute to Variability in Acetaminophen Pharmacokinetics, Metabolism, and Protein-Adduct Concentrations in Healthy African-American and European-American Volunteers

Over 30 years ago, black Africans from Kenya and Ghana were shown to metabolize acetaminophen faster by glucuronidation and slower by oxidation compared with white Scottish Europeans. The objectives of this study were to determine whether similar differences exist between African-Americans and European-Americans, and to identify genetic polymorphisms that could explain these potential differences. Acetaminophen plasma pharmacokinetics and partial urinary metabolite clearances via glucuronidation, sulfation, and oxidation were determined in healthy African-Americans (18 men, 23 women) and European-Americans (34 men, 20 women) following a 1-g oral dose. There were no differences in acetaminophen total plasma, glucuronidation, or sulfation clearance values between African-Americans and European-Americans. However, median oxidation clearance was 37% lower in African-Americans versus European-Americans (0.57 versus 0.90 ml/min per kilogram; P = 0.0001). Although acetaminophen total or metabolite clearance values were not different between genders, shorter plasma half-life values (by 11-14%; P < 0.01) were observed for acetaminophen, acetaminophen glucuronide, and acetaminophen sulfate in women versus men. The UGT2B15*2 polymorphism was associated with variant-allele-number proportional reductions in acetaminophen total clearance (by 15-27%; P < 0.001) and glucuronidation partial clearance (by 23-48%; P < 0.001). UGT2B15 *2/*2 genotype subjects also showed higher acetaminophen protein-adduct concentrations than *1/*2 (by 42%; P = 0.003) and *1/*1 (by 41%; P = 0.003) individuals. Finally, CYP2E1 *1D/*1D genotype African-Americans had lower oxidation clearance than *1C/*1D (by 42%; P = 0.041) and *1C/*1C (by 44%; P = 0.048) African-Americans. Consequently, African-Americans oxidize acetaminophen more slowly than European-Americans, which may be partially explained by the CYP2E1*1D polymorphism. UGT2B15*2 influences acetaminophen pharmacokinetics in both African-Americans and European-Americans.

Targeted metabolomic profiling indicates structure-based perturbations in serum phospholipids in children with acetaminophen overdose

Phospholipids are an important class of lipids that act as building blocks of biological cell membranes and participate in a variety of vital cellular functions including cell signaling. Previous studies have reported alterations in phosphatidylcholine (PC) and lysophosphatidylcholine (lysoPC) metabolism in acetaminophen (APAP)-treated animals or cell cultures. However, little is known about phospholipid perturbations in humans with APAP toxicity. In the current study, targeted metabolomic analysis of 180 different metabolites including 14 lysoPCs and 73 PCs was performed in serum samples from children and adolescents hospitalized for APAP overdose. Metabolite profiles in the overdose group were compared to those of healthy controls and hospitalized children receiving low dose APAP for treatment of pain or fever (therapeutic group). PCs and lysoPCs with very long chain fatty acids (VLCFAs) were significantly decreased in the overdose group, while those with comparatively shorter chain lengths were increased in the overdose group compared to the therapeutic and control groups. All ether linked PCs were decreased in the overdose group compared to the controls. LysoPC-C26:1 was highly reduced in the overdose group and could discriminate between the overdose and control groups with 100% sensitivity and specificity. The PCs and lysoPCs with VLCFAs showed significant associations with changes in clinical indicators of drug metabolism (APAP protein adducts) and liver injury (alanine aminotransferase, or ALT). Thus, a structure-dependent reduction in PCs and lysoPCs was observed in the APAP-overdose group, which may suggest a structure-activity relationship in inhibition of enzymes involved in phospholipid metabolism in APAP toxicity.

Salivary caffeine concentrations are comparable to plasma concentrations in preterm infants receiving extended caffeine therapy

AIMS

Caffeine concentrations in preterm infants are usually measured in the blood. However, salivary assays may provide a valid and practical alternative. The present study explored the validity and clinical utility of salivary caffeine concentrations as an alternative to blood concentrations and developed a novel plasma/salivary caffeine distribution model.

METHODS

Paired salivary and plasma samples were obtained in 29 infants. Salivary samples were obtained using a commercially available salivary collection system. Caffeine concentrations in the saliva and plasma were determined using high-performance liquid chromatography. A population pharmacokinetic (PK) model was developed using NONMEM 7.3.

RESULTS

The mean (± standard deviation) gestational age (GA) at birth and birth weight were 27.9 ± 2.1 weeks and 1171.6 ± 384.9 g, respectively. Paired samples were obtained at a mean postmenstrual age (PMA) of 35.5 ± 1.1 weeks. The range of plasma caffeine concentrations was 9.5-54.1 μg ml(-1) , with a mean difference (95% confidence interval) between plasma and salivary concentrations of -0.18 μg ml(-1) (-1.90, 1.54). Salivary and plasma caffeine concentrations were strongly correlated (Pearson's correlation coefficient = 0.87, P < 0.001). Caffeine PK in plasma and saliva was simultaneously described by a three-compartment recirculation model. Current body weight, birth weight, GA, PMA and postnatal age were not significantly correlated with any PK parameter.

CONCLUSIONS

Salivary sampling provides an easy, non-invasive method for measuring caffeine concentrations. Salivary concentrations correlate highly with plasma concentrations. Caffeine PK in saliva and plasma are well described by a three-compartment recirculation model.

Retinoid regulation of antiviral innate immunity in hepatocytes

Persistent infection of hepatitis C virus (HCV) is one of the leading causes of end-stage liver disease (ESLD), such as decompensated cirrhosis and liver cancer. Of particular note, nearly half of HCV-infected people in the United States are reported to be heavy drinkers. This particular group of patients is known to rapidly progress to the ESLD. Although accelerated disease progression among alcohol abusers infected with HCV is clinically well recognized, the molecular pathophysiology behind this manifestation has not been well elucidated. Hepatocytes metabolize ethanol (EtOH) primarily through two steps of oxidative catabolism in which alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) play central roles. The ADH-ALDH pathway also governs the metabolism of retinol (vitamin A) to its transcriptionally active metabolite, retinoic acid (RA). In this study, we defined that the ADH-ALDH pathway serves as a potent antiviral host factor in hepatocytes, which regulates the expression of interferon (IFN)-stimulated genes (ISGs) by biogenesis of RA. ISGs constitute over 300 antiviral effectors, which cooperatively govern intracellular antiviral innate immunity. Our study revealed that intracellular RA levels greatly influence ISG expression under basal conditions. Moreover, RA augments ISG induction in response to viral infection or exposure to IFN in a gene-specific manner. Lastly, our results demonstrated that EtOH attenuates the antiviral function of the ADH-ALDH pathway, which suggests the possibility that EtOH-retinol metabolic competition is one of the molecular mechanisms for the synergism between HCV and alcohol abuse in liver disease progression.

CONCLUSIONS

RA plays a critical role in the regulation of intracellular antiviral innate immunity in hepatocytes. (Hepatology 2016;63:1783-1795).

Solithromycin Pharmacokinetics in Plasma and Dried Blood Spots and Safety in Adolescents

We assessed the pharmacokinetics and safety of solithromycin, a fluoroketolide antibiotic, in a phase 1, open-label, multicenter study of 13 adolescents with suspected or confirmed bacterial infections. On days 3 to 5, the mean (standard deviation) maximum plasma concentration and area under the concentration versus time curve from 0 to 24 h were 0.74 μg/ml (0.61 μg/ml) and 9.28 μg · h/ml (6.30 μg · h/ml), respectively. The exposure and safety in this small cohort of adolescents were comparable to those for adults. (This study has been registered at ClinicalTrials.gov under registration no. NCT01966055.).

The neuronal nitric oxide synthase inhibitor NANT blocks acetaminophen toxicity and protein nitration in freshly isolated hepatocytes

3-Nitrotyrosine (3NT) in liver proteins of mice treated with hepatotoxic doses of acetaminophen (APAP) has been postulated to be causative in toxicity. Nitration is by a reactive nitrogen species formed from nitric oxide (NO). The source of the NO is unclear. iNOS knockout mice were previously found to be equally susceptible to APAP toxicity as wildtype mice and iNOS inhibitors did not decrease toxicity in mice or in hepatocytes. In this work we examined the potential role of nNOS in APAP toxicity in hepatocytes using the specific nNOS inhibitor NANT (10 µM)(N-[(4S)-4-amino-5-[(2-aminoethyl)amino]pentyl]-N'-nitroguanidinetris (trifluoroacetate)). Primary hepatocytes (1 million/ml) from male B6C3F1 mice were incubated with APAP (1mM). Cells were removed and assayed spectrofluorometrically for reactive nitrogen and oxygen species using diaminofluorescein (DAF) and Mitosox red, respectively. Cytotoxicity was determined by LDH release into media. Glutathione (GSH, GSSG), 3NT, GSNO, acetaminophen-cysteine adducts, NAD, and NADH were measured by HPLC. APAP significantly increased cytotoxicity at 1.5-3.0 h. The increase was blocked by NANT. NANT did not alter APAP mediated GSH depletion or acetaminophen-cysteine adducts in proteins which indicated that NANT did not inhibit metabolism. APAP significantly increased spectroflurometric evidence of reactive nitrogen and oxygen formation at 0.5 and 1.0 h, respectively, and increased 3NT and GSNO at 1.5-3.0 h. These increases were blocked by NANT. APAP dramatically increased NADH from 0.5-3.0 h and this increase was blocked by NANT. Also, APAP decreased the Oxygen Consumption Rate (OCR), decreased ATP production, and caused a loss of mitochondrial membrane potential, which were all blocked by NANT.

Accuracy of the Spacelabs 90217 ambulatory blood pressure monitor in a pediatric population

BACKGROUND

Ambulatory blood pressure monitoring techniques provide unique advantages for diagnosing hypertension, although few devices have been independently validated in the pediatric population.

METHODS

We sought to validate the accuracy of ambulatory blood pressure monitoring with the Spacelabs 90217 monitor in children using a modified British Hypertension Society protocol.

RESULTS

A total of 112 children, aged between 6 and 17 years, completed the study at one of the three participating centers. Overall, the monitor earned an 'A' for systolic blood pressure and 'B' for diastolic blood pressure. It performed slightly better among 6-12 year olds (A/A) compared with 13-17 year olds (A/B).

CONCLUSIONS

We conclude that the Spacelabs 90217 monitor is an appropriate monitor for use in children who are 6 years of age or older.

Translational biomarkers of acetaminophen-induced acute liver injury

Acetaminophen (APAP) is a commonly used analgesic drug that can cause liver injury, liver necrosis and liver failure. APAP-induced liver injury is associated with glutathione depletion, the formation of APAP protein adducts, the generation of reactive oxygen and nitrogen species and mitochondrial injury. The systems biology omics technologies (transcriptomics, proteomics and metabolomics) have been used to discover potential translational biomarkers of liver injury. The following review provides a summary of the systems biology discovery process, analytical validation of biomarkers and translation of omics biomarkers from the nonclinical to clinical setting in APAP-induced liver injury.

Human keratin 8 variants promote mouse acetaminophen hepatotoxicity coupled with c-jun amino-terminal kinase activation and protein adduct formation

Keratins 8 and 18 (K8/K18) are the intermediate filaments proteins of simple-type digestive epithelia and provide important cytoprotective function. K8/K18 variants predispose humans to chronic liver disease progression and poor outcomes in acute acetaminophen (APAP)-related liver failure. Given that K8 G62C and R341H/R341C are common K8 variants in European and North American populations, we studied their biological significance using transgenic mice. Mice that overexpress the human K8 variants, R341H or R341C, were generated and used together with previously described mice that overexpress wild-type K8 or K8 G62C. Mice were injected with 600 mg/kg of APAP or underwent bile duct ligation (BDL). Livers were evaluated by microarray analysis, quantitative real-time polymerase chain reaction, immunoblotting, histological and immunological staining, and biochemical assays. Under basal conditions, the K8 G62C/R341H/R341C variant-expressing mice did not show an obvious liver phenotype or altered keratin filament distribution, whereas K8 G62C/R341C animals had aberrant disulphide cross-linked keratins. Animals carrying the K8 variants displayed limited gene expression changes, but had lower nicotinamide N-methyl transferase (NNMT) levels and were predisposed to APAP-induced hepatotoxicity. NNMT represents a novel K8/K18-associated protein that becomes up-regulated after K8/K18 transfection. The more pronounced liver damage was accompanied by increased and prolonged JNK activation; elevated APAP protein adducts; K8 hyperphosphorylation at S74/S432 with enhanced keratin solubility; and prominent pericentral keratin network disruption. No differences in APAP serum levels, glutathione, or adenosine triphosphate levels were noted. BDL resulted in similar liver injury and biliary fibrosis in all mouse genotypes.

CONCLUSION

Expression of human K8 variants G62C, R341H, or R341C in mice predisposes to acute APAP hepatotoxicity, thereby providing direct evidence for the importance of these variants in human acute liver failure.

Cooperativity in CYP2E1 metabolism of acetaminophen and styrene mixtures

Risk assessment for exposure to mixtures of drugs and pollutants relies heavily on in vitro characterization of their bioactivation and/or metabolism individually and extrapolation to mixtures assuming no interaction. Herein, we demonstrated that in vitro CYP2E1 metabolic activation of acetaminophen and styrene mixtures could not be explained through the Michaelis-Menten mechanism or any models relying on that premise. As a baseline for mixture studies with styrene, steady-state analysis of acetaminophen oxidation revealed a biphasic kinetic profile that was best described by negative cooperativity (Hill coefficient=0.72). The best-fit mechanism for this relationship involved two binding sites with differing affinities (Ks=830μM and Kss=32mM). Introduction of styrene inhibited that reaction less than predicted by simple competition and thus provided evidence for a cooperative mechanism within the mixture. Likewise, acetaminophen acted through a mixed-type inhibition mechanism to impact styrene epoxidation. In this case, acetaminophen competed with styrene for CYP2E1 (Ki=830μM and Ksi=180μM for catalytic and effector sites, respectively) and resulted in cooperative impacts on binding and catalysis. Based on modeling of in vivo clearance, cooperative interactions between acetaminophen and styrene resulted in profoundly increased styrene activation at low styrene exposure levels and therapeutic acetaminophen levels. Current Michaelis-Menten based toxicological models for mixtures such as styrene and acetaminophen would fail to detect this concentration-dependent relationship. Hence, future studies must assess the role of alternate CYP2E1 mechanisms in bioactivation of compounds to improve the accuracy of interpretations and predictions of toxicity.