Bioanalytical Assessment of Plasma Concentrations of Angiotensin-Converting Enzyme II Inhibitors and Angiotensin Receptor Blockers: A Pilot Study Among Patients Hospitalized With Acute Heart Failure.

BACKGROUND: Although angiotensin-converting enzyme II inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) improve chronic heart failure (HF) outcomes, their potential harms and benefits in acute HF (AHF) is less clear. STUDY QUESTION: We explored the relationship between ACEI or ARB plasma concentrations among patients with AHF with in-hospital change in estimated glomerular filtration rate (eGFR). DATA SOURCES AND STUDY DESIGN: From August 2016-June 2017, patients with AHF prescribed an outpatient ACEI or ARB were enrolled before AHF treatment. All patients were given twice their home dose of diuretic intravenously and received clinical care at the discretion of the medical team. Of 61 patients in the parent study, saved plasma from 34 who were prescribed an outpatient ACEI or ARB was included in this substudy. MEASURES AND OUTCOMES: Liquid chromatography-tandem mass spectrometry was performed to assess ACEI or ARB plasma concentrations before AHF treatment. Change in eGFR was computed using the Chronic Kidney Disease Epidemiology Collaboration equation, which adjusts for age, sex, and race; diuretic dose and enrollment eGFR were used to adjust for HF severity. Multiple linear regression adjusting for enrollment eGFR and diuretic dose was performed to examine the relationship between drug concentration (undetectable/low vs. in/above-range) and in-hospital change in eGFR. RESULTS: Of 34 patients with AHF, median age was 63 years (interquartile range, 58-78 years), 19 (55.9%) were women, median eGFR at enrollment was 55.6 mL/min (interquartile range, 35.2-75.3 mL/min), and for 11 (32.4%), no ACEI or ARB was detectable in plasma. Medication concentrations in- or above-reference range were associated with in-hospital decrease in eGFR of 8.3 mL/min (95% confidence interval, 15.3-1.3 mL/min decrease), after adjusting for enrollment eGFR and diuretic treatment. CONCLUSIONS: Bioanalytical assessment of medication levels may be useful to guide in-hospital ACEI and ARB therapy for patients with AHF.

VU0810464, a non-urea G protein-gated inwardly rectifying K+ (Kir 3/GIRK) channel activator, exhibits enhanced selectivity for neuronal Kir 3 channels and reduces stress-induced hyperthermia in mice.

BACKGROUND AND PURPOSE: G protein-gated inwardly rectifying K+ (Kir 3) channels moderate the activity of excitable cells and have been implicated in neurological disorders and cardiac arrhythmias. Most neuronal Kir 3 channels consist of Kir 3.1 and Kir 3.2 subtypes, while cardiac Kir 3 channels consist of Kir 3.1 and Kir 3.4 subtypes. Previously, we identified a family of urea-containing Kir 3 channel activators, but these molecules exhibit suboptimal pharmacokinetic properties and modest selectivity for Kir 3.1/3.2 relative to Kir 3.1/3.4 channels. Here, we characterize a non-urea activator, VU0810464, which displays nanomolar potency as a Kir 3.1/3.2 activator, improved selectivity for neuronal Kir 3 channels, and improved brain penetration. EXPERIMENTAL APPROACH: We used whole-cell electrophysiology to measure the efficacy and potency of VU0810464 in neurons and the selectivity of VU0810464 for neuronal and cardiac Kir 3 channel subtypes. We tested VU0810464 in vivo in stress-induced hyperthermia and elevated plus maze paradigms. Parallel studies with ML297, the prototypical activator of Kir 3.1-containing Kir 3 channels, were performed to permit direct comparisons. KEY RESULTS: VU0810464 and ML297 exhibited comparable efficacy and potency as neuronal Kir 3 channel activators, but VU0810464 was more selective for neuronal Kir 3 channels. VU0810464, like ML297, reduced stress-induced hyperthermia in a Kir 3-dependent manner in mice. ML297, but not VU0810464, decreased anxiety-related behaviour as assessed with the elevated plus maze test. CONCLUSION AND IMPLICATIONS: VU0810464 represents a new class of Kir 3 channel activator with enhanced selectivity for Kir 3.1/3.2 channels. VU0810464 may be useful for examining Kir 3.1/3.2 channel contributions to complex behaviours and for probing the potential of Kir 3 channel-dependent manipulations to treat neurological disorders.

Inhibition of hepatobiliary transporters by a novel kinase inhibitor contributes to hepatotoxicity in beagle dogs.

PF-022 (1) is a novel polycyclic benzothiophene kinase inhibitor selective for mitogen-activated protein kinase-activated protein kinase 2 (MK2). Compound 1 emerged as an inhibitor bearing submicromolar potency against MK2 (IC50 5 nM) and demonstrated projected human pharmacokinetics sufficient for oral dosing. However, following a single, oral administration of 1 to beagle dogs, animals experienced an acute liver injury characterized by increases in biomarkers associated with hepatotoxicity; particularly noteworthy was the reversible elevation in bile salts and total bilirubin. Accompanying this observation was an ADME appraisal which included hepatic bioactivation of 1 in multiple species and the in vitro inhibition of P-glycoprotein (P-gp; IC50 21 µM). Simply attenuating the bioactivation via structural modification proved ineffective in improving the in vivo tolerability of this polycyclic scaffold. Hence, disruption of hepatobiliary transporters by the compound series was hypothesized as the likely mechanism contributing to the acute hepatotoxicity. Indeed, closer in vitro examination employing transporter gene overexpressing MDCK cell lines and membrane vesicles revealed potent compound-dependent inhibition of human multi-drug resistance-associated protein 2 (MRP2/ABCC2; IC50 38 µM) and bile salt export pump (BSEP/ABCB11; IC50 10 µM), two crucial hepatobiliary transport proteins accountable for bilirubin and bile salt homeostasis, respectively. Subsequent introduction of pKa-altering modifications to a second generation compound PF029 proved successful in reducing its affinity for these key efflux transporters (MRP2 IC50 >>80 µM; BSEP IC50 > 70 µM; P-gp > 90 µM), consequently mitigating this overt organ toxicity in dogs.

Neurovascular unit on a chip: implications for translational applications.

The blood-brain barrier (BBB) dynamically controls exchange between the brain and the body, but this interaction cannot be studied directly in the intact human brain or sufficiently represented by animal models. Most existing in vitro BBB models do not include neurons and glia with other BBB elements and do not adequately predict drug efficacy and toxicity. Under the National Institutes of Health Microtissue Initiative, we are developing a three-dimensional, multicompartment, organotypic microphysiological system representative of a neurovascular unit of the brain. The neurovascular unit system will serve as a model to study interactions between the central nervous system neurons and the cerebral spinal fluid (CSF) compartment, all coupled to a realistic blood-surrogate supply and venous return system that also incorporates circulating immune cells and the choroid plexus. Hence all three critical brain barriers will be recapitulated: blood-brain, brain-CSF, and blood-CSF. Primary and stem cell-derived human cells will interact with a variety of agents to produce critical chemical communications across the BBB and between brain regions. Cytomegalovirus, a common herpesvirus, will be used as an initial model of infections regulated by the BBB. This novel technological platform, which combines innovative microfluidics, cell culture, analytical instruments, bioinformatics, control theory, neuroscience, and drug discovery, will replicate chemical communication, molecular trafficking, and inflammation in the brain. The platform will enable targeted and clinically relevant nutritional and pharmacologic interventions for or prevention of such chronic diseases as obesity and acute injury such as stroke, and will uncover potential adverse effects of drugs. If successful, this project will produce clinically useful technologies and reveal new insights into how the brain receives, modifies, and is affected by drugs, other neurotropic agents, and diseases.