Clinical Importance of Plasma Drug Concentration of Oral Molecular Targeted Drugs for Renal Cell Carcinoma.

PURPOSE: Therapeutic drug monitoring (TDM) is widely used in clinical practice to maximize drug efficacy and minimize toxicities. Currently, it is also practiced in the use of oral molecular targeted drugs. The objective of this study was to assess the clinical importance of measuring the systemic concentration of oral molecular targeted drugs used to treat renal cell carcinoma (RCC). METHODS: The systemic concentrations of the oral molecular targeted drugs sorafenib, sunitinib, axitinib, pazopanib, and everolimus used for RCC were useful for therapeutic interventions, and clinical outcomes were evaluated retrospectively. RESULTS: The interventional use of systemic drug concentration was confirmed in 26 of 87, and their categories are presented. The systemic concentration of sunitinib was useful in dose reduction and/or discontinuation (n = 10), dose escalation (n = 3), and adherence monitoring (n = 2). Nine of the 10 patients whose dose was reduced showed reduced adverse event. Two patients who were intervened in adherence monitor showed improved adherence. For axitinib, dose reduction and/or discontinuation (n = 1) and dose escalation (n = 6) were confirmed. For pazopanib, dose reduction and/or discontinuation (n = 1) and drug interaction detection (n = 1) were confirmed, both of them were confirmed to have reduced adverse events. For everolimus, dose reduction and/or discontinuation (n = 1) and drug interaction detection (n = 1) were confirmed, a patient with reduced dose recovered from adverse events. Interventions for sorafenib were not identified. CONCLUSIONS: This study demonstrated that systemic concentrations of oral molecular targeted drugs for RCC were considered to be clinically useful for dose adjustment, monitoring of treatment adherence, and the detection of drug interactions. Moreover, this information could be successfully used to guide individualized therapy to maximize the antitumor effects of these drugs.

Pharmacokinetics and safety of niraparib in patients with moderate hepatic impairment.

PURPOSE: The purpose of this study is to characterize niraparib pharmacokinetics (PK) and safety in patients with normal hepatic function (NHF) versus moderate hepatic impairment (MHI). METHODS: Patients with advanced solid tumors were stratified by NHF or MHI (National Cancer Institute-Organ Dysfunction Working Group criteria [bilirubin > 1.5-3 × upper limit of normal and any aspartate aminotransferase elevation]). In the PK phase, all patients received one 300 mg dose of niraparib. In the extension phase, patients with MHI received niraparib 200 mg daily; patients with NHF received 200 or 300 mg based on weight (< 77 kg, ≥ 77 kg)/platelets (< 150,000/µL, ≥ 150,000/µL). PK parameters included maximum concentration (Cmax), area under the curve to last measured concentration (AUClast) and extrapolated to infinity (AUCinf). Safety was assessed in both phases. Exposure-response (E-R) modeling was used to predict MHI effects on exposure and safety of niraparib doses ≤ 200 mg or 300/200 mg or 200/100 mg weight/platelet regimens. RESULTS: In the PK phase (NHF, n = 9; MHI, n = 8), mean niraparib Cmax was 7% lower in patients with MHI versus NHF. Mean exposure (AUClast, AUCinf) was increased by 45% and 56%, respectively, in patients with MHI without impacting tolerability. In the extension phase (NHF, n = 8; MHI, n = 7), the overall safety profile was consistent with previous trials. In patients with MHI, E-R modeling predicted niraparib 200 mg reduced Grade ≥ 3 thrombocytopenia incidence, whereas a 200/100 mg regimen yielded exposures below efficacy-associated levels in 15% of patients. CONCLUSION: These findings support adjusting the 300 mg niraparib starting dose to 200 mg QD in patients with MHI. TRIAL REGISTRATION: NCT03359850; registered December 2, 2017.

Characterization of the pharmacokinetics of entrectinib and its active M5 metabolite in healthy volunteers and patients with solid tumors.

BACKGROUND: Entrectinib is an oral, CNS-active, potent inhibitor of tyrosine receptor kinases A/B/C, tyrosine kinase ROS proto-oncogene 1, and anaplastic lymphoma kinase approved for use in patients with solid tumors. We describe 3 clinical studies, including one investigating the single/multiple dose pharmacokinetics of entrectinib in patients and two studies in healthy volunteers investigating the absorption/distribution/metabolism/excretion (ADME) of entrectinib, its relative bioavailability, and effect of food on pharmacokinetics. METHODS: The patient study is open-label with dose-escalation and expansion phases. Volunteers received entrectinib (100-400 mg/m2, and 600-800 mg) once daily with food in continuous 28-day cycles. In the ADME study, volunteers received a single oral dose of [14C]entrectinib 600 mg. In the third study, volunteers received single doses of entrectinib 600 mg as the research and marketed formulations in the fasted state (Part 1), and the marketed formulation in the fed and fasted states (Part 2). Entrectinib and its major active metabolite M5 were assessed in all studies. RESULTS: Entrectinib was absorbed in a dose-dependent manner with maximum concentrations at ~4 h postdose and an elimination half-life of ~20 h. Entrectinib was cleared mainly through metabolism and both entrectinib and metabolites were eliminated mainly in feces (minimal renal excretion). At steady-state, the M5-to-entrectinib AUC ratio was 0.5 (with 600 mg entrectinib research formulation in patients). The research and marketed formulations were bioequivalent and food had no relevant effect on pharmacokinetics. CONCLUSIONS: Entrectinib is well absorbed, with linear PK that is suitable for once-daily dosing, and can be taken with or without food.

Evaluation of Synthetic Cannabinoid Metabolites in Human Blood in the Absence of Parent Compounds: A Stability Assessment.

Synthetic cannabinoids represent a chemically diverse class of novel psychoactive substances (NPS) responsible for large analytical and interpretative challenges for forensic toxicologists. Between 2016 and 2019, the three most prevalent synthetic cannabinoids in the United States were MMB-FUBINACA (FUB-AMB), 5F-MDMB-PINACA (5F-ADB) and 5F-MDMB-PICA, based on results from seized drug and toxicology testing. In 2018, accurate determination of synthetic cannabinoid positivity was brought into question as it was determined that the metabolites of these drug species were present in the absence of parent compounds in forensically relevant blood samples. During this study, the stability of MMB-FUBINACA, 5F-MDMB-PINACA and 5F-MDMB-PICA was evaluated, as well as the characterization of breakdown products. A liquid-liquid extraction method was assessed for recovery of basic parent compounds and acidic metabolites and deemed fit for use in this study. Analysis was performed by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) using a SCIEX TripleTOF® 5600+. All three synthetic cannabinoids were found to be unstable when stored in blood at either room temperature or refrigerated; all analytes were considerably more stable when stored in the freezer. All three synthetic cannabinoids degraded to their respective butanoic acid metabolites: MMB-FUBINACA 3-methylbutanoic acid, 5F-MDMB-PINACA 3,3-dimethylbutanoic acid and 5F-MDMB-PICA 3,3-dimethylbutanoic acid. All three of these metabolites were studied and determined to be stable in blood at all storage conditions. Considering these results, our laboratory continued testing for synthetic cannabinoid metabolites in blood samples and found 83 positives (21%) for only a synthetic cannabinoid metabolite. A case report is presented herein where 5F-MDMB-PINACA 3,3-dimethylbutanoic acid was identified in the absence of 5F-MDMB-PINACA. Forensic toxicologists should be aware of the results of this study as they directly impact analytical consideration for test development and implementation, as well as interpretation of findings.

Development of a High-Throughput Quantification Method for Pazopanib Using Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry and Its Clinical Application in Patients With Soft Tissue Tumors.

BACKGROUND: Pazopanib is widely used to treat renal cell carcinomas and soft tissue tumors in Japan. Pazopanib has significant therapeutic efficacy but it is associated with frequent severe adverse effects. Therapeutic drug monitoring (TDM) may help to prevent adverse effects. A more convenient and rapid pazopanib assay is desirable for the application of TDM in clinical settings. In this study, the authors developed a high-throughput method for quantifying pazopanib in human plasma using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). METHODS: After a simple solid-phase extraction step using a 96-well plate, pazopanib was analyzed by UHPLC-MS/MS in the positive electrospray ionization mode. RESULTS: The novel method fulfilled the requirements of the US Food and Drug Administration and the European Medicines Agency guidelines for assay validation, and the lower limit of quantification was 0.5 mcg/mL. The calibration curves were linear over the concentration range of 0.5-100 mcg/mL. The average recovery rate was 102.0% ± 3.9% (mean ± SD). The precision was below 5.0%, and the accuracy was within 12.0% for all quality control levels. Matrix effect varied between 90.9% and 97.1%. This assay was successfully applied to TDM of pazopanib trough concentrations in 3 patients treated with the drug for soft tissue tumors. CONCLUSIONS: The authors succeeded in developing a novel high-throughput UHPLC-MS/MS method for quantifying pazopanib in human plasma. This method can be applied to TDM of patients receiving pazopanib in clinical settings.

Assessment of synthetic cannabinoid FUB-AMB and its ester hydrolysis metabolite in human liver microsomes and human blood samples using UHPLC-MS/MS.

FUB-AMB, an indazole carboxamide synthetic cannabinoid recreational drug, was one of the compounds most frequently reported to governmental agencies worldwide between 2016 and 2019. It has been implicated in intoxications and fatalities, posing a risk to public health. In the current study, FUB-AMB was incubated with human liver microsomes (HLM) to assess its metabolic fate and stability and to determine if its major ester hydrolysis metabolite (M1) was present in 12 authentic forensic human blood samples from driving under the influence of drug cases and postmortem investigations using UHPLC-MS/MS. FUB-AMB was rapidly metabolized in HLM, generating M1 that was stable through a 120-min incubation period, a finding that indicates a potential long detection window in human biological samples. M1 was identified in all blood samples, and no parent drug was detected. The authors propose that M1 is a reliable marker for inclusion in laboratory blood screens for FUB-AMB; this metabolite may be pharmacologically active like its precursor FUB-AMB. M1 frequently appears in samples in which the parent drug is undetectable and can point to the causative agent. The results suggest that it is imperative that synthetic cannabinoid laboratory assay panels include metabolites, especially known or potential pharmacologically active metabolites, particularly for compounds with short half-lives.

Determination of KD025 (SLx-2119), a Selective ROCK2 Inhibitor, in Rat Plasma by High-Performance Liquid Chromatography-Tandem Mass Spectrometry and its Pharmacokinetic Application.

KD025 (SLx-2119), the first specific Rho-associated protein kinase 2 (ROCK2) inhibitor, is a potential new drug candidate currently undergoing several phase 2 clinical trials for psoriasis, idiopathic pulmonary fibrosis, chronic graft-versus-host disease, and systemic sclerosis. In this study, a bio-analytical method was developed and fully validated for the quantification of KD025 in rat plasma and for application in pharmacokinetic studies. KD025 and GSK429286A (the internal standard) in rat plasma samples were analyzed by high-performance liquid chromatography-tandem mass spectrometry with m/z transition values of 453.10 → 366.10 and 433.00 → 178.00, respectively. The method was fully validated according to the United State Food and Drug Administration guidelines in terms of selectivity, linearity, accuracy, precision, sensitivity, matrix effects, extraction recovery, and stability. The method enabled the quantification of KD025 levels in rat plasma following oral administration of 5 mg/kg KD025 and intravenous administration of 2 mg/kg KD025 to rats, respectively. Our findings suggest that the developed method is practical and reliable for pharmacokinetic studies of KD025 in preclinical animals.

Extraordinary long detection window of a synthetic cannabinoid metabolite in human urine - Potential impact on therapeutic decisions.

Synthetic cannabinoids (SCs) have become established drugs of abuse. They play an increasing role in drug therapy, where abstinence control testing is required. Differentiation between recent drug uptake and uptake in the distant past is important for drug therapy. This study aimed to evaluate the detection window of a metabolite commonly used as a consumption marker for AB-FUBINACA and AMB-FUBINACA (synonym: FUB-AMB) in urine analysis. The acidic hydrolysis metabolite was quantified in urine samples of a drug user by applying a validated analytical method. The concentration profile of the metabolite was correlated with usage data of the subject. Pharmacokinetic properties of AB-FUBINACA were collected by analysis of serum and urine samples from a controlled administration study (single oral ingestion of AB-FUBINACA). Thirteen urine samples were taken without advance notice over 2 years. The metabolite was detected in the first urine sample at 0.77 ng/mg creatinine and subsequently in concentrations ranging from 0.06 to 0.29 ng/mg creatinine. Usage data showed credible abstinence from SCs during this period. The pharmacokinetic properties observed within the controlled self-administration study supported the hypothesis of distribution into deeper compartments and long-lasting elimination (serum concentration-time curve showing biphasic kinetics). An elimination phase of over 1 year after the last drug uptake seems plausible in cases of extensive consumption. To avoid misinterpretation of positive findings, we recommend testing patients with known SC use at the beginning of the abstinence program and to re-test continuously at short time intervals. These data enable the correct interpretation of analytical findings.

Identification and Quantification of 5-Fluoro ADB and the 5-Fluoro ADB Ester Hydrolysis Metabolite in Postmortem Blood Samples by LC-MS/MS.

5-Fluoro ADB, also known as 5-fluoro MDMB-PINACA, is a potent synthetic cannabinoid that is an agonist to the human cannabinoid CB1 and CB2 receptors. Adverse physiological and psychological effects that have resulted in hospitalization and/or death have been associated with 5-Fluoro ADB use. In addition, analytical confirmation of 5-Fluoro ADB use has been reported in both forensic human performance toxicology and postmortem cases. An analytical method for the identification and quantification of 5-fluoro ADB and the 5-fluoro ADB ester hydrolysis metabolite in human blood samples by liquid chromatography-tandem mass spectrometry was created and validated. The linear range of this assay was determined to be 0.01-10 ng/mL for 5-fluoro ADB and 10-500 ng/mL for the 5-fluoro ADB ester hydrolysis metabolite. The method met both precision and accuracy requirements. Endogenous and exogenous interferences were not observed. Ion suppression exceeding 25% was observed for 5-fluoro ADB. However, additional experiments were performed to ensure that the observed suppression did not affect other method validation parameters such as limit of detection and accuracy. Blood samples from 36 postmortem cases were analyzed utilizing this methodology. The average blood concentration of 5-fluoro ADB was 0.29 ng/mL in central blood specimens and 0.05 ng/mL in peripheral blood specimens. The average blood concentration of the 5-fluoro ADB ester hydrolysis metabolite was 49 ng/mL in central blood specimens and 21 ng/mL in peripheral blood specimens. A serum sample was also analyzed and had a serum concentration of 0.12 ng/mL for 5-fluoro ADB and 42 ng/mL for the 5-fluoro ADB ester hydrolysis metabolite. As the concentration of the 5-fluoro ADB ester hydrolysis metabolite was found at a greater concentration than that of 5-fluoro ADB, this metabolite may be a useful marker to monitor in an attempt to confirm 5-fluoro ADB use in toxicological investigations.

Forty-Three Fatalities Involving the Synthetic Cannabinoid, 5-Fluoro-ADB: Forensic Pathology and Toxicology Implications.

Forty-three fatalities involving the potent synthetic cannabinoid, 5-Fluoro-ADB, are summarized. For each case, a description of the terminal event, autopsy findings, cause of death, qualitative identification of 5-Fluoro-ADB and its ester hydrolysis metabolite, 5-Fluoro-ADB metabolite 7, in urine, and the quantitative values obtained in the blood specimens are outlined. Central blood concentrations ranged from 0.010 to 2.2 ng/mL for 5-Fluoro-ADB and 2.0 to 166 ng/mL for 5-Fluoro-ADB metabolite 7. Peripheral blood concentrations ranged from 0.010 to 0.77 ng/mL and 2.0 to 110 ng/mL for 5-Fluoro-ADB and 5-Fluoro-ADB metabolite 7, respectively. The majority of cases resulted in central to peripheral blood concentration ratios greater than 1 for 5-Fluoro-ADB (58%) and 5-Fluoro-ADB metabolite 7 (71%) suggesting that postmortem redistribution occurs to some extent. Combining the increased cardiac weight and/or gastric volume and toxicology data identifying 5-Fluoro-ADB, it is hypothesized that abuse of this substance may precipitate a dysrhythmia and cause sudden death.

An Innovative Approach to Characterize Clinical ADME and Pharmacokinetics of the Inhaled Drug Nemiralisib Using an Intravenous Microtracer Combined with an Inhaled Dose and an Oral Radiolabel Dose in Healthy Male Subjects.

An innovative open-label, crossover clinical study was used to investigate the excretion balance, pharmacokinetics, and metabolism of nemiralisib-an inhaled phosphoinositide 3-kinase delta inhibitor being developed for respiratory diseases. Six healthy men received a single intravenous microtracer of 10 µg [14C]nemiralisib with a concomitant inhaled nonradiolabeled 1000 µg dose followed by an oral 800 µg dose of [14C]nemiralisib 14 days later. Complementary methods including accelerator mass spectrometry allowed characterization of a range of parameters including oral absorption (Fabs), proportion of nemiralisib escaping gut wall metabolism (Fg), hepatic extraction (Eh), fraction of dose absorbed from inhaled dose (Flung), and renal clearance. Intravenous pharmacokinetics of nemiralisib were characterized by low blood clearance (10.0 l/h), long terminal half-life (55 hours), and high volume of distribution at steady state (728 l). Nemiralisib exhibited moderate inhaled and oral bioavailability (38% and 35%) while Flung was 29%. Absorption and first-pass parameters were corrected for blood renal clearance and compared with values without correction. Any swallowed nemiralisib was relatively well absorbed (Fabs, 0.48) with a high fraction escaping gut wall metabolism and low extraction by the liver (Fg and Eh being 0.83 and 0.10, respectively). There were no major human plasma metabolites requiring further qualification in animal studies. Both unchanged nemiralisib and its oxidative/conjugative metabolites were secreted in bile, with nemiralisib likely subject to further metabolism through enterohepatic recirculation. Direct renal clearance and metabolism followed by renal clearance were lesser routes of elimination. SIGNIFICANCE STATEMENT: A number of innovative features have been combined into one small clinical study enabling a comprehensive description of the human pharmacokinetics and metabolism of an inhaled molecule. Design elements included an intravenous 14C tracer administration concomitant with an inhalation dose that enabled derivation of parameters such as fraction absorbed (Fabs), the proportion of drug escaping first-pass extraction through the gut wall and liver (Fg and Fh) and hepatic extraction (Eh). Entero-test bile sampling enabled characterization of biliary elimination pathways.

Fatal intoxication of a regular drug user following N-ethyl-hexedrone and ADB-FUBINACA consumption.

In Hungary, N-ethyl-hexedrone (NEH) was the most frequently seized stimulant designer drug in 2017, while among synthetic cannabinoids ADB-FUBINACA and AB-FUBINACA were the most popular. Symptoms of intoxication by these substances are well known but less is known about the pathology of overdose-related death. NEH-induced fatal intoxication has not been described in the literature and knowledge surrounding the particular circumstances of death could be useful better public education of risk and more adequate treatment of overdose patients. In this report, we characterize the case of a 23-year-old male regular drug user who died a few hours after NEH and ADB-FUBINACA consumption. His medical history showed arrhythmia in childhood, and some seizures. Autopsy found he had a BMI of 42.9, a hypertrophic and dilated heart, severe atherosclerosis of the valves, coronaries and the arteries, and edema of the internal organs. Histology confirmed those findings. Postmortem blood levels of NEH were 285 ng/ml, along with 0.08 ng/ml ADB-FUBINACA and five ADB-FUBINACA metabolites. Based on the blood concentrations measured in suspected drug users (≤83.9 ng/ml) we hypothesize that NEH intoxication was the cause of death in this case, with heart disease being a co-factor and that the synthetic cannabinoid effect might have been accompaniment. This case also offered the opportunity to identify the metabolites of ADB-FUBINACA in the blood. We identified metabolites in the post-mortem blood by comparing them to human liver microsomal enzyme metabolites in vitro. Three major and two minor metabolites were found in the blood, of which two could only be derived from ADB-FUBINACA, as opposed to other cannabinoids. The case highlights the importance of the complex analysis of drug related deaths by medico-legal autopsy, histopathology and toxicology.

Safety, Tolerability, and Pharmacokinetics of a New Formulation of Nemiralisib Administered via a Dry Powder Inhaler to Healthy Individuals.

PURPOSE: Nemiralisib, a phosphoinositide 3-kinase δ inhibitor, is being investigated as an immunomodulatory agent with anti-inflammatory properties in chronic obstructive pulmonary disease. This study evaluated the pharmacokinetic (PK) properties and safety of a new formulation of nemiralisib that contains 0.4% magnesium stearate. METHODS: In this randomized, double-blind, parallel-group study, healthy individuals received a single dose of 500 or 750 µg of nemiralisib administered via the Ellipta dry powder inhaler (DPI) (n = 6 in each treatment group). Aerodynamic particle size distribution (APSD) data comparing previous and new formulations were available before the study. Serial PK analyses for plasma exposure and safety assessments were performed during the first 24 h after dosing, with follow-up measurements on days 3 and 6 in clinic. FINDINGS: APSD had increases of approximately 6-fold and 2-fold in very fine particle mass and fine particle mass over the previous (Diskus) formulation. In humans, systemic exposure (AUC) was greater after inhalation of 750 versus 500 µg of nemiralisib (AUC0-t: 17,200 h∙pg/mL; 95% CI, 10,900-27,200 h∙pg/mL and 13,100; 95% CI, 8130-21,000 h∙pg/mL, respectively). A low frequency of individual adverse events and no serious adverse events were reported after both doses. IMPLICATIONS: After single-dose inhalation of 500 and 750 µg of nemiralisib from the Ellipta DPI in healthy individuals, plasma PK data were well defined, and as predicted based on previous PK and APSD data, exposure was increased with the new formulation. Nemiralisib was well tolerated with no new safety issues identified. These data supported progression of nemiralisib to a Phase IIb study in patients with chronic obstructive pulmonary disease. ClinicalTrials.gov identifier: NCT03189589.

Relationship between Pharmacokinetics and Pharmacodynamic Responses in Healthy Smokers Informs a Once-Daily Dosing Regimen for Nemiralisib.

Nemiralisib (GSK2269557), a potent inhaled inhibitor of phosphoinositide 3-kinase δ (PI3Kδ), is being developed for the treatment of respiratory disorders including chronic obstructive pulmonary disease. Determining the pharmacokinetic (PK) and pharmacodynamic (PD) responses of inhaled drugs early during drug development is key to informing the appropriate dose and preferred dose regimen in patients. We set out to measure PD changes in induced sputum in combination with drug concentrations in plasma and bronchoalveolar lavage (BAL) taken from healthy smokers (n = 56) treated for up to 14 days with increasing doses of inhaled nemiralisib (0.1-6.4 mg). Induced sputum analysis demonstrated a dose-dependent reduction in phosphatidylinositol-(4,5)-trisphosphate (PIP3, the product of PI3K activation), with a maximum placebo-corrected reduction of 23% (90% confidence interval [CI], 11%-34%) and 36% (90% CI, 11%-64%) after a single dose or after 14 days of treatment with nemiralisib, respectively (2 mg, once daily). Plasma analysis suggested a linear PK relationship with an observed accumulation of ∼3- to 4.5-fold (peak vs. trough) in plasma exposure after 14 days of nemiralisib treatment. The BAL analysis at trough confirmed higher levels of the drug in the lungs versus plasma (32-fold in the BAL fluid component, and 214-fold in the BAL cellular fraction). A comparison of the drug levels in plasma and the reductions in sputum PIP3 showed a direct relationship between exposure and PIP3 reduction. These results demonstrated target engagement upon treatment with inhaled nemiralisib and provide confidence for a once-daily dosing regimen.

A case of 5F-ADB / FUB-AMB abuse: Drug-induced or drug-related death?

Synthetic cannabinoids (SCs) belong to the group of new psychoactive substances (NPS) which appear sprayed on herbal mixtures on the "street" drug market and are intended for smoking like marijuana. In the present report we discuss a fatal case of 18-years-old boy, who had smoked SCs since several months and an overuse of SCs during last 48 h of his life has been apprised. The autopsy findings revealed acute respiratory distress syndrome (ARDS). Both toxicological analysis of deceased blood and urine samples and chemical analysis of the herbal mixture seized revealed presence of two SCs - 5F-ADB and FUB-AMB. The amount of 5F-ADB in blood was found to be 3.7 ng/mL by standard addition method. Severe and irreversible morphology changes in lung specimen, leading to ischemic damage of all internal organs and tissues, were observed during histological examination. The present case can be discussed as an example of both drug-induced and drug-related death resulting from acute intoxication with 5F-ADB and FUB-AMB as well as from systematic use of both synthetic cannabinoids.

In vitro and in vivo pharmacokinetics and metabolism of MK-8353 by liquid chromatography combined with diode array detector and Q-Exactive-Orbitrap tandem mass spectrometry.

In this study, a simple and sensitive quantitation method based on liquid chromatography combined with diode array detector and Q-Exactive-Orbitrap tandem mass spectrometry was developed for the determination of MK-8353 in rat plasma. The chromatographic separation was carried out on a Waters ACQUITY BEH C18 column by using water containing 1 mM ammonium acetate and acetonitrile containing 0.1% formic acid as mobile phase. The developed assay was linear (r > 0.999) over the concentration range of 1-1000 ng/mL. The selectivity, precision, accuracy, recovery, matrix effects and stability were all within the required limits. The validated assay has been further applied to the pharmacokinetic study of MK-8353 in rat after intravenous and oral administration, which revealed that MK-8353 showed low clearance and satisfactory bioavailability. More importantly, the metabolites of MK-8353 present in rat plasma, RLM, DLM and HLM were identified and profiled. Under the current conditions, a total of 10 metabolites were detected and their chemical structures were proposed in terms of the accurate masses and their fragment ions. Our results revealed that MK-8353 was metabolized mainly through dealkylation, demethylation, depropylation, oxygenation, sulfur oxidation and formation of lactam. Compared with animal species, no human-specific metabolite was found in HLM. This study provides overall in vitro and in vivo profiles of MK-8353, which is of great help in understanding its PK/PD profiles and in predicting human pharmacokinetic profiles.

Radiosynthesis and Preclinical Evaluation of an α2A-Adrenoceptor Tracer Candidate, 6-[18F]Fluoro-marsanidine.

PURPOSE: The α2-adrenoceptors mediate many effects of norepinephrine and epinephrine, and participate in the regulation of neuronal, endocrine, cardiovascular, vegetative, and metabolic functions. Of the three receptor subtypes, only α2A and α2C are found in the brain in significant amounts. Subtype-selective positron emission tomography (PET) imaging of α2-adrenoceptors has been limited to the α2C subtype. Here, we report the synthesis of 6-[18F]fluoro-marsanidine, a subtype-selective PET tracer candidate for α2A-adrenoceptors, and its preclinical evaluation in rats and mice. PROCEDURES: 6-[18F]Fluoro-marsanidine was synthesized using electrophilic F-18 fluorination with [18F]Selectfluor bis(triflate). The tracer was evaluated in Sprague Dawley rats and in α2A-knockout (KO) and wild-type (WT) mice for subtype selectivity. In vivo PET imaging and ex vivo brain autoradiography were performed to determine the tracer distribution in the brain. The specificity of the tracer for the target was determined by pretreatment with the subtype-non-selective α2-agonist medetomidine. The peripheral biodistribution and extent of metabolism of 6-[18F]fluoro-marsanidine were also analyzed. RESULTS: 6-[18F]Fluoro-marsanidine was synthesized with [18F]Selectfluor bis(triflate) in a radiochemical yield of 6.4 ± 1.7 %. The molar activity was 3.1 to 26.6 GBq/µmol, and the radiochemical purity was > 99 %. In vivo studies in mice revealed lower uptake in the brains of α2A-KO mice compared to WT mice. The results for selectivity were confirmed by ex vivo brain autoradiography. Blocking studies revealed reduced uptake in α2A-adrenoceptor-rich brain regions in pretreated animals, demonstrating the specificity of the tracer. Metabolite analyses revealed very rapid metabolism of 6-[18F]fluoro-marsanidine with blood-brain barrier-permeable metabolites in both rats and mice. CONCLUSION: 6-[18F]Fluoro-marsanidine was synthesized and evaluated as a PET tracer candidate for brain α2A-adrenoceptors. However, rapid metabolism, extensive presence of labeled metabolites in the brain, and high non-specific uptake in mouse and rat brain make 6-[18F]fluoro-marsanidine unsuitable for α2A-adrenoceptor targeting in rodents in vivo.

Promoting intestinal lymphatic transport targets a liver-X receptor (LXR) agonist (WAY-252,623) to lymphocytes and enhances immunomodulation.

Lymphocytes play a central role in the pathology of a range of chronic conditions such as autoimmune disease, transplant rejection, leukemia, lymphoma HIV/AIDs and cardiometabolic diseases such as atherosclerosis. Current treatments for lymphocyte-associated conditions are incompletely effective and/or complicated by a range of off-target toxicities. One major challenge is poor drug access to lymphocytes via the systemic blood and this may be attributed, at least in part, to the fact that lymphocytes are concentrated within lymph fluid and lymphoid tissues, particularly in gut-associated lymphatics. Here we demonstrate that promoting drug uptake into the intestinal lymphatics with a long chain fatty acid, thereby increasing lymphocyte access, enhances the pharmacodynamic effect of a highly lipophilic liver X receptor (LXR) agonist, WAY-252623, that has been suggested as a potential treatment for atherosclerosis. This has been exemplified by: (1) increased mRNA expression of key markers of LXR activation (ABCA1) and regulatory T cells (Foxp3) in local lymphatic lymphocytes and (2) enhanced numbers of CD4+CD25+Foxp3+ regulatory T cells in the systemic circulation, after administration of a 5-fold lower dose with a lymph directing lipid formulation when compared with a non-lipid containing formulation. These data suggest that combining lipophilic, lymphotropic drug candidates such as WAY-252,623, with lymph-directing long chain lipid based formulations can enhance drug targeting to, and activity on, lymphocytes in lymph and that this effect persists through to the systemic circulation. This presents a promising approach to achieve more selective and effective therapeutic outcomes for the treatment of lymphocyte associated diseases.

Identifying the need to refine the potential patient risk factors for niraparib-induced thrombocytopenia.

OBJECTIVE: Niraparib is a poly (ADP-ribose) polymerase inhibitor (PARP) approved for use in maintenance therapy for ovarian cancer that is associated with the unpredictable grade 3/4 thrombocytopenia. This study was conducted to refine patient dosing recommendations for niraparib based upon clinical practice observations of grade 3/4 thrombocytopenia. METHODS AND MATERIALS: Six patient cases were reviewed to identify similarities in patient factors. An in vitro study was conducted using healthy volunteer blood spiked with Niraparib concentrations ranging from 0 ng/mL to 5000 ng/mL. Manual platelet counts were evaluated at different time intervals for each concentration and compared to untreated controls. Data was then analyzed based on percent change in platelet count versus untreated control for each concentration/time point. RESULTS: In three patients with body weight > 80 kg and platelet count >200 × 109/L, decreased creatinine clearance (CrCl) <60 mL/min was identified as potential signal. An additional three patients with weights below 77 kg and/or baseline platelet counts <150 × 109/L were re-evaluated, and it was observed that all had decreased CrCl of <60 mL/min. Albumin <3.5 g/dL was also observed in some patients with thrombocytopenia. The in vitro study, observed a direct concentration-dependent relationship between niraparib and thrombocytopenia. CONCLUSION: The data suggests that renal insufficiency and hypoalbuminemia may be associated with the development of niraparib-induced thrombocytopenia. Moreover, the preliminary in vitro studies also demonstrated a concentration-dependent relationship between niraparib and direct toxicity to platelets.