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Polycythemia vera (PV) is the most common Philadelphia chromosome-negative myeloproliferative neoplasm. Whereas low-risk patients are treated with aspirin and phlebotomy, high-risk patients receive cytoreductive therapy, which most commonly consists of hydroxyurea in the United States. Concerns about the long-term safety of hydroxyurea, as well as a desire for more efficacious and targeted therapy, have led to the development of novel therapies for high-risk patients with PV. Pegylated interferon (IFN) has shown promise in phase 2 studies of PV, and preliminary data from ongoing phase 3 studies suggest noninferiority as a frontline therapy. Efficient count control, tolerability, and even molecular responses as a salvage therapy have been demonstrated. Ropeginterferon-α-2b, a monopegylated IFN with a longer half-life and less frequent dose interval compared with recombinant or pegylated IFN, is an impressive agent in development. Ruxolitinib has a proven role as second-line therapy for PV, but an ongoing trial combining ruxolitinib and IFN as salvage therapy is under way. Early-phase clinical trials have also suggested that MDM2 inhibitors such as idasanutlin and histone deacetylase inhibitors should continue in their development. If these novel agents are able to modify the natural history of PV, the treatment paradigm in newly diagnosed patients will evolve from risk-adapted or reactive treatment toward early interventions.

Introduction: The development of clinically useful tracers for PET imaging is enormously challenging and expensive. The intranasal (IN) route of administration is purported to be a viable route for delivering drugs to the brain but has, as yet, not been investigated for the delivery of PET tracers. If the intranasal (IN) pathway presents a viable option, it extends the PET imaging field by increasing the number of tracers available for human use. Here we report the results of a rodent study testing the feasibility of the IN route to administer radiotracers for brain PET imaging., Methods: We used two different, well characterised, brain penetrant radiotracers, [ 18 F]fluorodeoxyglucose ([ 18 F]FDG) and [ 18 F]fallypride, and aimed to evaluate the pharmacokinetics after administration of the tracers via the intranasal route, and contrast this to intravenous administration. Image acquisition was carried out after tracer administration and arterial blood samples were collected at different time intervals, centrifuged to extract plasma and gamma counted. We hypothesised that [brain region]:[plasma] ratios would be higher via the intranasal route as there are two inputs, one directly from the nose to the brain, and another from the peripheral circulation. To assess the feasibility of using this approach clinically, we used these data to estimate radiation dosimetry in humans., Results: Contrary to our hypothesis, in case of both radiotracers, we did not see a higher ratio in the expected brain regions, except in the olfactory bulb, that is closest to the nose. It appears that the radiotracers move into the olfactory bulb region, but then do not progress further into other brain regions. Moreover, as the nasal cavity has a small surface area, the extrapolated dosimetry estimations for intranasal human imaging showed an unacceptably high level (15 mSv/MBq) of cumulative skin radiation exposure., Conclusions: Therefore, although an attractive route for brain permeation, we conclude that the intranasal route would present difficulties due to non-specific signal and radiation dosimetry considerations for brain PET imaging., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

The orexin system regulates sleep and arousal and is targeted by ACT-541468, a new dual orexin receptor antagonist (DORA). Healthy male subjects received a single oral dose of 5-200 mg to assess safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), mass balance, metabolism, and absolute bioavailability utilizing a 14 C-labeled, orally and intravenously (i.v.) administered microtracer. The drug was safe and well tolerated; the PK profile was characterized by quick absorption and elimination, with median time to reach maximum concentration (t max ) of 0.8-2.8 h and geometric mean terminal half-life (t 1/2 ) of 5.9-8.8 h. Clear dose-related effects on the central nervous system were observed at ≥25 mg, indicating a suitable PK-PD profile for a sleep-promoting drug, allowing for rapid onset and duration of action limited to the intended use. This comprehensive first-in-human study created a wealth of data, while saving resources in drug development., (© 2018 American Society for Clinical Pharmacology and Therapeutics.)

Synaptic vesicle glycoprotein 2A (SV2A) is ubiquitously present in presynaptic terminals. Here we report kinetic modeling and test-retest reproducibility assessment of the SV2A positron emission tomography (PET) radioligand [ 11 C]UCB-J in humans. Five volunteers were examined twice on the HRRT after bolus injection of [ 11 C]UCB-J. Arterial blood samples were collected for measurements of radiometabolites and free fraction. Regional time-activity curves were analyzed with 1-tissue (1T) and 2-tissue (2T) compartment models to estimate volumes of distribution ( V T ). Parametric maps were generated using the 1T model. [ 11 C]UCB-J metabolized fairly quickly, with parent fraction of 36 ± 13% at 15 min after injection. Plasma free fraction was 32 ± 1%. Regional time-activity curves displayed rapid kinetics and were well described by the 1T model, except for the cerebellum and hippocampus. V T values estimated with the 2T model were similar to 1T values. Parametric maps were of high quality and V T values correlated well with time activity curve (TAC)-based estimates. Shortening of acquisition time from 120 min to 60 min had a negligible effect on V T values. The mean absolute test-retest reproducibility for V T was 3-9% across regions. In conclusion, [ 11 C]UCB-J exhibited excellent PET tracer characteristics and has potential as a general purpose tool for measuring synaptic density in neurodegenerative disorders.

The serine hydrolase monoacylglycerol lipase (MGLL) converts the endogenous cannabinoid receptor agonist 2-arachidonoylglycerol (2-AG) and other monoacylglycerols into fatty acids and glycerol. Genetic or pharmacological inactivation of MGLL leads to elevation in 2-AG in the central nervous system and corresponding reductions in arachidonic acid and eicosanoids, producing antinociceptive, anxiolytic, and antineuroinflammatory effects without inducing the full spectrum of psychoactive effects of direct cannabinoid receptor agonists. Here, we report the optimization of hexafluoroisopropyl carbamate-based irreversible inhibitors of MGLL, culminating in a highly potent, selective, and orally available, CNS-penetrant MGLL inhibitor, 28 (ABX-1431). Activity-based protein profiling experiments verify the exquisite selectivity of 28 for MGLL versus other members of the serine hydrolase class. In vivo, 28 inhibits MGLL activity in rodent brain (ED 50 = 0.5-1.4 mg/kg), increases brain 2-AG concentrations, and suppresses pain behavior in the rat formalin pain model. ABX-1431 (28) is currently under evaluation in human clinical trials.

Epidermal growth factor receptor (EGFR)-activating mutations confer sensitivity to tyrosine kinase inhibitor (TKI) treatment for non-small-cell lung cancer (NSCLC). ASP8273 is a highly specific, irreversible, once-daily, oral, EGFR TKI that inhibits both activating and resistance mutations. This ASP8273 dose-escalation/dose-expansion study (NCT02192697) was undertaken in two phases. In phase I, Japanese patients (aged ≥20 years) with NSCLC previously treated with ≥1 EGFR TKI received escalating ASP8273 doses (25-600 mg) to assess safety/tolerability and to determine the maximum tolerated dose (MTD) and/or the recommended phase II dose (RP2D) by the Bayesian Continual Reassessment Method. In phase II, adult patients with T790M-positive NSCLC in Japan, Korea, and Taiwan received ASP8273 at RP2D to further assess safety/tolerability and determine antitumor activity, which was evaluated according to Simon's two-stage design (threshold response = 30%, expected response = 50%, α = 0.05, β = 0.1). Overall, 121 (n = 45 [33W/12M] phase I, n = 76 [48W/28M]) phase 2) patients received ≥1 dose of ASP8273. In phase I, RP2D and MTD were established as 300 and 400 mg, respectively. As 27 of the 63 patients treated with ASP8273 300 mg achieved a clinical response, ASP8273 was determined to have antitumor activity. The overall response rate at week 24 in all patients was 42% (n = 32/76; 95% confidence interval, 30.9-54.0). Median duration of progression-free survival was 8.1 months (95% confidence interval, 5.6, upper bound not reached). The most commonly reported treatment-related adverse event in phase II was diarrhea (57%, n = 43/76). ASP8273 300 mg was generally well tolerated and showed antitumor activity in Asian patients with both EGFR-activating and T790M mutations., (© 2018 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

Endogenous kappa opioids mediate pathological responses to stress in animal models. However, the relationship of the kappa opioid receptor (KOR) to life stress and to psychopathology in humans is not well described. This pilot study sought, for the first time, to quantify KOR in major depressive disorder (MDD) in vivo in humans using positron emission tomography (PET). KOR binding was quantified in vivo by PET imaging with the [ 11 C]GR103545 radiotracer in 13 healthy volunteers and 10 participants with current MDD. We examined the relationship between regional [ 11 C]GR103545 total volume of distribution (V T ) and diagnosis, childhood trauma, recent life stress, and, in a subsample, salivary cortisol levels during a modified Trier Social Stress Test (mTSST), amygdala, hippocampus, ventral striatum and raphe nuclei. Whole-brain voxel-wise analyses were also performed. [ 11 C]GR103545 V T did not differ significantly between MDD participants and healthy volunteers in the four a priori ROIs (p = 0.50). [ 11 C]GR103545 V T was unrelated to reported childhood adversity (p = 0.17) or recent life stress (p = 0.56). A trend-level inverse correlation was observed between [ 11 C]GR103545 V T and cortisol area-under-the curve with respect to ground during the mTSST (p = 0.081). No whole-brain voxel-wise contrasts were significant. Regional [ 11 C]GR103545 V T , a measure of in vivo KOR binding, does not differentiate MDD from healthy volunteers in this pilot sample. Future studies may examine KOR binding in subgroups of depressed individuals at increased risk for KOR abnormalities, including co-occurring mood and substance use disorders, as well as depression with psychotic features., (© 2018 Wiley Periodicals, Inc.)

Studies in nonhuman primates and humans have demonstrated that amphetamine-induced dopamine release in the cortex can be measured with [ 11 C]FLB 457 and PET imaging. This technique has been successfully used in recent clinical studies to show decreased dopamine transmission in the prefrontal cortex in schizophrenia and alcohol dependence. Here, we present data from a cohort of twelve healthy controls in whom an oral amphetamine challenge (0.5 mg kg -1 ) did not lead to a significant reduction in [ 11 C]FLB 457 BP ND (i.e., binding potential relative to non-displaceable uptake). Two factors that likely contributed to the inability to displace [ 11 C]FLB 457 BP ND in this cohort relative to successful cohorts are: (a) the acquisition of the baseline and post-amphetamine scans on different days as opposed to the same day and (b) the initiation of the post-amphetamine [ 11 C]FLB 457 scan at ∼5 hours as opposed to ∼3 hours following oral amphetamine. Furthermore, we show [ 11 C]FLB 457 reproducibility data from a legacy dataset to support greater variability in cortical BP ND when the test and retest scans are acquired on different days as compared to the same day. These results highlight the methodological challenges that continue to plague the field with respect to imaging dopamine release in the cortex., (© 2018 Wiley Periodicals, Inc.)

Glucokinase (GK) is an enzyme that plays an important role as a glucose sensor while maintaining whole body glucose homeostasis. Allosteric activators of GK (GKAs) have the potential to treat type 2 diabetes mellitus. To identify novel GKAs, a series of compounds based on a thiophenyl-pyrrolidine scaffold were designed and synthesized. In this series, compound 38 was found to inhibit glucose excursion in an oral glucose tolerance test (OGTT) in mice. Optimization of 38 using a zwitterion approach led to the identification of the novel GKA 59. GKA 59 exhibited potent blood glucose control in the OGTT test as well as a favorable safety profile. Owing to low pancreatic distribution, compound 59 primarily activates GK in the liver. This characteristic could overcome limitations of other GKAs, such as hypoglycemia, increased plasma triglycerides, and loss of efficacy., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Purpose: SPECT imaging with two radiotracers at the same time is feasible if two different radioisotopes are employed, given their distinct energy emission spectra. In the case of 123 I and 125 I, dual SPECT imaging is not straightforward: 123 I emits photons at a principal energy emission spectrum of 143.1-179.9 keV. However, it also emits at a secondary energy spectrum (15-45 keV) that overlaps with the one of 125 I and the resulting cross-talk of emissions impedes the accurate quantification of 125 I. In this paper, we describe three different methods for the correction of this cross-talk and the simultaneous in vivo [ 123 I]IBZM and [ 125 I]R91150 imaging of D 2/3 and 5-HT 2A receptors in the rat brain., Methods: Three methods were evaluated for the correction of the effect of cross-talk in a series of simultaneous, [ 123 I]IBZM and [ 125 I]R91150 in vivo and phantom SPECT scans. Method 1 employs a dual-energy window (DEW) approach, in which the cross-talk on 125 I is considered a stable fraction of the energy emitted from 123 I at the principal emission spectrum. The coefficient describing the relationship between the emission of 123 I at the principal and the secondary spectrum was estimated from a series of single-radiotracer [ 123 I]IBZM SPECT studies. In Method 2, spectral factor analysis (FA) is applied to separate the radioactivity from 123 I and 125 I on the basis of their distinct emission patterns across the energy spectrum. Method 3 uses a modified simplified reference tissue model (SRTM C ) to describe the kinetics of [ 125 I]R91150. It includes the coefficient describing the cross-talk on 125 I from 123 I in the model parameters. The results of the correction of cross-talk on [ 125 I]R91150 binding potential (BP ND ) with each of the three methods, using cerebellum as the reference region, were validated against the results of a series of single-radiotracer [ 123 I]R91150 SPECT studies. In addition, the DEW approach (Method 1), considered to be the most straightforward to apply of the three, was further applied in a dual-radiotracer SPECT study of the relationship between D 2/3 and 5-HT 2A receptor binding in the striatum, both at the voxel and at the regional level., Results: Average regional BP ND values of [ 125 I]R91150, estimated on the cross-talk corrected dual-radiotracer SPECT studies provided satisfactory correlations with the BP ND values for [ 123 I]R91150 from single-radiotracer studies: r = 0.92, p < 0.001 for Method 1, r = 0.92, p < 0.001 for Method 2, r = 0.92, p < 0.001, for Method 3. The coefficient describing the ratio of the 123 I-emitted radioactivity at the 125 I-emission spectrum to the radioactivity that it emits at its principal emission spectrum was 0.34 in vivo. Dual-radiotracer in vivo SPECT studies corrected with Method 1 demonstrated a positive correlation between D 2/3 and 5-HT 2A receptor binding in the rat nucleus accumbens at the voxel level. At the VOI-level, a positive correlation was confirmed in the same region (r = 0.78, p < 0.01)., Conclusion: Dual-radiotracer SPECT imaging using 123 I and 125 I-labeled radiotracers is feasible if the cross-talk of 123 I on the 125 I emission spectrum is properly corrected. The most straightforward approach is Method 1, in which a fraction (34%) of the radioactivity emitted from 123 I at its principal energy spectrum is subtracted from the measured radioactivity at the spectrum of 125 I. With this method, a positive correlation between the binding of [ 123 I]IBZM and [ 125 I]R91150 was demonstrated in the rat nucleus accumbens. This result highlights the interest of dual-radiotracer SPECT imaging to study multiple neurotransmitter systems at the same time and under the same biological conditions., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Forensic postmortem case interpretation can be challenging, in particular due to postmortem redistribution (PMR) phenomena. Recent studies have shown that computed tomography (CT)-guided collection of biopsy samples using a robotic arm (virtobot) provides a valuable tool for systematic studies on time-dependent PMR. Utilizing this strategy, several cases involving opioid use such as methadone, fentanyl, tramadol, codeine, oxycodone and hydrocodone were evaluated for time-dependent concentration changes and potential redistribution mechanisms. Upon admission to the institute (t1), blood (femoral and right ventricle heart blood) and tissue biopsy samples (lung, kidney, liver, spleen, thigh muscle and adipose tissue) were collected utilizing CT-guided biopsy. Approximately 24 h later (t2; mean 28 ± 15 h), during the autopsy, samples from the same body regions were collected manually and in addition brain tissue, gastric content, urine and left ventricle heart blood. Analysis was conducted with liquid chromatography tandem mass spectrometry. Significant time-dependent methadone concentration increases in femoral blood (pB) indicate the occurrence of PMR, however, ultimately not relevant for forensic interpretation. The main metabolite of methadone, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), showed a less significant trend for PMR. Redistribution by passive diffusion along the muscle-to-pB concentration gradient seems likely for methadone, but not for EDDP. Results for fentanyl suggest extensive PMR. Other opioids such as tramadol, codeine, hydrocodone and oxycodone showed no consistent trend for significant PMR. Overall, CT-guided biopsy sampling proved to be a valuable tool for the investigation of PMR mechanisms.

Purpose: Inhaled drug delivery is an attractive route by which to deliver drugs to lungs of patients with idiopathic pulmonary fibrosis (IPF). GSK3008348 is a potent and selective small molecule being developed as the first inhaled inhibitor of the αvβ6 integrin for the treatment of IPF. The phase 1 first-time-in-human clinical trial (NCT02612051) presented here was designed to investigate the safety, tolerability and pharmacokinetic (PK) profile of single doses of GSK3008348 in healthy participants., Methods: Single ascending doses of GSK3008348 were administered to three cohorts of eight healthy participants in a randomised, double-blind, placebo-controlled, 4-period crossover design. Safety, tolerability and PK were assessed after single doses of 1-3000 mcg given by nebulisation., Results: A total of 29 participants were enrolled and received at least one dose of study treatment. There were no serious adverse events (AE) reported in any participant. No trends or clinically important differences were noted in the incidence or intensity of AEs or other safety assessments. Maximum plasma concentrations of GSK3008348 were generally attained within approximately 30 min after start of nebulisation, with geometric mean terminal elimination half-lives ranging from 7.95 to 10.2 h. Exposures, as measured by area under the plasma concentration-time curve (AUC), were dose proportional across all doses where estimates were possible (100-3000 mcg). Dose normalised geometric mean C max increased with dose up to 3000 mcg. This supra proportionality was relatively modest, with a less than 3-fold increase over the range from 30 to 3000 mcg. The reason(s) for this observation are currently not known but may be due to slower absorption at the lowest doses. All exposures were within the exposure margins set by the non-clinical toxicity studies and so this is not expected to have any impact on safety., Conclusions: In summary, GSK3008348 was well tolerated at single doses up to 3000 mcg in healthy participants, and its PK profile was dose proportional at potentially clinically relevant doses (300-3000 mcg). These findings support further development of GSK3008348 as a novel inhaled treatment option for IPF.

Curative interferon and ribavirin sparing treatments for hepatitis C virus (HCV)-infected patients require a combination of mechanistically orthogonal direct acting antivirals. A shared component of these treatments is usually an HCV NS5A inhibitor. First generation FDA approved treatments, including the component NS5A inhibitors, do not exhibit equivalent efficacy against HCV virus genotypes 1-6. In particular, these first generation NS5A inhibitors tend to select for viral drug resistance. Ombitasvir is a first generation HCV NS5A inhibitor included as a key component of Viekira Pak for the treatment of patients with HCV genotype 1 infection. Since the launch of next generation HCV treatments, functional cure for genotype 1-6 HCV infections has been achieved, as well as shortened treatment duration across a wider spectrum of genotypes. In this paper, we show how we have modified the anchor, linker, and end-cap architecture of our NS5A inhibitor design template to discover a next generation NS5A inhibitor pibrentasvir (ABT-530), which exhibits potent inhibition of the replication of wild-type genotype 1-6 HCV replicons, as well as improved activity against replicon variants demonstrating resistance against first generation NS5A inhibitors.

New psychoactive substances (NPS), often referred as 'legal highs' or 'designer drugs', are derivatives and analogs of existing psychoactive drugs that are introduced in the recreational market to circumvent existing legislation on drugs of abuse. This work aims to review the state-of-the-art regarding chemical, molecular pharmacology, and in vitro and in vivo data on toxicokinetics of the potent synthetic cathinone α-pyrrolidinovalerophenone (α-PVP or flakka or zombie drug). Chemical, pharmacological, toxicological, and clinical effects of α-PVP were searched in PubMed (U.S. National Library of Medicine) and governmental websites without limitation of the period. α-PVP is a wide spread and easy to get special type of synthetic cathinone with seemingly powerful cocaine-like stimulant effects, high brain penetration, high liability for abuse and with increased risk of adverse effects such as tachycardia, agitation, hypertension, hallucinations, delirium, mydriasis, self-injury, aggressive behavior, and suicidal ideations. α-PVP undergoes extensive metabolism via different pathways and the α-PVP itself or its metabolites β-hydroxy-α-PVP and α-PVP lactam represent the main targets for toxicological analysis in urine. There is a limited knowledge regarding the short- and long-term effects of α-PVP and metabolites, and pharmacogenetic influence, hence further clinical and forensic toxicological studies are required. Moreover, since α-PVP cannot be detected with classic routine analysis procedures, statements on the frequency of their consumption cannot be made.

ASP7991 is a calcimimetic that acts on the calcium-sensing receptor on parathyroid cell membranes and suppresses parathyroid hormone (PTH) secretion in the treatment of secondary hyperparathyroidism. The mass balance and metabolite profile of [ 14 C]ASP7991 were investigated in six healthy male subjects after a single oral dose of [ 14 C]ASP7991 [1 mg, 18.5 kBq (500 nCi)] in solution. [ 14 C] radioactivity in plasma, urine and feces was analyzed using Accelerator mass spectrometry. ASP7991 was rapidly absorbed, metabolized and excreted. Mean recovery of [ 14 C] radioactivity in urine and feces was 30.08% and 49.31%, respectively, and mean total recovery of [ 14 C] radioactivity was 79.39%. The majority of [ 14 C] radioactivity in urine and feces was excreted within the first 72 h following administration. Seven metabolites were detected in plasma, urine and feces samples, and their structures were determined by mass spectrometry. The main metabolic pathways of ASP7991 in humans were predicted to be N-dealkylation, followed by N-acetylation and taurine conjugation to a carboxylic acid moiety. Our findings show that a mass balance study using micro radioactivity doses is suitable for elucidating the pharmacokinetics of the absorption, metabolism and excretion of administered drugs., (Copyright © 2018 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.)

Purpose: Idasanutlin, a selective small-molecule MDM2 antagonist in phase 3 testing for refractory/relapsed AML, is a non-genotoxic oral p53 activator. To optimize its dosing conditions, a number of clinical pharmacology characteristics were examined in this multi-center trial in patients with advanced solid tumors., Method: This was an open-label, single-dose, crossover clinical pharmacology study investigating the effects of strong CYP3A4 inhibition with posaconazole (Part 1), two new oral formulations (Part 2), as well as high-energy/high-fat and low-energy/low-fat meals (Part 3) on the relative bioavailability of idasanutlin. After completing Part 1, 2, or 3, patients could have participated in an optional treatment with idasanutlin. Clinical endpoints were pharmacokinetics (PK), pharmacodynamics (PD) of MIC-1 elevation (Part 1 only), and safety/tolerability., Results: The administration of posaconazole 400 mg BID × 7 days with idasanutlin 800 mg resulted in a slight decrease (7%) in C max and a modest increase (31%) in AUC for idasanutlin, a marked reduction in C max (~ 60%) and AUC0 (~ 50%) for M4 metabolite, and a minimal increase (~ 24%) in serum MIC-1 levels. C max and AUC were both 45% higher for the SDP formulation. While the low-fat meal caused a less than 20% increase in all PK exposure parameters with the 90% CI values just outside the upper end of the equivalence criteria (80-125%), the high-fat meal reached bioequivalence with dosing under fasting., Conclusion: In patients with solid tumors, multiple doses of posaconazole, a strong CYP3A4 inhibitor, minimally affected idasanutlin PK and PD without clinical significance. The SDP formulation improved rBA/exposures by ~ 50% without major food effect.

Background: Migraine is one of the most common headache disorders that greatly affect the quality of life. Selective serotonin (5-HT) receptor agonists such as triptamine-based drugs called triptans are used for treatment of migraine., Purpose: This study aimed to evaluate the pharmacokinetic (PK) and tolerability profiles of eletriptan hydrobromide (eletriptan HBr), a selective 5-hydroxytryptamine (also known as serotonin) 1B/1D receptor agonist, in Koreans and compare the results to those observed in non-Koreans in a previously published study., Patients and Methods: A randomized, open-label, single, and repeated-dose study was conducted in 16 healthy Korean male subjects using a four-treatment, four-period, and four-sequence crossover design (NCT01139515). The subjects received one of the following four treatments in each period: a single dose of 20, 40, 80 mg eletriptan HBr or a repeated oral dose of 40 mg 2 h apart. Blood samples were collected before and up to 26 h after dosing for quantification of plasma eletriptan concentration by high-performance liquid chromatography tandem-mass spectrometry. The PK parameters were estimated using noncompartmental methods. Ethnicity differences between Korean and non-Korean subjects were identified using geometric mean ratios and 90% confidence intervals (CIs) of dose-normalized maximum plasma concentration (C max ) and dose-normalized area under the plasma concentration versus time curve from 0 h to the last measurable concentration (AUC 0-t )., Results: After single-dose administration of eletriptan HBr to Korean subjects, the mean C max and AUC 0-t increased linearly with dose. Comparable total systemic exposures were observed in the 2 h apart 40 mg repeated and single 80 mg dose. The geometric mean ratios (90% CIs) of the dose-normalized C max and AUC 0-t of Korean subjects were similar to those of non-Korean subjects reported in the literature. The adverse events observed were transient and mild in severity., Conclusion: Eletriptan HBr showed linear PK and was well tolerated in Korean subjects. The PK and tolerability of eletriptan HBr did not differ between Korean and non-Korean subjects., Competing Interests: Disclosure Jeffrey Alderman is employed by Pfizer, Inc. The authors report no other conflicts of interest in this work.

Glucagon-like peptide-1 (GLP-1) receptor agonists (liraglutide, exenatide, lixisenatide) have recently been used as anti-diabetes drugs. We examined relationships of the binding occupancy of GLP-1 receptors (Φ) and their clinical efficacy after administration of GLP-1 receptor agonists. Next, by focusing on changes of GLP-1 concentration after administration of dipeptidyl peptidase-4 (DPP-4) inhibitors (vildagliptin, alogliptin, sitagliptin, linagliptin), we analyzed the relationship between Φ and clinical efficacy. Furthermore, using Φ as a common parameter, we compared the clinical efficacy elicited by GLP-1 receptor agonists and DPP-4 inhibitors using a theoretical analysis method. The present results showed that GLP-1 receptor agonists produced their clinical effect at a relatively low level of Φ (1.1-10.7%) at a usual dose. Furthermore, it was suggested that the drugs might achieve their full effect at an extraordinarily low level of Φ. It was also revealed that the Φ value of DPP-4 inhibitors (0.83-1.3%) was at the lower end or lower than that of GLP-1 receptor agonists at a usual dose. Accordingly, the predicted value for hemoglobin A 1c (HbA 1c ) reduction after administration of the GLP-1 receptor agonists was higher than that of DPP-4 inhibitors. We clarified the differences between the therapeutic effects associated with GLP-1 receptor agonists and DPP-4 inhibitors theoretically. Together, the present findings provide a useful methodology for proper usage of GLP-1 receptor agonists and DPP-4 inhibitors.

Synthetic cathinones inhibit monoamine transporters, such as serotonin, norepinephrine, and dopamine transporters, and act on the central nervous system via increasing synaptic concentrations of monoamines. These compounds, which are highly addictive and potentially poisonous, are new psychoactive substances. In this study, we investigated the toxicokinetics of the synthetic cathinone, α-pyrrolidinohexanophenone (α-PHP), and assessed the relationship between the toxicokinetics and the long-term clinical symptoms induced by α-PHP in a male patient. The patient (39 years old) suddenly started uttering inarticulate words and demonstrating incomprehensible behavior in his house, and was brought to the emergency department of Iwate Medical University hospital. He presented with psychotic symptoms, such as hallucinations and delusion; however, his vital signs were normal. The hallucinations and delusion improved by the third day of hospitalization. Toxicological analysis was performed using liquid chromatography-tandem mass spectrometry with QuEChERS extraction. α-PHP was detected in his serum at a concentration of 175 ng/mL on his arrival at the hospital. His serum concentrations of α-PHP were serially determined and their natural logarithms were plotted against time after arrival. Although serum concentrations at early time points were lacking, the obtained curve was consistent with a two-compartment model and indicated a serum elimination half-life of 37 h. The long-lasting psychotic symptoms induced by synthetic cathinones appear to be correlated with their toxicokinetic characteristics, such as their long half-lives. Finally, interpreting the toxicokinetics of synthetic cathinones may provide useful information for the toxicological assessment of new psychoactive substances for forensic and clinical purposes.

Holmes's tremor (HT) is assumed to be the result of coexistence of nigrostriatal dopaminergic system impairment and the lesion of cerebello-thalamic pathways. It was suggested that dopaminergic deficiency is responsible for rest tremor, and lack of compensatory cerebellar function leads to spill of tremor into voluntary movements. Cases of HT with and without abnormalities of the presynaptic part of dopaminergic nigrostriatal were published and these findings raised the question of possibility of the postsynaptic lesion. Three patients with HT diagnosed according to criteria of Consensus Statement on Tremor were studied. In all of them SPECT imaging with ligands of presynaptic (I 123-FP CIT-DaTSCAN) and postsynaptic (I 123-iodobenzamide-IBZM) nigrostriatal dopaminergic neurons was performed. Indices of uptake in caudate and putamen normalized to nonspecific uptake in occipital cortex and indices of asymmetry for each whole striatum as well as for putamen and caudate separately were calculated. SPECT studies did not reveal asymmetry of DaTSCAN and IBZM binding in striatum in all studied subjects. The current clinical diagnostic criteria of HT are presumably insufficiently specific and when using them we identify patients both with and without the involvement of dopaminergic system. These two groups may represent tremor disorders of similar phenomenology but of different pathomechanism.

The identification of new sleep drugs poses particular challenges in drug discovery owing to disease-specific requirements such as rapid onset of action, sleep maintenance throughout major parts of the night, and absence of residual next-day effects. Robust tools to estimate drug levels in human brain are therefore key for a successful discovery program. Animal models constitute an appropriate choice for drugs without species differences in receptor pharmacology or pharmacokinetics. Translation to man becomes more challenging when interspecies differences are prominent. This report describes the discovery of the dual orexin receptor 1 and 2 (OX 1 and OX 2 ) antagonist ACT-541468 out of a class of structurally related compounds, by use of physiology-based pharmacokinetic and pharmacodynamic (PBPK-PD) modeling applied early in drug discovery. Although all drug candidates exhibited similar target receptor potencies and efficacy in a rat sleep model, they exhibited large interspecies differences in key factors determining their pharmacokinetic profile. Human PK models were built on the basis of in vitro metabolism and physicochemical data and were then used to predict the time course of OX 2 receptor occupancy in brain. An active ACT-541468 dose of 25 mg was estimated on the basis of OX 2 receptor occupancy thresholds of about 65% derived from clinical data for two other orexin antagonists, almorexant and suvorexant. Modeling predictions for ACT-541468 in man were largely confirmed in a single-ascending dose trial in healthy subjects. PBPK-PD modeling applied early in drug discovery, therefore, has great potential to assist in the identification of drug molecules when specific pharmacokinetic and pharmacodynamic requirements need to be met., (Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.)

Because of the avoidance of first pass metabolic effects due to direct and rapid absorption with improved permeability, intranasal route represents a good alternative for extravascular drug administration. The aim of the study was to investigate the intranasal pharmacokinetics of two anti-migraine drugs (zolmitriptan and eletriptan), using retro-orbital sinus and jugular vein sites sampling. In a parallel study design, healthy male Sprague-Dawley (SD) rats aged between 8 and 12weeks were divided into groups (n=4 or 5/group). The animals of individual groups were dosed intranasal (~1.0mg/kg) and oral doses of 2.1mg/kg of either zolmitriptan or eletriptan. Serial blood sampling was performed from jugular vein or retro-orbital site and plasma samples were analyzed for drug concentrations using LC-MS/MS assay. Standard pharmacokinetics parameters such as T max , C max , AUC last , AUC 0-inf and T 1/2 were calculated and statistics of derived parameters was performed using unpaired t-test. After intranasal dosing, the mean pharmacokinetic parameters C max and AUC inf of zolmitriptan/eletriptan showed about 17-fold and 3-5-fold higher values for retro-orbital sampling as compared to the jugular vein sampling site. Whereas after oral administration such parameters derived for both drugs were largely comparable between the two sampling sites and statistically non-significant. In conclusion, the assessment of plasma levels after intranasal administration with retro-orbital sampling would result in spurious and misleading pharmacokinetics., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This study elucidates the physical properties of sono-crystallised micro/nano-sized acetaminophen/paracetamol (PMOL) and monitors its possible transformation from polymorphic form I (monoclinic) to form II (orthorhombic). Hydrophilic Plasdone® S630 copovidone (S630), N-vinyl-2-pyrrolidone and vinyl acetate copolymer, and methacrylate-based cationic copolymer, Eudragit® EPO (EPO), were used as polymeric carriers to prepare drug/polymer binary mixtures. Commercially available PMOL was crystallised under ultra sound sonication to produce micro/nano-sized (0.2-10 microns) crystals in monoclinic form. Homogeneous binary blends of drug-polymer mixtures at various drug concentrations were obtained via a thorough mixing. The analysis conducted via the single X-ray crystallography determined the detailed structure of the crystallised PMOL in its monoclinic form. The solid state and the morphology analyses of the PMOL in the binary blends evaluated via differential scanning calorimetry (DSC), modulated temperature DSC (MTDSC), scanning electron microscopy (SEM) and hot stage microscopy (HSM) revealed the crystalline existence of the drug within the amorphous polymeric matrices. The application of temperature controlled X-ray diffraction (VTXRPD) to study the polymorphism of PMOL showed that the most stable form I (monoclinic) was altered to its less stable form II (orthorhombic) at high temperature (>112°C) in the binary blends regardless of the drug amount. Thus, VTXRD was used as a useful tool to monitor polymorphic transformations of crystalline drug (e.g. PMOL) to assess their thermal stability in terms of pharmaceutical product development and research.

The P-glycoprotein (Pgp) transporter reduces the penetration of a chemically diverse range of neurotherapeutics at the blood-brain barrier, but the molecular features of drugs and drug-Pgp interactions that drive transport remain to be clarified. In particular, the triptan neurotherapeutics, eletriptan (ETT) and sumatriptan (STT), were identified to have a >10-fold difference in transport rates despite being from the same drug class. Consistent with these transport differences, ETT activated Pgp-mediated ATP hydrolysis ∼2-fold, whereas STT slightly inhibited Pgp-mediated ATP hydrolysis by ∼10%. The interactions between them were also noncompetitive, suggesting that they occupy different binding sites on the transporter. Despite these differences, protein fluorescence spectroscopy revealed that the drugs have similar affinity to the transporter. NMR with Pgp and the drugs showed that they have distinct interactions with the transporter. Tertiary conformational changes probed by acrylamide quenching of Pgp tryptophan fluorescence with the drugs and a nonhydrolyzable ATP analog implied that the STT-bound Pgp must undergo larger conformational changes to hydrolyze ATP than ETT-bound Pgp. These results and previous transport studies were used to build a conformationally driven model for triptan transport with Pgp where STT presents a higher conformational barrier for ATP hydrolysis and transport than ETT., (Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Purpose: To analyze the effect of liver steatosis and obesity on pharmacokinetic profile of two structurally-related liver-selective NO-donors - V-PYRRO/NO and V-PROLI/NO., Methods: C57BL/6 mice were fed control or high-fat diet for 15 weeks to induced liver steatosis and obesity (HFD mice). Pharmacokinetics and renal elimination studies were conducted in vivo following iv dosing of V-PYRRO/NO and V-PROLI/NO (0.03mmol/kg). Hepatic clearance was evaluated ex vivo in the isolated perfused mice liver and in vitro with the use of liver microsomes., Results: V-PYRRO/NO and V-PROLI/NO, despite similar structure, displayed different pharmacokinetic properties. V-PYRRO/NO was uptaken and metabolized by the liver, while V-PROLI/NO was eliminated unchanged with urine. In HFD mice, despite increased CYP450 metabolism of V-PYRRO/NO the elimination rate was slower most likely due to the impairment of hepatic microcirculation caused by liver fat accumulation. In turn, in HFD mice renal clearence of V-PROLI/NO was accelerated and volume of distribution was increased most likely due to additional intracellular water in HFD mice., Conclusions: The pharmacokinetics of V-PROLI/NO, the novel proline-based analog of V-PYRRO/NO with additional single carboxylic acid moiety, attached to the molecule of V-PYRRO/NO to improve the water solubility, was differently affected by liver steatosis and obesity as compared with the parent compound V-PYRRO/NO., (Copyright © 2017 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.)

Dipeptidyl peptidase-4 (DPP-4) inhibitors are used clinically as therapeutic agents for the treatment of diabetes. To determine the rate of DPP-4 inhibition induced by these inhibitors, pharmacokinetic and pharmacodynamic parameters were used to theoretically examine the relationship between the rate of DPP-4 inhibition and clinical efficacy following the administration of four different DPP-4 inhibitors (sitagliptin, vildagliptin, alogliptin, linagliptin) by focusing on the increase in the level of glucagon-like peptide-1 (GLP-1) induced by their administration. On the basis of the relationship shown, changes in clinical efficacy in association with dose change were examined in order to discuss clinical dosage from the standpoint of proper usage. The results indicate that a high rate of DPP-4 inhibition is necessary for the onset of the effect of an administered the DPP-4 inhibitor and that the average value for the DPP-4 inhibition rate can be utilized as a common parameter of clinical efficacy. Furthermore, the efficacy profiles of the present DPP-4 inhibitors could be demonstrated on the basis of an increase in the GLP-1 level. It is considered that the present findings provide useful information for promoting the proper clinical use of DPP-4 inhibitors. Copyright © 2016 John Wiley & Sons, Ltd., (Copyright © 2016 John Wiley & Sons, Ltd.)

Alterations in the dopamine system are hypothesized to influence the expression of social anxiety disorder (SAD) symptoms. However, molecular imaging studies comparing dopamine function between patients and control subjects have yielded conflicting results. Importantly, while all previous investigations focused on the striatum, findings from activation and blood flow studies indicate that prefrontal and limbic brain regions have a central role in the pathophysiology. The objective of this study was to investigate extrastriatal dopamine D2-receptor (D2-R) availability in SAD. We examined 12 SAD patients and 16 healthy controls using positron emission tomography and the high-affinity D2-R radioligand [ 11 C]FLB457. Parametric images of D2-R binding potential were derived using the Logan graphical method with cerebellum as reference region. Two-tailed one-way independent ANCOVAs, with age as covariate, were used to examine differences in D2-R availability between groups using both region-based and voxel-wise analyses. The region-based analysis showed a medium effect size of higher D2-R levels in the orbitofrontal cortex (OFC) in patients, although this result did not remain significant after correction for multiple comparisons. The voxel-wise comparison revealed elevated D2-R availability in patients within OFC and right dorsolateral prefrontal cortex after correction for multiple comparisons. These preliminary results suggest that an aberrant extrastriatal dopamine system may be part of the disease mechanism in SAD., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

We recently reported a class of novel tissue-selective androgen receptor modulators (SARMs), represented by a naphthalene derivative A. However, their pharmacokinetic (PK) profiles were poor due to low metabolic stability. To improve the PK profiles, we modified the hydroxypyrrolidine and benzonitrile substituents of 4-(pyrrolidin-1-yl)benzonitrile derivative B, which had a comparable potency as that of compound A. This optimization led us to further modifications, which improved metabolic stability while maintaining potent androgen agonistic activity. Among the synthesized compounds, (2S,3S)-2,3-dimethyl-3-hydroxylpyrrolidine derivative 1c exhibited a suitable PK profile and improved metabolic stability. Compound 1c demonstrated significant efficacy in levator ani muscle without increasing the weight of the prostate in an in vivo study. In addition, compound 1c showed agonistic activity in the CNS, which was detected using sexual behavior induction assay., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Mutant epidermal growth factor receptor (EGFR) is a major driver of non-small-cell lung cancer (NSCLC). Marketed first generation inhibitors, such as erlotinib, effect a transient beneficial response in EGFR mutant NSCLC patients before resistance mechanisms render these inhibitors ineffective. Secondary oncogenic EGFR mutations account for approximately 50% of relapses, the most common being the gatekeeper T790M substitution that renders existing therapies ineffective. The discovery of PF-06459988 (1), an irreversible pyrrolopyrimidine inhibitor of EGFR T790M mutants, was recently disclosed.1 Herein, we describe our continued efforts to achieve potency across EGFR oncogenic mutations and improved kinome selectivity, resulting in the discovery of clinical candidate PF-06747775 (21), which provides potent EGFR activity against the four common mutants (exon 19 deletion (Del), L858R, and double mutants T790M/L858R and T790M/Del), selectivity over wild-type EGFR, and desirable ADME properties. Compound 21 is currently being evaluated in phase-I clinical trials of mutant EGFR driven NSCLC.

We previously reported the design of spirooxindoles with two identical substituents at the carbon-2 of the pyrrolidine core as potent MDM2 inhibitors. In this paper we describe an extensive structure-activity relationship study of this class of MDM2 inhibitors, which led to the discovery of 60 (AA-115/APG-115). Compound 60 has a very high affinity to MDM2 (K i < 1 nM), potent cellular activity, and an excellent oral pharmacokinetic profile. Compound 60 is capable of achieving complete and long-lasting tumor regression in vivo and is currently in phase I clinical trials for cancer treatment.

Background Trifluridine, a thymidine-based chemotherapeutic, has limited bioavailability after clinical administration as it is rapidly degraded via thymidine phosphorylase. An oral combination tablet combines trifluridine with a potent thymidine phosphorylase inhibitor, tipiracil hydrochloride. This study's objective was to evaluate whether trifluridine/tipiracil (TAS-102) administration increases trifluridine exposure vs trifluridine alone. Methods This open-label pharmacokinetic study randomly assigned patients with advanced solid tumors into two groups. On the morning of day 1, one group received a single 35 mg/m 2 dose of trifluridine/tipiracil and the other group received a single 35-mg/m 2 dose of trifluridine. Both groups received trifluridine/tipiracil 35 mg/m 2 on the evening of day 1, then twice daily on days 2-5 and 8-12 in a 28-day cycle. Results Twenty patients received an initial one-time dose of trifluridine alone and 19 other patients received an initial dose of trifluridine/tipiracil. Trifluridine area under the curve (AUC 0-last ) and maximum observed plasma concentrations (C max ) were approximately 37- and 22-fold higher, respectively, with trifluridine/tipiracil vs trifluridine alone. Plasma concentrations of the major metabolite of trifluridine were lower following the administration of trifluridine/tipiracil vs trifluridine alone. Conclusion Tipiracil administered in combination with trifluridine significantly increased exposure to trifluridine compared with trifluridine alone.

Aims: The selective endothelin (ET) A receptor antagonist atrasentan has been shown to lower albuminuria in North American and Asian patients with type 2 diabetes and nephropathy. As drug responses to many drugs may differ between North American and Asian populations, we assessed the influence of geographical region on the albuminuria and fluid retention response to atrasentan., Materials and Methods: Two 12-week double-blind randomised controlled trials were performed with atrasentan 0.75 or 1.25 mg/d vs placebo in patients with type 2 diabetes and nephropathy. The efficacy endpoint was the percentage change in albuminuria. Bodyweight change, a proxy of fluid retention, was used as a safety endpoint. Pharmacodynamics were determined in Asians (N = 77) and North Americans (N = 134). Atrasentan plasma concentration was measured in 161 atrasentan-treated patients., Results: Mean albuminuria reduction in Asian, compared to North American, patients was, respectively, -34.4% vs -26.3% for 0.75 mg/d ( P  = .44) and -48.0% vs -28.9% for 1.25 mg/d ( P  = .035). Bodyweight gain did not differ between North American and Asian populations. Atrasentan plasma concentrations were higher in Asians compared to North Americans and correlated with albuminuria response (7.2% albuminuria reduction per doubling atrasentan concentration; P  = .024). Body surface area (β = -1.09 per m 2 ; P  < .001) and bilirubin, as a marker of hepatic organic anion transporter activity, (β = 0.69 per mg/dL increment; P  = .010) were independent determinants of atrasentan plasma concentration; correction by body surface area and bilirubin left no significant difference in plasma concentration between Asian and North American populations., Conclusion: The higher exposure and albuminuria reduction of atrasentan in Asian patients is not associated with more fluid retention, suggesting that Asian patients are less sensitive to atrasentan-induced sodium retention., (© 2016 John Wiley & Sons Ltd.)

Type 1 Gaucher disease is a rare genetic disease characterized by enzymatic deficit leading to glucosylceramide overload in body tissues (lysosomal overload disease). Standard treatment is based on substitutive enzyme therapy by intravenous perfusion. A new drug for oral administration, eliglustat, was recently awarded marketing approval in Europe and the USA. Eliglustat acts by reducing the enzyme substrate. Eliglustat is mainly eliminated by a CYP2D6 pathway. CYP2D6 exhibits genetic variability or expression, leading to 20-fold differences in serum levels. In marketing approval documents, both the FDA and the EMA mention the requirement for CYP2D6 genotyping before prescribing eliglustat: the drug is contraindicated for ultra-rapid metabolizers (under-dosing inefficacy) and slow metabolizers should be given a 50% reduced daily dose (risk of overdose-related adverse effects). Finally, potential drug interactions (inhibition or induction of CYP2D6 or CYP3A40) are also dependent on CYP2D6 genotyping, such that prescribers must be aware of a patient's genotype before prescribing eliglustat., (Copyright © 2017 Société française de pharmacologie et de thérapeutique. Published by Elsevier Masson SAS. All rights reserved.)

A novel series of pyrrolidine-containing GPR40 agonists is described as a potential treatment for type 2 diabetes. The initial pyrrolidine hit was modified by moving the position of the carboxylic acid, a key pharmacophore for GPR40. Addition of a 4-cis-CF 3 to the pyrrolidine improves the human GPR40 binding K i and agonist efficacy. After further optimization, the discovery of a minor enantiomeric impurity with agonist activity led to the finding that enantiomers (R,R)-68 and (S,S)-68 have differential effects on the radioligand used for the binding assay, with (R,R)-68 potentiating the radioligand and (S,S)-68 displacing the radioligand. Compound (R,R)-68 activates both G q -coupled intracellular Ca 2+ flux and G s -coupled cAMP accumulation. This signaling bias results in a dual mechanism of action for compound (R,R)-68, demonstrating glucose-dependent insulin and GLP-1 secretion in vitro. In vivo, compound (R,R)-68 significantly lowers plasma glucose levels in mice during an oral glucose challenge, encouraging further development of the series.

Purpose: Molecular imaging of the D 2/3 receptor is widely used in neuropsychiatric research. Non-displaceable binding potential (BP ND ) is a very popular quantitative index, defined as the product of the receptor concentration (B avail ) and the radiotracer affinity for the receptor (1/appK d ). As the appK d is influenced by parameters such as the endogenous neurotransmitter dynamics, it often constitutes a confounding factor in research studies. A simplified method for absolute quantification of both these parameters would be of great interest in this context. Here, we describe the use of a partial saturation protocol that permits to produce an in vivo Scatchard plot and thus estimate B avail and appK d separately , through a single dynamic SPECT session. To validate this approach, a multi-injection protocol is used for the full kinetic modeling of [ 123 I]IBZM using a 3-tissue compartment, 7-parameter model (3T-7k). Finally, more "classic" BP ND estimation methods are also validated against the results of the 3T-7k., Methods: Twenty-nine male rats were used. Binding parameters were estimated using the 3T-7k in a multi-injection protocol. A partial saturation protocol was applied at the region- and voxel-level and results were compared to those obtained with the 3T-7k model. The partial saturation protocol was applied after an adenovirus-mediated D 2 receptor striatal overexpression and in an amphetamine-induced dopamine release paradigm. The Simplified Reference Tissue Model (SRTM), the Logan's non-invasive graphical analysis (LNIGA) and a simple standardized uptake ratio (SUR) method were equally applied., Results: The partial saturation experiments gave similar values as the 3T-7k both at the regional and voxel-level. After adenoviral-mediated D 2 -receptor overexpression, an increase in B avail by approximately 18% was observed in the striatum. After amphetamine administration, a 16.93% decrease in B avail (p<0.05) and a 39.12% increase (p<0.01) in appK d was observed. BP ND derived from SRTM, LNIGA and SUR correlated well with the B avail values from the 3T-7k (r=0.84, r=0.84 and r=0.83, respectively, p<0.0001 for all correlations)., Conclusion: A partial saturation protocol permits the non-invasive and time-efficient estimation of B avail and appK d separately. Given the different biological phenomena that underlie these parameters, this method may be applied for the in-depth study of the dopaminergic system in translational molecular imaging studies. It can detect the biological variations in these parameters, dissociating the variations in receptor density (B avail ) from affinity (1/appK d ), which reflects the interactions of the receptor with its endogenous ligand., (Copyright © 2016 Elsevier Inc. All rights reserved.)

1. Unbound brain drug concentration (C b,u ), a valid surrogate of interstitial fluid drug concentration (C ISF ), cannot be directly determined in humans, which limits accurately defining the human C b,u :C p,u of investigational molecules. 2. For the H 3 R antagonist (1R,3R)-N-ethyl-3-fluoro-3-[3-fluoro-4-(pyrrolidin-1-lmethyl)phenyl]cyclobutane-1-carboxamide (PF-03654746), we interrogated C b,u :C p,u in humans and nonhuman primate (NHP). 3. In rat, PF-03654746 achieved net blood-brain barrier (BBB) equilibrium (C b,u :C p,u of 2.11). 4. In NHP and humans, the PET receptor occupancy-based C p,u IC 50 of PF-03654746 was 0.99 nM and 0.31 nM, respectively, which were 2.1- and 7.4-fold lower than its in vitro human H 3 K i (2.3 nM). 5. In an attempt to understand this higher-than-expected potency in humans and NHP, rat-derived C b,u :C p,u of PF-03654746 was integrated with C p,u IC 50 to identify unbound (neuro) potency of PF-03654746, nIC 50 . 6. The nIC 50 of PF-03654746 was 2.1 nM in NHP and 0.66 nM in human which better correlated (1.1- and 3.49-fold lower) with in vitro human H 3 K i (2.3 nM). 7. This correlation of the nIC 50 and in vitro hH 3 K i suggested the translation of net BBB equilibrium of PF-03654746 from rat to NHP and humans, and confirmed the use of C p,u as a reliable surrogate of C b,u . 8. Thus, nIC 50 quantitatively informed the human C b,u :C p,u of PF-03654746.

The main route of elimination of vildagliptin, which is an inhibitor of dipeptidyl peptidase-4 (DPP-4), in humans is cyano group hydrolysis to produce a carboxylic acid metabolite M20.7. Our in vitro study previously demonstrated that DPP-4 itself greatly contributed to the hydrolysis of vildagliptin in mouse, rat, and human livers. To investigate whether hepatic DPP-4 contributes to the hydrolysis of vildagliptin in vivo, in the present study, we conducted in vivo pharmacokinetics studies of vildagliptin in mice coadministered with vildagliptin and sitagliptin, which is another DPP-4 inhibitor, and also in streptozotocin (STZ)-induced diabetic mice. The area under the plasma concentration-time curve (AUC) value of M20.7 in mice coadministered with vildagliptin and sitagliptin was significantly lower than that in mice administered vildagliptin alone (P < 0.01). Although plasma DPP-4 expression level was increased 1.9-fold, hepatic DPP-4 activity was decreased in STZ-induced diabetic mice. The AUC values of M20.7 in STZ-induced diabetic mice were lower than those in control mice (P < 0.01). Additionally, the AUC values of M20.7 significantly positively correlated with hepatic DPP-4 activities in the individual mice (Rs = 0.943, P < 0.05). These findings indicated that DPP-4 greatly contributed to the hydrolysis of vildagliptin in vivo and that not plasma, but hepatic DPP-4 controlled pharmacokinetics of vildagliptin. Furthermore, enzyme assays of 23 individual human liver samples showed that there was a 3.6-fold interindividual variability in vildagliptin-hydrolyzing activities. Predetermination of the interindividual variability of hepatic vildagliptin-hydrolyzing activity might be useful for the prediction of blood vildagliptin concentrations in vivo., (Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.)

We describe the research that led to the discovery of compound 40 (ruzasvir, MK-8408), a pan-genotypic HCV nonstructural protein 5A (NS5A) inhibitor with a "flat" GT1 mutant profile. This NS5A inhibitor contains a unique tetracyclic indole core while maintaining the imidazole-proline-valine Moc motifs of our previous NS5A inhibitors. Compound 40 is currently in early clinical trials and is under evaluation as part of an all-oral DAA regimen for the treatment of chronic HCV infection.

Starting from the initial lead 4-phenylthiazole 18, a modest HCV inhibitor (EC 50 = 9440 nM), a series of structurally related thiazole derivatives has been identified as a novel chemical class of potent and selective HCV NS5A inhibitors. The introduction of a carboxamide group between the thiazole and pyrrolidine ring (42) of compound 18 resulted in a dramatic increase in activity (EC 50 = 0.92 nM). However, 42 showed only moderate pharmacokinetic properties and limited oral bioavalability of 18.7% in rats. Further optimization of the substituents at the 4-position of the thiazole ring and pyrrolidine nitrogen of the lead compound 42 led to the identification of compound 57, a highly potent and selective NS5A inhibitor of HCV (EC 50 = 4.6 nM), with greater therapeutic index (CC 50 /EC 50 > 10000). Pharmacokinetic studies revealed that compound 57 had a superior oral exposure and desired bioavailability of 45% after oral administration in rats.

Methylenedioxypyrovalerone (MDPV) has emerged in recent years as a recreational substance with psychostimulant properties. In this study, in vitro metabolites of MDPV were characterized based on liquid chromatography/quadrupole-time-of-flight mass spectrometry (LC/QTOF MS). MDPV was incubated with human liver microsomes, human recombinant cDNA-expressed cytochrome P450 enzymes and flavin monooxygenase (FMO). MDPV was metabolized to yield eight metabolites (M1-M8) with major metabolic reactions such as demethylenation and oxidation. Among them, M6 was assigned as an N-oxide metabolite. FMO was found to be a principal enzyme responsible for the formation of M6; FMO1 and FMO3 were the main enzymes involved in N-oxidation of MDPV., (Copyright © 2016 Elsevier B.V. All rights reserved.)

CEP-26401 is a novel orally active, brain-penetrant, high-affinity histamine H3 receptor (H3R) antagonist, with potential therapeutic utility in cognition enhancement. Two randomized, double-blind, placebo-controlled dose escalation studies with single (0.02 to 5 mg) or multiple administration (0.02 to 0.5 mg once daily) of CEP-26401 were conducted in healthy subjects. Plasma and urine samples were collected to investigate CEP-26401 pharmacokinetics. Pharmacodynamic endpoints included a subset of tasks from the Cambridge Neuropsychological Test Automated Battery (CANTAB) and nocturnal polysomnography. Population pharmacokinetic-pharmacodynamic modeling was conducted on one CANTAB and one polysomnography parameter of interest. CEP-26401 was slowly absorbed (median tmax range 3-6 hours) and the mean terminal elimination half-life ranged from 24-60 hours. Steady-state plasma concentrations were achieved within six days of dosing. CEP-26401 exhibits dose- and time-independent pharmacokinetics, and renal excretion is a major elimination pathway. CEP-26401 had a dose-dependent negative effect on sleep, with some positive effects on certain CANTAB cognitive parameters seen at lower concentrations. The derived three compartment population pharmacokinetic model, with first-order absorption and elimination, accurately described the available pharmacokinetic data. CEP-26401 was generally well tolerated up to 0.5 mg/day with most common treatment related adverse events being headache and insomnia. Further clinical studies are required to establish the potential of low-dose CEP-26401 in cognition enhancement., (© The Author(s) 2016.)

Aiming to develop new artemisinin-based combination therapy (ACT) for malaria, antimalarial effect of a new series of pyrrolidine-acridine hybrid in combination with artemisinin derivatives was investigated. Synthesis, antimalarial and cytotoxic evaluation of a series of hybrid of 2-(3-(substitutedbenzyl)pyrrolidin-1-yl)alkanamines and acridine were performed and mode of action of the lead compound was investigated. In vivo pharmacodynamic properties (parasite clearance time, parasite reduction ratio, dose and regimen determination) against multidrug resistant (MDR) rodent malaria parasite and toxicological parameters (median lethal dose, liver function test, kidney function test) were also investigated. 6-Chloro-N-(4-(3-(3,4-dimethoxybenzyl)pyrrolidin-1-yl)butyl)-2-methoxyacridin-9-amine (15c) has shown a dose dependent haem bio-mineralization inhibition and was found to be the most effective and safe compound against MDR malaria parasite in Swiss mice model. It displayed best antimalarial potential with artemether (AM) in vitro as well as in vivo. The combination also showed favourable pharmacodynamic properties and therapeutic response in mice with established MDR malaria infection and all mice were cured at the determined doses. The combination did not show toxicity at the doses administered to the Swiss mice. Taken together, our findings suggest that compound 15c is a potential partner with AM for the ACT and could be explored for further development.

Objective: The dopamine D2/3 receptor subtypes (DRD2/3) are the most widely studied neurotransmitter biomarker in research on obesity, but results to date have been inconsistent, have typically involved small samples, and have rarely accounted for subjects' ages despite the large impact of age on DRD2/3 levels. We aimed to clarify the relation between DRD2/3 availability and BMI by examining this association in a large sample of subjects with BMI spanning the continuum from underweight to extremely obese., Subjects: 130 healthy subjects between 18 and 81years old underwent PET with [18F]fallypride, a high affinity DRD2/3 ligand., Results: As expected, DRD2/3 availability declined with age. Critically, age significantly interacted with DRD2/3 availability in predicting BMI in the midbrain and striatal regions (caudate, putamen, and ventral striatum). Among subjects under 30years old, BMI was not associated with DRD2/3 availability. By contrast, among subjects over 30years old, BMI was positively associated with DRD2/3 availability in the midbrain, putamen, and ventral striatum., Conclusion: The present results are incompatible with the prominent dopaminergic hypofunction hypothesis that proposes that a reduction in DRD2/3 availability is associated with increased BMI, and highlights the importance of age in assessing correlates of DRD2/3 function., (Copyright © 2016 Elsevier Inc. All rights reserved.)

We quantified the contribution of GLP-1 as a mediator of the therapeutic effects of dipeptidyl peptidase 4 (DPP-4) inhibition (vildagliptin) by using the GLP-1 receptor antagonist exendin [9-39] in patients with type 2 diabetes and in healthy subjects. Thirty-two patients with type 2 diabetes and 29 age- and weight-matched healthy control subjects were treated in randomized order with 100 mg once daily vildagliptin or placebo for 10 days. Meal tests were performed (days 9 and 10) without and with a high-dose intravenous infusion of exendin [9-39]. The main end point was the ratio of the areas under the curve (AUCs) of integrated insulin secretion rates (total AUCISR) and glucose (total AUCglucose) over 4 h after the meal. Vildagliptin treatment more than doubled responses of intact GLP-1 and glucose-dependent insulinotropic polypeptide and lowered glucose responses without changing AUCISR/AUCglucose in healthy subjects. Vildagliptin significantly increased this ratio by 10.5% in patients with type 2 diabetes, and exendin [9-39] reduced it (both P < 0.0001). The percentage reduction in the AUCISR/AUCglucose ratio achieved with exendin [9-39] was significantly smaller after vildagliptin treatment than after placebo treatment (P = 0.026) and was equivalent to 47 ± 5% of the increments due to vildagliptin. Thus, other mediators appear to contribute significantly to the therapeutic effects of DPP-4 inhibition., (© 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.)

3-Carboxy-, 3-carbamoyl-, 3-hydroxymethyl, and 3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine-N-oxyl radicals (CxP, CmP, HMP, and MCP, respectively) have been widely used as redox probes in in vivo magnetic resonance studies. Knowledge of the pharmacokinetics of these probes is essential for redox analyses. The apparent partition coefficient (Kp) of these probes at neutral pH was in the order of MCP>HMP>CmP>CxP. After these probes had been injected intravenously, their blood levels decayed in a bi-phasic manner, namely, fast decay followed by slow decay. The order of the area under the curve (AUC) was CxP»HMP>MCP≥CmP, which roughly coincided with that of Kp in the opposite direction, except for CmP. Decay in the slow phase largely affected the AUC of these probes. The reduction of these probes contributed to their decay in the slow phase. A two-compartment model analysis of blood levels, cyclic voltammetry, and magnetic resonance imaging provided the following pharmacokinetic information. The distribution of the probes between the central and peripheral compartments rapidly reached an equilibrium. In addition to lipophilicity, reduction potential may also be involved in the rate of in vivo reduction of the probes. Hydrophilic probes, such as CxP and CmP, were predominantly excreted in the urine. MCP was distributed to the peripheral tissues and then rapidly reduced. HMP was unique due to its moderate lipophilicity and slower reduction. Among the probes examined, the liver and kidney appear to be included in the central compartment in the two-compartment model analysis. MCP and HMP were rapidly distributed to the brain., (Copyright © 2016 Elsevier Inc. All rights reserved.)

A pharmacokinetic comparison and conformational stability study of S-oxiracetam (S-ORT) and R-oxiracetam (R-ORT) in beagle dogs was used to investigate the possible mechanism of different effects of two oxiracetam enantiomers through a random crossover design. After drug administration to beagle dogs, blood samples were collected at different time points for pharmacokinetic analysis using the UPLC-ESI-MS/MS method. Parts of plasma samples were used for conformation transformation studies using a normal phase high performance liquid chromatographic (NP HPLC) method. The study showed that oxiracetam enantiomers maintained their original conformation when administered orally to beagle dogs. Concentrations of S-ORT were significantly higher than R-ORT 1.5 and 2 h after administration; the AUC0-∞ of S-ORT after oral administration tended to be higher than that of R-ORT, which showed that the different effects between S-ORT and R-ORT may be partly associated with their distinctive absorption at least.

Unlabelled: The synaptic vesicle glycoprotein 2A (SV2A) is found in secretory vesicles in neurons and endocrine cells. PET with a selective SV2A radiotracer will allow characterization of drugs that modulate SV2A (e.g., antiepileptic drugs) and potentially could be a biomarker of synaptic density (e.g., in neurodegenerative disorders). Here we describe the synthesis and characterization of the SV2A PET radiotracer (11)C-UCB-J ((R)-1-((3-((11)C-methyl-(11)C)pyridin-4-yl)methyl)-4-(3,4,5-trifluorophenyl)pyrrolidin-2-one) in nonhuman primates, including whole-body biodistribution., Methods: (11)C-UCB-J was prepared by C-(11)C-methylation of the 3-pyridyl trifluoroborate precursor with (11)C-methyl iodide via the Suzuki-Miyaura cross-coupling method. Rhesus macaques underwent multiple scans including coinjection with unlabeled UCB-J (17, 50, and 150 μg/kg) or preblocking with the antiepileptic drug levetiracetam at 10 and 30 mg/kg. Scans were acquired for 2 h with arterial sampling and metabolite analysis to measure the input function. Regional volume of distribution (VT) was estimated using the 1-tissue-compartment model. Target occupancy was assessed using the occupancy plot; the dissociation constant (Kd) was determined by fitting self-blocking occupancies to a 1-site model, and the maximum number of receptor binding sites (Bmax) values were derived from baseline VT and from the estimated Kd and the nondisplaceable distribution volume (VND)., Results: (11)C-UCB-J was synthesized with greater than 98% purity. (11)C-UCB-J exhibited high free fraction (0.46 ± 0.02) and metabolized at a moderate rate (39% ± 5% and 24% ± 3% parent remaining at 30 and 90 min) in plasma. In the monkey brain, (11)C-UCB-J displayed high uptake and fast kinetics. VT was high (∼25-55 mL/cm(3)) in all gray matter regions, consistent with the ubiquitous expression of SV2A. Preblocking with 10 and 30 mg/kg of levetiracetam resulted in approximately 60% and 90% occupancy, respectively. Analysis of the self-blocking scans yielded a Kd estimate of 3.4 nM and Bmax of 125-350 nM, in good agreement with the in vitro inhibition constant (Ki) of 6.3 nM and regional Bmax in humans. Whole-body biodistribution revealed that the liver and the brain are the dose-limiting organs for males and females, respectively., Conclusion: (11)C-UCB-J exhibited excellent characteristics as an SV2A PET radiotracer in nonhuman primates. The radiotracer is currently undergoing first-in-human evaluation., (© 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.)

TAS-102, a novel oral antitumor agent, consists of trifluridine and tipiracil hydrochloride (molar ratio, 1:0.5). We investigated the effects of food on trifluridine and tipiracil hydrochloride. The efficacy and safety of TAS-102 were evaluated in patients with advanced solid tumors. We analyzed drug pharmacokinetics using a randomized, single-dose, two-treatment (fed versus fasting), two-period, two-sequence cross-over design, followed by repeated administration. Patients were given single doses of TAS-102 (35 mg/m(2) ) in the pharmacokinetic phase and received twice-daily doses of TAS-102 in 28-day cycles in the repeated administration phase for evaluating efficacy and safety. Food showed no effect on the area under the curve from 0 to 12 h or 0 h-infinity values of trifluridine following administration of TAS-102 under fasting and fed conditions, whereas those of tipiracil hydrochloride decreased by approximately 40%. Maximum concentrations of both drugs decreased by approximately 40%, indicating that food influenced the absorption and bioavailability of trifluridine and tipiracil hydrochloride, respectively. During the repeated administration, stable disease was observed in nine patients with rectal, small-cell lung, breast, thymic, duodenal, and prostate cancers. Major adverse events were neutropenia, leukopenia, anemia, and nausea. Postprandial administration was optimal for TAS-102 because trifluridine's area under the curve was not changed by food, indicating that its clinical efficacy would not be affected. Additionally, postprandial administration was reasonable because the maximum concentration of trifluridine decreased in neutrophils, which correlated with previous studies. These results suggest that TAS-102 would be an effective treatment for small-cell lung, thymic, and colorectal cancers. This trial is registered with the Japan Pharmaceutical Information Center (no. JapicCTI-111482)., (© 2016 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)