Design and synthesis of aminopyridine containing biaryls reducing c-MYC protein levels in cells

The c-MYC oncogene transcription factor has been implicated in cell cycle regulation controlling cell growth and proliferation. It is tightly regulated in normal cells, but has been shown to be deregulated in cancer cells, and is thus an attractive target for oncogenic therapies. Building upon previous SAR, a series of analogues containing benzimidazole core replacements were prepared and evaluated, leading to the identification of imidazopyridazine compounds that were shown to possess equivalent or improved c-MYC HTRF pEC50 values, lipophilicity, solubility, and rat pharmacokinetics. The imidazopyridazine core was therefore determined to be superior to the original benzimidazole core and a viable alternate for continued lead optimization and medicinal chemistry campaigns.

Safe Management by a Pop-Up Eating Disorder Team

Background Anorexia nervosa has a high mortality complicated by risks of under-nourishment, over-nourishment and care can be compromised by behavioural issues. Methods This is a retrospective study of ten patients with eating disorders admitted to Sligo University Hospital, treated by a "pop-up"/on demand multidisciplinary eating disorder team. Results All were female, mean BMI on admission was 14.35kg/m2, on discharge was 16.59kg/m2, (p=0.001) and was significantly lower than the initial measurement and may represent water-loading or bowel retention. Admission biochemistry was normal in nine subjects. Six subjects experienced refeeding syndrome, one was hypoglycaemic (3.1mmol/L) in the setting of an aspiration pneumonia, and five exhibited treatment avoiding behaviour including food caching, micro exercising. The mean length of stay was 38 days and was positively correlated with weight gain during admission (p=0.02). 6-month follow up BMI was higher than admission in eight subjects and the other two voluntarily withdrew from follow-up. Conclusion There was a high incidence of treatment avoiding behaviour, initial weights were misleadingly high, admission biochemistry misleadingly normal, hypoglycaemia associated with infection, and incidence of refeeding syndrome is high. Notwithstanding this these patients can be managed safely and effectively in a general hospital with a coordinated, well-structured approach by a multidisciplinary team.

Cell-Based Drug Discovery: Identification and Optimization of Small Molecules that Reduce c-MYC Protein Levels in Cells

Elevated expression of the c-MYC oncogene is one of the most common abnormalities in human cancers. Unfortunately, efforts to identify pharmacological inhibitors that directly target MYC have not yet yielded a drug-like molecule due to the lack of any known small molecule binding pocket in the protein, which could be exploited to disrupt MYC function. We have recently described a strategy to target MYC indirectly, where a screening effort designed to identify compounds that can rapidly decrease endogenous c-MYC protein levels in a MYC-amplified cell line led to the discovery of a compound series that phenocopies c-MYC knockdown by siRNA. Herein, we describe our medicinal chemistry program that led to the discovery of potent, orally bioavailable c-MYC-reducing compounds. The development of a minimum pharmacophore model based on empirical structure activity relationship as well as the property-based approach used to modulate pharmacokinetics properties will be highlighted.

Diabetes care and pregnancy outcomes for women with pregestational diabetes in Ireland

AIMS

Pre-gestational diabetes mellitus (PGDM) is associated with adverse outcomes. We aimed to examine pregnancies affected by PGDM; report on these pregnancy outcomes and compare outcomes for patients with type 1 versus type 2 diabetes mellitus; compare our findings to published Irish and United Kingdom (UK) data and identify potential areas for improvement.

METHODS

Between 2016 and 2018 information on 679 pregnancies from 415 women with type 1 Diabetes Mellitus and 244 women with type 2 diabetes was analysed. Data was collected on maternal characteristics; pregnancy preparation; glycaemic control; pregnancy related complications; foetal and maternal outcomes; unscheduled hospitalisations; congenital anomalies and perinatal deaths.

RESULTS

Only 15.9% of women were adequately prepared for pregnancy. Significant deficits were identified in availability and attendance at pre-pregnancy clinic, use of folic acid, attaining appropriate glycaemic targets and appropriate retinal screening. The majority of pregnancies (n = 567, 83.5%) resulted in a live birth but the large number of infants born large for gestational age (LGA) (n = 280, 49.4%), born prematurely <37 weeks and requiring neonatal intensive care unit (NICU) admission continue to be significant issues.

CONCLUSIONS

This retrospective cohort study identifies multiple targets for improvements in the provision of care to women with pre-gestational DM which are likely to translate into better pregnancy outcomes.

An Irish National Diabetes in Pregnancy Audit: aiming for best outcomes for women with diabetes

AIMS

The purpose of this study was to identify the number of pregnancies affected by pre-gestational diabetes in the Republic of Ireland; to report on pregnancy outcomes and to identify areas for improvement in care delivery and clinical outcomes.

METHODS

Healthcare professionals caring for women with pre-gestational diabetes during pregnancy were invited to participate in this retrospective study. Data pertaining to 185 pregnancies in women attending 15 antenatal centres nationally were collected and analysed. Included pregnancies had an estimated date of delivery between 1 January and 31 December 2015.

RESULTS

The cohort consisted of 122 (65.9%) women with Type 1 diabetes and 56 (30.3%) women with Type 2 diabetes. The remaining 7 (3.8%) pregnancies were to women with maturity-onset diabetes of the young (MODY) (n = 6) and post-transplant diabetes (n = 1). Overall women were poorly prepared for pregnancy and lapses in specific areas of service delivery including pre-pregnancy care and retinal screening were identified. The majority of pregnancies 156 (84.3%) resulted in a live birth. A total of 103 (65.5%) women had a caesarean delivery and 58 (36.9%) infants were large for gestational age.

CONCLUSIONS

This audit identifies clear areas for improvement in delivery of care for women with diabetes in the Republic of Ireland before and during pregnancy.

The impact of the World Health Organization Health Promoting Schools framework approach on diet and physical activity behaviours of adolescents in secondary schools: a systematic review

OBJECTIVE

To examine the effectiveness of interventions using the World Health Organization Health Promoting Schools (HPSs) framework approach in increasing physical activity (PA) and improving the diet of 11-18-year-olds.

STUDY DESIGN

A systematic review guided by the National Health Services Centre for Reviews and Dissemination framework and reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses.

METHODS

Nine databases and trial registries were searched from 2013 to 2018 for cluster randomised controlled trials involving adolescents' aged 11-18 years. We also included relevant studies from a 2014 Cochrane Review of HPS approach on health behaviours. Data were extracted from included studies and assessed for quality.

RESULTS

Twelve eligible studies were identified from seven countries. The studies varied in outcome measures, sample size, quality and duration of intervention and follow-up. Only four of the included studies were of high to moderate quality. We found some evidence of effectiveness for physical activity only interventions and limited evidence of effectiveness for nutrition only and combined PA and nutrition interventions.

CONCLUSIONS

There were no discernible patterns across the studies to suggest effective mechanisms for the HPS approach. The family/community component was poorly developed and superficially reported in all studies. Future research should seek to understand how best to work in partnership with secondary schools, to foster and sustain a healthy eating and physical activity culture, which aligns with their core aims. More attention should be paid to the restriction of unhealthy foods in the school environment.

Discovery of Isoxazole Amides as Potent and Selective SMYD3 Inhibitors

We report herein the discovery of isoxazole amides as potent and selective SET and MYND Domain-Containing Protein 3 (SMYD3) inhibitors. Elucidation of the structure-activity relationship of the high-throughput screening (HTS) lead compound 1 provided potent and selective SMYD3 inhibitors. The SAR optimization, cocrystal structures of small molecules with SMYD3, and mode of inhibition (MOI) characterization of compounds are described. The synthesis and biological and pharmacokinetic profiles of compounds are also presented.

The impact of active stakeholder involvement on recruitment, retention and engagement of schools, children and their families in the cluster randomised controlled trial of the Healthy Lifestyles Programme (HeLP): a school-based intervention to prevent obesity

Background

Recruitment and retention of participants is crucial for statistical power and internal and external validity and participant engagement is essential for behaviour change. However, many school-based interventions focus on programme content rather than the building of supportive relationships with all participants and tend to employ specific standalone strategies, such as incentives, to improve retention. We believe that actively involving stakeholders in both intervention and trial design improves recruitment and retention and increases the chances of creating an effective intervention.

Methods

The Healthy Lifestyles Programme, HeLP (an obesity prevention programme for children 9–10 years old) was developed using intervention mapping and involved extensive stakeholder involvement in both the design of the trial and the intervention to ensure that: (i) delivery methods were suitably engaging, (ii) deliverers had the necessary skills and qualities to build relationships and (iii) the intervention dovetailed with the National Curriculum. HeLP was a year-long intervention consisting of 4 multi-component phases using a range of delivery methods. We recruited 1324 children from 32 schools from the South West of England to a cluster-randomised controlled trial to determine the effectiveness of HeLP in preventing obesity. The primary outcome was change in body mass index standard deviation score (BMI SDS) at 24 months post randomisation. Secondary outcomes included additional anthropometric and behavioural (physical activity and diet) measures at 18 and 24 months.

Results

Anthropometric and behavioural measures were taken in 99%, 96% and 94% of children at baseline, 18 and 24 months, respectively, with no differential follow up between the control and intervention groups at each time point. All children participated in the programme and 92% of children and 77% of parents across the socio-economic spectrum were considered to have actively engaged with HeLP.

Conclusions

We attribute our excellent retention and engagement results to the high level of stakeholder involvement in both trial and intervention design, the building of relationships using appropriate personnel and creative delivery methods that are accessible to children and their families across the social spectrum.

Trial registration

International Standard Randomised Controlled Trials Register, ISRCTN15811706. Registered on 1 May 2012.

Abstract LB-248: Protein arginine methyltransferase 5 (PRMT5) inhibition as a therapeutic strategy in B-cell lymphoma

PRMT5 is responsible for symmetric dimethylation of arginine residues in glycine and arginine rich (GAR) motifs on a variety of cytosolic and nuclear proteins including histones, spliceosome components, regulators of translation, transcription factors, kinases and others. PRMT5 driven methylation of some of these proteins has been implicated in tumorigenesis. For example, PRMT5 deposits repressive marks on histones and silences a subset of tumor suppressor genes, such as RB and ST7. PRMT5 methylation of non-histone substrates (such as E2F1 and p53) also contributes to cancer cell growth and death. PRMT5 driven methylation of spliceosome subunits and components of translational machinery has been well described but its connection to PRMT5's role in cancer has not been established. We have identified first-in-class small molecules that are highly potent, selective, reversible inhibitors of PRMT5. Cellular mechanistic studies revealed that PRMT5 inhibition decreases symmetric arginine dimethylation on a variety of cellular proteins including spliceosome components, histones and transcription factors. PRMT5 inhibition leads to gene expression and splicing changes ultimately resulting in the induction of p53 in lymphoma cell lines. In addition to impacting the p53 pathway, PRMT5 inhibition leads to attenuation of the expression of cell cycle related genes, genes involved in ribosome and spliceosome homeostasis, as well as genes important for cellular metabolism. PRMT5 inhibitor attenuates proliferation and induces cell death in a subset of mantle cell and diffuse large B-cell lymphoma cell lines and inhibits tumor growth in xenograft models of mantle cell lymphoma. These data underline the potential of PRMT5 inhibitors as a therapeutic strategy in mantle cell and diffuse large B-cell lymphoma.

Citation Format: Olena Barbash, Sarah Gerhart, David Soong, Christine Thompson, Rocio Montes de Oca, Ping Zhang, Charles McHugh, Kristy Kuplast, Christina Majer, Richard Chesworth, Jesse Smith, Robert Copeland, Elayne Penebre, Kenneth Duncan, Neil Johnson, Chris Carpenter, Ryan Kruger. Protein arginine methyltransferase 5 (PRMT5) inhibition as a therapeutic strategy in B-cell lymphoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-248. doi:10.1158/1538-7445.AM2015-LB-248

Abstract 5379: A potent EZH2 inhibitor exhibits long residence time and anti-tumor activity

The EZH2 histone methyltransferase is frequently mutated in diffuse large B-cell lymphoma leading to increased trimethylation of histone H3 lysine 27 (H3K27me3). Drug discovery efforts have previously identified a pyridone-based chemical series of EZH2 inhibitors that potently and selectively inhibit EZH2 catalytic activity. These compounds are capable of globally decreasing H3K27me3 levels, de-repressing EZH2 target genes, and inducing growth inhibition of many lymphoma cell lines both in cell culture and in vivo. Through medicinal chemistry optimization, we have developed EZH2 inhibitors with significantly improved potency in both biochemical and cellular assays. These compounds exhibit a prolonged enzyme residence time that can be further extended in vitro through the addition of an H3K27me3 peptide. Herein, we report the biochemical and cellular activity of these new EZH2 inhibitors.

Citation Format: Heidi Ott, Glenn van Aller, Jessica Ward, BaoChau Le, Cynthia Rominger, James Foley, Susan Korenchuk, Charles McHugh, Michael Butticello, Charles Blackledge, James Brackley, Joelle Burgess, Celine Duquenne, Neil Johnson, Jiri Kasparec, Louis LaFrance, Mei Li, Kenneth McNulty, Kenneth Newlander, Stuart Romeril, Stanley Schmidt, Mark Schulz, Dai-Shi Su, Dominic Suarez, Xinrong Tian, Christopher Carpenter, Juan Luengo, Ryan Kruger, Steven Knight, Michael T. McCabe. A potent EZH2 inhibitor exhibits long residence time and anti-tumor activity. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5379. doi:10.1158/1538-7445.AM2015-5379

Abstract 3514: A novel inhibitor of IDH1 abrogates 2-HG production and reverses aberrant epigenetic alterations in IDH1 mutant cells

The isocitrate dehydrogenase 1 (IDH1) and IDH2 genes are mutated in acute myelogenous leukemia, low-grade glioma, intrahepatic cholangiocarcinoma, and chondrosarcomas. IDH1 and IDH2 normally function to convert isocitrate into alpha-ketoglutarate. However, when these enzymes are mutated at select residues the mutant enzymes now convert α-KG into 2-hydroxyglutarate (2-HG). In normal cells, 2-HG levels are typically extremely low, but IDH1/2 mutant cells can accumulate up to 10 mM 2-HG. In an effort to counteract the neomorphic activity of mutant IDH enzymes, we identified and developed potent inhibitors of IDH1. The compounds inhibit IDH1 catalytic activity in biochemical assays and reduce 2-HG production in IDH1-mutant cell lines. Consistent with the fact that 2-HG inhibits α-KG dependent enzymes including histone demethylases and Tet family hydroxylases, these IDH1 inhibitors induce a decrease in several histone methylation marks and also DNA methylation. These data demonstrate that small molecule inhibitors can reverse many of the epigenetic effects of mutant IDH1.

Note: This abstract was not presented at the meeting.

Citation Format: Cynthia Rominger, Chad Quinn, Enoch Gao, Beth Pietrak, Alan Rendina, Angela Smallwood, Arthur Groy, Susan Korenchuk, Charles McHugh, Ken Wiggall, Alexander Reif, Stanley Schmidt, Hongwei Qi, Huizhen Zhao, Nestor Concha, Christopher Carpenter, Juan Luengo, Ryan Kruger, Benjamin Schwartz, Nicholas Adams, Michael T. McCabe. A novel inhibitor of IDH1 abrogates 2-HG production and reverses aberrant epigenetic alterations in IDH1 mutant cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3514. doi:10.1158/1538-7445.AM2015-3514

A comparison of two nasal continuous positive airway pressure interfaces--a randomized crossover study

BACKGROUND

In spite of widespread use of nasal CPAP there are comparatively few studies to guide the choice of nasal prongs.

OBJECTIVES

To determine whether the Fisher & Paykel Healthcare (FPH) neonatal continuous positive airway pressure (CPAP) interface was effective in providing bubble CPAP when compared to the Hudson prong interface.

METHODS

The study was a randomized cross-over study of twenty newborn infants 500 g or more requiring CPAP for respiratory support at birth. Infants were randomized to either the Fisher & Paykel Healthcare or Hudson CPAP interface for twenty four hours. Crossover between interfaces occurred after subsequent twenty four hour periods. The primary outcome was the provision of desired CPAP pressures, defined as provision of CPAP within ± one cm H2O of set pressure.

RESULTS

The percentage time CPAP was within ± one cm H2O of set pressure was 66.5% for the Hudson and 71.8% for the FPH interface (p = 0.66). Oxygen saturations for the Hudson interface were in target range for a median of 97.8% of the time, and, with the FPH interface, for a median of 98.2% of the time (p = 0.76). Clinically significant differences in primary or secondary outcomes between the two groups were not detected.

CONCLUSIONS

The nasal CPAP interfaces studied were equally effective in achieving desired bubble CPAP pressures and target saturations.

Training mental health promotion workers in programme evaluation

In this paper, a programme to train mental health promotion workers in programme evaluation is described and evaluated. The programme is based on adult learning values, guidelines for programme evaluation training and the general principles of mental health promotion. Facilitated over 2 days, the programme also provided individual mentoring. Training was evaluated via a questionnaire immediately before and post training, and 6 months post training (n = 28, n = 18, n = 18). Additionally, individual interviews were used with seven participants and qualitatively analysed. Results indicate significant and sustained positive changes in knowledge, confidence and behaviour and while satisfaction reduced significantly at the six month follow-up, participants' level of satisfaction towards mentoring was consistent. Post training, participants reported a greater appreciation of the importance of evaluation planning and working collaboratively.

Autoimmune encephalitis: a case series and comprehensive review of the literature

Encephalitic syndromes are a common medical emergency. The importance of early diagnosis and appropriate treatment is paramount. If initial investigations for infectious agents prove negative, other diagnoses must be considered promptly. Autoimmune encephalitides are being increasingly recognized as important (and potentially reversible) non-infectious causes of an encephalitic syndrome. We describe four patients with autoimmune encephalitis--3 auto-antibody positive, 1 auto-antibody negative--treated during the last 18 months. A comprehensive review of the literature in this expanding area will be of interest to the infectious diseases, general medical and neurology community.

MER-101–03, a multicenter, phase II study to compare MER-101 20mg tablets to intravenous zoledronic acid 4mg in prostate cancer patients

5161

Background: The primary objective of this study is to examine the pharmacodynamic effects of two different regimens of zoledronic acid, Orazol 20 mg tablets versus Zometa 4mg IV infusion once-monthly therapy on biomarkers in male bisphosphonate-naïve hormone-refractory prostate cancer patients. Methods: The study is an open-label, multi-center phase II clinical trial to compare oral Orazol 20 mg tablets weekly, to infusions of intravenous Zometa 4mg monthly, in males with hormone-refractory prostate cancer, bone metastases, and no prior bisphosphonate treatment. Patients were assigned into one of three cohorts. The three treatments administered were IV Zometa, 4 mg, 15 minute infusion, Day 0 and Day 28; Orazol po, 20 mg, Days 0, 7, 14, 21, 28, 35, 42, and 49; and Orazol po, 20 mg, Days 0, 1, 2, 3, 28, 35, 42, and 49. The study population consisted of men with hormone refractory prostate cancer as evidenced by history of rising PSA levels (last 2 of 3 PSA levels must be above nadir), who are bisphosphonate-naive, and have radiographically-confirmed bone metastases. Efficacy assessments: The primary endpoints are the assessment of response of four biomarkers, urinary NTX, serum CTX, serum bone specific alkaline phosphatase, and serum calcium on days -7, 0, 7, 14, 21, 28, 35, 42, 49, and 56. Secondary endpoints are assessments of performance and pain scores based on ECOG performance status, BPI, and analgesic use. Safety assessments include physical examinations, vital signs and body weight, hematology panel, urinalysis, and blood chemistry panel. Results: The results demonstrated a rapid decrease for all four biomarkers. This decrease was seen at seven days, and was sustained throughout the study. There were no statistically significant differences between any of the treatments in the primary and secondary endpoints. Conclusions: From the results of MER-101–03, Orazol weekly therapy appears to be as effective as Zometa, based on the biomarkers analyzed. Orazol offers a substantial improvement in therapy over IV infusion for patients, with efficacy that is at least comparable based on the results obtained here.

No significant financial relationships to disclose.

Type 2 diabetes mellitus in Navajo adolescents

Diabetes mellitus afflicts over one-fifth of the Navajo population aged over 20 years, but the prevalence of diabetes in Navajo adolescents is unclear. We conducted voluntary testing for diabetes mellitus at two high schools on the Navajo reservation to clarify the prevalence as well as to assess the utility of a high-school based screening program. Body mass index measurements (BMI), oral glucose tolerance tests, and hemoglobin A1C measurements were obtained in consenting high school students. Of the 276 students that participated, 234 were Navajo. Only one Navajo student (0.4%) had diabetes mellitus, although eight (3%) had impaired glucose tolerance or impaired fasting glucose. Participant BMI did not differ significantly from nonparticipant BMI. No correlation existed between BMI or impaired glucose handling, and significant overlap existed between the hemoglobin A1C values of students with impaired glucose handling and students without impaired glucose handling. Increased participation in screening programs may reveal higher disease prevalence, but high school-based screening is not justified by this study, despite the high rates of diabetes mellitus in the Navajo population.

Describing traumatic responses and distress of community residents directly and indirectly exposed to an aircraft crash

This study described the traumatic responses and the extent of psychological distress among residents who had been exposed directly or indirectly to an aircraft crash in Coventry, U.K. The direct exposure group consisted of 62 residents who were on the housing estate at the time of the accident and 20 who were not. They were interviewed on their subjective responses to the crash and then asked to fill in two distress measures: the Impact of Event Scale (IES) and the General Health Questionnaire (GHQ). The results showed a contrast between the responses of the two groups at the time of the crash. They also showed that the direct exposure group had a significantly higher score in the IES item of avoidance, the IES total, the GHQ items of somatization, social dysfunction, and the total score than the indirect exposure group had. Associations were then made between subjective responses and distress measures. Stepwise multiple regression analyses showed that for the direct exposure residents, the IES total was predicted by "whether they received professional help" and "whether they were worried about their safety after the crash." The GHQ total of the direct exposure residents was predicted by "anger about what had happened to them." For the indirect exposure residents, the IES total was predicted by "their present feelings when they heard planes flying over." There were no predictions found between responses and the GHQ total.

Determination of Pranlukast and its metabolites in human plasma by LC/MS/MS with PROSPEKT on-line solid-phase extraction

A highly sensitive and selective liquid chromatography/ionspray tandem mass spectrometry (LC/MS/MS) method was developed and validated for the determination of Pranlukast and its oxidative metabolites (SB 240103, SB 241484 and SB 218663) in human plasma in order to support pharmacokinetic studies. The method employed direct injection of human plasma into an on-line solid phase extraction (SPE) PROSPEKT instrument for isolation of the analytes followed by column switching to the LC/MS/MS. The use of on-line SPE resulted in reduced sample preparation time and cleaner extracts, therefore minimizing ion suppression and HPLC back-pressures issues. The use of a 20 mM ammonium acetate-methanol system and a step gradient yielded intense ion species, excellent separation between the polar metabolites and the parent drug and sufficient selectivity for baseline resolution of the two positional isomers, SB 240103 and SB 218663. Pranlukast, its metabolites and the internal standard (SK&F 108566) were quantified using a turbo-ionspray interface by negative ion selected reaction monitoring (SRM). The lower limit of quantification (LLQ) for the assay was 10.0 ng ml-1 for Pranlukast and 1.00 ng ml-1 for its metabolites based on a 100 microliters plasma aliquot. The calibration curves were linear for analyte concentrations ranging from 10.0 to 2000 ng ml-1 for Pranlukast and 1.00 to 200 ng ml-1 for the metabolites. The calculated intra- and inter-assay precision from quality control (QC) samples resulted in mean variability values of less than 12% for all analytes. Pranlukast and its metabolites were shown to be stable under routine analysis conditions for clinical trial samples. The method provides automated sample analysis in a total cycle time of 5 min with improved robustness, sensitivity, selectivity, accuracy and reproducibility compared to the existing methodology.

Differences in platelet alpha-granule release between normals and immune thrombocytopenic patients and between young and old platelets

The risk of serious bleeding in patients with immune thrombocytopenic purpura (ITP) appears to be less than in comparably thrombocytopenic patients with megakaryocytic hypoplasia. It has been proposed that this difference is due to enhanced hemostatic activity of young platelets, which are increased in the circulation during ITP. We examined alpha-granule release in reticulated platelets (RP), which are thought to be the youngest circulating platelets, and in older non-reticulated platelets (non-RP) in normal human controls and ITP patients. Normal controls had a mean RP of 7%, compared with 42% in ITP patients. The mean concentration of thrombin receptor agonist peptide (TRAP) causing 50% of control RP to express CD62P (EC50) was 0.82+/-0.08 microM (SEM), significantly higher than the TRAP CD62P EC50 for RP in ITP, 0.57+/-0.06 microM (p = 0.04). Similarly, the TRAP EC50 for non-RP in controls, 0.84+/-0.09 microM, was significantly higher than in ITP, 0.56+/-0.07 microM (p = 0.03), suggesting that all platelets in ITP have an enhanced alpha-granule threshold response to TRAP compared with controls, while RP and older platelets within each patient group have similar threshold sensitivities to TRAP. By contrast, high-dose TRAP caused RP to express twice as much mean and total CD62P as non-RP in both ITP patients and controls (p <0.05 for both comparisons). We conclude that compared with controls, all platelets in ITP are primed to undergo alpha-granule release to TRAP, while in both ITP and controls, the newly circulating, reticulated platelets have the potential to contribute greater amounts of CD62P surface ligand compared with older platelets (non-RP) after stimulation. Both the increased RP% and enhanced platelet response to agonist in ITP may contribute to maintenance of hemostasis despite thrombocytopenia.

Evening dosing is associated with higher plasma concentrations of pranlukast, a leukotriene receptor antagonist, in healthy male volunteers

AIMS

To study the magnitude of differences in the pharmacokinetics of pranlukast, after morning and evening administration.

METHODS

Pranlukast (300 mg) was administered to 12 healthy male volunteers on two separate occasions, either in the morning or evening. Both doses were given 30 min after a standard high fat content meal. Blood samples were collected up to 18 h postdose. Plasma was assayed by high performance liquid chromatography. Standard pharmacokinetic and statistical analyses were performed.

RESULTS

Statistically significant (P < 0.05) increases were noted in AUC(o,t) (56%) and tmax (2.5 h) after evening administration. Cmax was 14% higher after evening dosing (95% C.I. 0.71-1.84).

CONCLUSIONS

Pranlukast bioavailability is apparently increased after evening dosing as compared with morning administration. Higher night-time and early morning plasma concentrations may confer additional therapeutic benefit at a time when asthmatics are at greatest risk of developing bronchospasm.