CNS Drug Development Research Articles

Application of a new MDCKII-MDR1 cell model to measure the extent of drug distribution in vitro at equilibrium for prediction of in vivo unbound brain-to-plasma drug distribution

Intro: Reliable estimates of drug uptake from blood to brain parenchyma are crucial in CNS drug discovery and development. While in vivo Kp,uu,brain estimates are the gold standard for investigating brain drug disposition, animal usage is a limitation to high throughput application. This study investigates an in vitro model using P-gp expressing MDCKII-MDR1 cells for predicting in vivo brain drug penetration. Methods: In vitro equilibrium distribution studies were conducted in apical and basolateral solutions with high protein content to estimate Kp,brain and Kp,uu,brain values. The correlation between in vitro and in vivo Kp,brain values for a set of compounds was examined. Results: We observed a good correlation between in vitro and in vivo Kp,brain values (R2 = 0.69, Slope: 1.6), indicating that the in vitro model could predict in vivo drug brain penetration. The ‘unilateral (Uni-L)’ in vitro setup correctly classified 5 out of 5 unrestricted compounds and 3 out of 5 restricted compounds. Possible reasons for the observed disparities for some compounds have been discussed, such as difference in transport areas between in vitro and in vivo settings and effect of pH changes. Conclusion: The in vitro assay setup developed in this study holds promise for predicting in vivo drug brain penetration in CNS drug discovery. The correlation between in vitro and in vivo Kp,brain values, underscores that the model may have potential for early-stage screening. With minor refinements, this in vitro approach could reduce the reliance on in vivo experiments, accelerating the pace of CNS drug discovery and promoting a more ethical research approach.

Discovery of novel coumarin triazolyl and phenoxyphenyl triazolyl derivatives targeting amyloid beta aggregation-mediated oxidative stress and neuroinflammation for enhanced neuroprotection.

This study involved designing, synthesizing, and evaluating the protective potential of compounds on microglial cells (BV-2 cells) and neurons (SH-SY5Y cells) against cell death induced by Aβ1-42. It aimed to identify biologically specific activities associated with anti-Aβ aggregation and understand their role in oxidative stress initiation and modulation of proinflammatory cytokine expression. Actively designed compounds CE5, CA5, PE5, and PA5 showed protective effects on BV-2 and SH-SY5Y cells, with cell viability ranging from 60.78 ± 2.32% to 75.38 ± 2.75% for BV-2 cells and 87.21% ± 1.76% to 91.55% ± 1.78% for SH-SY5Y cells. The transformation from ester in CE5 to amide in CA5 resulted in significant antioxidant properties. Molecular docking studies revealed strong binding of CE5 to critical Aβ aggregation regions, disrupting both intra- and intermolecular formations. TEM assessment supported CE5's anti-Aβ aggregation efficacy. Structural variations in PE5 and PA5 had diverse effects on IL-1β and IL-6, suggesting further specificity studies for Alzheimer's disease. Log P values suggested potential blood-brain barrier permeation for CE5 and CA5, indicating suitability for CNS drug development. In silico ADMET and toxicological screening revealed that CE5, PA5, and PE5 have favorable safety profiles, while CA5 shows a propensity for hepatotoxicity. According to this prediction, coumarin triazolyl derivatives are likely to exhibit mutagenicity. Nevertheless, CE5 and CA5 emerge as promising lead compounds for Alzheimer's therapeutic intervention, with further insights expected from subsequent in vivo studies.

Click-train evoked steady state harmonic response as a novel pharmacodynamic biomarker of cortical oscillatory synchrony

Sensory networks naturally entrain to rhythmic stimuli like a click train delivered at a particular frequency. Such synchronization is integral to information processing, can be measured by electroencephalography (EEG) and is an accessible index of neural network function. Click trains evoke neural entrainment not only at the driving frequency (F), referred to as the auditory steady state response (ASSR), but also at its higher multiples called the steady state harmonic response (SSHR). Since harmonics play an important and non-redundant role in acoustic information processing, we hypothesized that SSHR may differ from ASSR in presentation and pharmacological sensitivity. In female SD rats, a 2 s-long train stimulus was used to evoke ASSR at 20 Hz and its SSHR at 40, 60 and 80 Hz, recorded from a prefrontal epidural electrode. Narrow band evoked responses were evident at all frequencies; signal power was strongest at 20 Hz while phase synchrony was strongest at 80 Hz. SSHR at 40 Hz took the longest time (∼180 ms from stimulus onset) to establish synchrony. The NMDA antagonist MK801 (0.025–0.1 mg/kg) did not consistently affect 20 Hz ASSR phase synchrony but robustly and dose-dependently attenuated synchrony of all SSHR. Evoked power was attenuated by MK801 at 20 Hz ASSR and 40 Hz SSHR only. Thus, presentation as well as pharmacological sensitivity distinguished SSHR from ASSR, making them non-redundant markers of cortical network function. SSHR is a novel and promising translational biomarker of cortical oscillatory dynamics that may have important applications in CNS drug development and personalized medicine.

Natural‐Language Processing (NLP) based feature extraction technique in Deep‐Learning model to predict the Blood‐Brain‐Barrier permeability of molecules

AbstractBlood‐Brain‐Barrier (BBB) permeability is one of the critical factors in the success and failure of CNS drug development. The most accurate method of measuring BBB permeability involves clinical experiments, which are labour‐intensive and time‐consuming. Thus, numerous efforts were made to use artificial intelligence (AI) to predict molecules′ BBB permeability. Most of the previous models are based on calculated descriptors and molecular fingerprints. In the present work, we have developed an NLP‐based feature extraction technique in Deep‐Learning models to predict BBB permeability. We have used the B3DB database and generated SELFIES to extract features from the molecules. We have employed word level and N‐gram tokenization to represent words into numeric vectors. The extracted features were fed into several Artificial Neural Network (ANN) and Bi‐directional Long Short‐Term Memory (LSTM) models. The model, ANN‐10 built using ANN and 6‐gram tokenization, performed best on the independent test set. The accuracy, precision, recall, F1, specificity and AUC of ROC scores were found to be 0.89, 0.91, 0.91, 0.91, 0.85 and 0.90. Thus, the developed model can be used for the early screening of CNS drugs.

Recent update on pharmacokinetics and drug metabolism in CNS-based drug discovery.

Despite significant advancements in CNS research, CNS illnesses are the most important and serious cause of mental disability worldwide. These facts show a tremendous unmet demand for effective CNS medications and pharmacotherapy since it accounts for more hospitalizations and extended care than practically all other disorders combined. The site-targeted kinetics of the brain and, pharmacodynamics of CNS effects are determined/regulated by various mechanisms after the dose, including blood-brain barrier (BBB) transport and many other processes. These processes are condition-dependent in terms of their rate and extent because they are dynamically controlled. For effective therapy, drugs should access the CNS "at the right place, time, and concentration". Details on inter-species and inter-condition variances are required to translate target site pharmacokinetics and associated CNS effects between species and illness states, improving CNS therapeutics and drug development. The present review encircles a short discussion about the barriers that affect effective CNS treatment and precisely focuses on the pharmacokinetics aspects of efficient CNS therapeutics.

Drugs in the Developmental Stage (Psychotropics)

In recent years, it is common for a single drug to be developed for multiple diseases almost simultaneously, e.g., pimavanserin and psilocybin. Although there was gloomy news for the field of neuropsychopharmacology, such as withdrawal of the world's leading mega-pharmaceutical companies from the development of CNS drugs, drugs based on novel mechanisms of action have been investigated. This is a new dawn in the field of clinical psychopharmacology.

Construction and Functional Evaluation of a Three-Dimensional Blood–Brain Barrier Model Equipped With Human Induced Pluripotent Stem Cell-Derived Brain Microvascular Endothelial Cells

PurposeThe purpose of this study was to construct and validate an in vitro three-dimensional blood–brain barrier (3DBBB) model system equipped with brain microvascular endothelial cells derived from human induced pluripotent stem cells (hiPS-BMECs).MethodsThe 3D-BBB system was constructed by seeding hiPS-BMECs onto the capillary lane of a MIMETAS OrganoPlate® 3-lane coated with fibronectin/collagen IV. hiPS-BMECs were incubated under continuous switchback flow with an OrganoFlow® for 2 days. The 3D capillary structure and expression of tight-junction proteins and transporters were confirmed by immunocytochemistry. The mRNA expression of transporters in the 3D environment was determined using qRT-PCR, and the permeability of endogenous substances and drugs was evaluated under various conditions.Results and DiscussionThe expression of tight-junction proteins, including claudin-5 and ZO-1, was confirmed by immunohistochemistry. The permeability rate constant of lucifer yellow through hiPS-BMECs was undetectably low, indicating that paracellular transport is highly restricted by tight junctions in the 3D-BBB system. The mRNA expression levels of transporters and receptors in the 3D-BBB system differed from those in the 2D-culture system by 0.2- to 5.8-fold. The 3D-cultured hiPS-BMECs showed asymmetric transport of substrates of BCRP, CAT1 and LAT1 between the luminal (blood) and abluminal (brain) sides. Proton-coupled symport function of MCT1 was also confirmed.ConclusionThe 3D-BBB system constructed in this study mimics several important characteristics of the human BBB, and is expected to be a useful high-throughput evaluation tool in the development of CNS drugs.

Positioning psychiatric pharmacists to improve mental health care

Psychiatric pharmacy continues to grow and look to the future with a focus on helping individuals recover from mental health and substance use disorders. The American Association of Psychiatric Pharmacists (AAPP) considers Board Certified Psychiatric Pharmacist (BCPP) the gold standard credential that all psychiatric pharmacists should attain to demonstrate specialized knowledge and expertise in psychiatry. BCPPs are part of collaborative interprofessional teams and practice in hospitals, clinics, and diverse health systems. Two out of 3 BCPPs practicing in clinics have prescriptive authority. BCPPs improve access, safety, medication adherence, and therapeutic outcomes. Every person with a mental health and substance use disorder should have access to a BCPP providing comprehensive medication management (CMM) and psychotropic stewardship aimed at improving population health. BCPPs are in demand owing to their expertise. AAPP envisions growth and expansion of the BCPP role in many areas including coordinating psychiatric transitions of care and telehealth services, managing long-acting injectable medication clinics, providing pharmacogenomic consultation, conducting clozapine and lithium monitoring, managing medications for substance use disorders, leading medication groups, CNS drug development, research, and provider education. To prepare the workforce, colleges and schools of pharmacy should hire BCPPs for optimal curriculum development, and each student pharmacist should have an opportunity to develop a therapeutic alliance with a person recovering from psychiatric illness. Postgraduate year (PGY) 1 residencies should offer learning experiences in psychiatric pharmacy to prepare residents to enter an expanded number of PGY2 psychiatric pharmacy residencies, ultimately earning their BCPP and being well positioned to improve mental health care.

Mismatch negativity as EEG biomarker supporting CNS drug development: a transnosographic and translational study

The lack of translation from basic research into new medicines is a major challenge in CNS drug development. The need to use novel approaches relying on (i) patient clustering based on neurobiology irrespective to symptomatology and (ii) quantitative biomarkers focusing on evolutionarily preserved neurobiological systems allowing back-translation from clinical to nonclinical research has been highlighted. Here we sought to evaluate the mismatch negativity (MMN) response in schizophrenic (SZ) patients, Alzheimer’s disease (AD) patients, and age-matched healthy controls. To evaluate back-translation of the MMN response, we developed EEG-based procedures allowing the measurement of MMN-like responses in a rat model of schizophrenia and a mouse model of AD. Our results indicate a significant MMN attenuation in SZ but not in AD patients. Consistently with the clinical findings, we observed a significant attenuation of deviance detection (~104.7%) in rats subchronically exposed to phencyclidine, while no change was observed in APP/PS1 transgenic mice when compared to wild type. This study provides new insight into the cross-disease evaluation of the MMN response. Our findings suggest further investigations to support the identification of neurobehavioral subtypes that may help patients clustering for precision medicine intervention. Furthermore, we provide evidence that MMN could be used as a quantitative/objective efficacy biomarker during both preclinical and clinical stages of SZ drug development.

A review: Brain specific delivery

The overall prevalence rate for CNS pathology has demonstrated that approximately more than one billion people are undergoing from disorders of central nervous system. The most distressing fact about delivery of drugs to the CNS is the presence of blood brain barrier that have a tendency to impair the drug distribution and denotes the major impediment for the development of CNS drugs. Neuropeptides and many drugs which are hydrophilic in nature possibly will encompass the intricacy while passing the blood brain barrier. The net amount of delivered drug (medicinal agent) and its capability to gain access to the pertinent target sites are the main considering points for CNS drug development. Brain targeted drug delivery to the brain is valuable in the diseases of brain. (Alzheimer’s diseases, meningitis, brain abscess, epilepsy, multiple sclerosis, neuromylitis optica, sleeping disorders etc). Whereby high concentration can be gained with lesser side effects that occur because of release of drugs. The simplest method of targeting to brain is to obtain a therapeutic. Brain targeting systems to remain in the brain region by crossing BBB and hence significantly helps in increasing therapeutic activity. There is an increasing attraction towards brain targeting and sue to its immense application in the treatment of various CNS diseases because mostly drugs are unable to cross the BBB. This review article discuss one of the novel technology “nanotechnology” and other aspects that has been developed to target the brain and possess various clinical benefits such as reduced drug dose, less side effects, non-invasive routed, and better patient compliance.

Placebo response mitigation with a participant-focused psychoeducational procedure: a randomized, single-blind, all placebo study in major depressive and psychotic disorders

The remarkably high and growing placebo response rates in clinical trials for CNS indications, such as depression and schizophrenia, constitute a major challenge for the drug development enterprise. Despite extensive literature on participant expectancies and other potent psychosocial factors that perpetuate placebo response, no empirically validated participant-focused strategies to mitigate this phenomenon have been available. This study evaluated the efficacy of the Placebo-Control Reminder Script (PCRS), a brief interactive procedure that educates participants about factors known to cause placebo response, which was administered prior to the primary outcome assessments to subjects with major depressive or psychotic disorders who had at least moderate depression. Participants were informed they would participate in a 2-week randomized clinical trial with a 50% chance of receiving either an experimental antidepressant medication or placebo. In actuality, all participants received placebo. Participants randomly assigned to receive the PCRS (n = 70) reported significantly smaller reductions (i.e., less placebo response) in depression than those who did not receive the PCRS (n = 67). The magnitude of this effect was medium (Cohen’s d = 0.40) and was not significantly impacted by diagnostic status. The number of adverse events (i.e., nocebo effect) was also lower in the PCRS group, particularly in the first week of the study. These findings suggest that briefly educating participants about placebo response factors can help mitigate the large placebo response rates that are increasingly seen in failed CNS drug development programs.

Recent progress in translational engineered in vitro models of the central nervous system.

The complexity of the human brain poses a substantial challenge for the development of models of the CNS. Current animal models lack many essential human characteristics (in addition to raising operational challenges and ethical concerns), and conventional in vitro models, in turn, are limited in their capacity to provide information regarding many functional and systemic responses. Indeed, these challenges may underlie the notoriously low success rates of CNS drug development efforts. During the past 5 years, there has been a leap in the complexity and functionality of in vitro systems of the CNS, which have the potential to overcome many of the limitations of traditional model systems. The availability of human-derived induced pluripotent stem cell technology has further increased the translational potential of these systems. Yet, the adoption of state-of-the-art in vitro platforms within the CNS research community is limited. This may be attributable to the high costs or the immaturity of the systems. Nevertheless, the costs of fabrication have decreased, and there are tremendous ongoing efforts to improve the quality of cell differentiation. Herein, we aim to raise awareness of the capabilities and accessibility of advanced in vitro CNS technologies. We provide an overview of some of the main recent developments (since 2015) in in vitro CNS models. In particular, we focus on engineered in vitro models based on cell culture systems combined with microfluidic platforms (e.g. 'organ-on-a-chip' systems). We delve into the fundamental principles underlying these systems and review several applications of these platforms for the study of the CNS in health and disease. Our discussion further addresses the challenges that hinder the implementation of advanced in vitro platforms in personalized medicine or in large-scale industrial settings, and outlines the existing differentiation protocols and industrial cell sources. We conclude by providing practical guidelines for laboratories that are considering adopting organ-on-a-chip technologies.

Drug Delivery Strategies to Overcome the Blood-Brain Barrier (BBB).

The brain capillary endothelium serves both as an exchange site for gases and solutes between blood and brain and as a protective fence against neurotoxic compounds from the blood. While this "blood-brain barrier" (BBB) function protects the fragile environment in the brain, it also poses a tremendous challenge for the delivery of drug compounds to the brain parenchyma. Paracellular brain uptake of drug compounds is limited by the physical tightness of the endothelium, which is tightly sealed with junction complexes. Transcellular uptake of lipophilic drug compounds is limited by the activity of active efflux pumps in the luminal membrane. As a result, the majority of registered CNS drug compounds are small lipophilic compounds which are not efflux transporter substrates. Small molecule CNS drug development therefore focuses on identifying compounds with CNS target affinity and modifies these in order to optimize lipophilicity and decrease efflux pump interactions. Since efflux pump activity is limiting drug uptake, it has been investigated whether coadministration of drug compounds with efflux pump inhibitors could increase drug uptake. While the concept works to some extent, a lot of challenges have been encountered in terms of obtaining efficient inhibition while avoiding adverse effects.Some CNS drug compounds enter the brain via nutrient transport proteins, an example is the levodopa, a prodrug of Dopamine, which crosses the BBB via the large neutral amino acid transporter LAT1. While carrier-mediated transport of drug compounds may seem attractive, the development of drugs targeting transporters is very challenging, since the compounds should have a good fit to the binding site, while still maintaining their CNS target affinity.Receptor-mediated transport of drug compounds, especially biotherapeutics, conjugated to a receptor-binding ligand has shown some promise, although the amounts transported are rather low. This also holds true for drug-conjugation to cell-penetrating peptides. Due to the low uptake of biotherapeutics, barrier-breaching approaches such as mannitol injections and focused ultrasound have been employed with some success to patient groups with no other treatment options.

Brain Distribution of Drugs: Pharmacokinetic Considerations.

It is crucial to understand the basic principles of drug transport, from the site of delivery to the site of action within the CNS, in order to evaluate the possible utility of a new drug candidate for CNS action, or possible CNS side effects of non-CNS targeting drugs. This includes pharmacokinetic aspects of drug concentration-time profiles in plasma and brain, blood-brain barrier transport and drug distribution within the brain parenchyma as well as elimination processes from the brain. Knowledge of anatomical and physiological aspects connected with drug delivery is crucial in this context. The chapter is intended for professionals working in the field of CNS drug development and summarizes key pharmacokinetic principles and state-of-the-art experimental methodologies to assess brain drug disposition. Key parameters, describing the extent of unbound (free) drug across brain barriers, in particular blood-brain and blood-cerebrospinal fluid barriers, are presented along with their application in drug development. Special emphasis is given to brain intracellular pharmacokinetics and its role in evaluating target engagement. Fundamental neuropharmacokinetic differences between small molecular drugs and biologicals are discussed and critical knowledge gaps are outlined.

Advances in CNS drug development

Advances in CNS drug development

Development of a non-human primate model to support CNS translational research: Demonstration with D-amphetamine exposure and dopamine response

BackgroundChallenges specific to the discovery and development of candidate CNS drugs have led to implementation of various in silico, in vitro and in vivo approaches to improve the odds for commercialization of novel treatments. New methodAdvances in analytical methodology and microdialysis probe design have enabled development of a non-human primate model capable of measuring concentrations of drugs or endogenous chemicals in brain extracellular fluid (ECF) and cerebrospinal fluid (CSF). Linking these to population modeling reduces animal numbers to support predictive translational sciences in primates. Application to measure D-amphetamine exposure and dopamine response in ECF and CSF demonstrate the approach. ResultsFollowing a 0.1 mg/kg intravenous bolus dose of D-amphetamine, a population approach was used to build a plasma compartmental-based and brain physiologic-based pharmacokinetic (PK) model linking drug concentrations in plasma to brain ECF and CSF concentrations. Dopamine was also measured in brain ECF. The PK model was used to simulate the relationship between D-amphetamine exposure and dopamine response in ECF over a wide dose range. Comparisons with existing methodsAbility to co-sample and measure drug and endogenous substances in blood, brain ECF and/or CSF, coupled with population modeling, provides an in vivo approach to evaluate CNS drug penetration and effect in non-human primates. ConclusionsA method to measure drug and endogenous neurochemicals in non-human primate brain fluids is demonstrated. Its basis in non-human primates merits improved confidence regarding predictions of drug exposure and target engagement in human CNS.

Development of human immortalized cell-based multicellular spheroidal blood-brain barrier model for CNS drug development studies

Development of human immortalized cell-based multicellular spheroidal blood-brain barrier model for CNS drug development studies

The application of positron emission tomography (PET) imaging in CNS drug development.

As drug discovery and development in Neuroscience push beyond symptom management to disease modification, neuroimaging becomes a key area of translational research that enables measurements of the presence of drugs and downstream physiological consequences of drug action within the living brain. As such, neuroimaging can be used to help optimize decision-making processes throughout the various phases of drug development. Positron Emission Tomography (PET) is a functional imaging technique that allows the quantification and visualization of biochemical processes, by monitoring the time dependent distribution of molecules labelled with short-lived positron-emitting isotopes. This review focuses on the application of PET to support CNS drug development, particularly in the early clinical phases, by allowing us to measure tissue exposure, target engagement, and pharmacological activity. We will also discuss the application of PET imaging as tools to image the pathological hallmarks of disease and evaluate the potential disease-modifying effect of candidate drugs in slowing disease progression.

Differentiated HASTR/ci35 cells: A promising in vitro human astrocyte model for facilitating CNS drug development studies

Astrocytes have shown longstanding promise as therapeutic targets for various central nervous system diseases. To facilitate drug development targeting astrocytes, we have recently developed a new conditionally immortalized human astrocyte cell line, termed HASTR/ci35 cells. In this study, in order to further increase their chances to contribute to various astrocyte studies, we report on the development of a culture method that improves HASTR/ci35 cell differentiation status and provide several proofs related to their astrocyte characteristics. The culture method is based on the simultaneous elimination of serum effects and immortalization signals. The results of qPCR showed that the culture method significantly enhanced several astrocyte marker gene expression levels. Using the differentiated HASTR/ci35, we examined their response profiles to nucleotide treatment and inflammatory stimuli, along with their membrane fatty acid composition. Consequently, we found that they responded to ADP or UTP treatment with a transient increase of intracellular Ca2+ concentration, and that they could show reactive response to interleukin-1β treatments. Furthermore, the membrane phospholipids of the cells were enriched with polyunsaturated fatty acids. To summarize, as a unique human astrocyte model carrying the capability of a differentiation induction properties, HASTR/ci35 cells are expected to contribute substantially to astrocyte-oriented drug development studies.

CNS Drug Development, Lessons Learned, Part 5: How Preclinical and Human Safety Studies Inform the Approval and Subsequent Use of a New Drug-Suvorexant as an Example.

This column is the fifth in a series examining the advances being made in central nervous system drug development because of advances in molecular pharmacology and an improved understanding of the neurobiology underlying disturbances in brain function including psychiatric illnesses. This column covers the special animal and human studies conducted as part of the development of suvorexant, which is the first in the class of dual orexin 1 and 2 receptor antagonists to be approved; it has an indication for the treatment of disturbances in sleep onset and maintenance. The animal studies included determination of the therapeutic index of the drug (ie, lethal dose 50 which is the dose at which 50% of animals die following administration of the drug), adverse effects on fertility, teratogenicity, carcinogenicity, and ability to cause narcolepsy. The human studies included investigation of the effects of the drug on balance, memory, driving performance, and propensity to cause respiratory depression in normal volunteers and individuals with mild to moderate chronic obstructive pulmonary disorder or mild to moderate obstructive sleep apnea. This column illustrates how targeting the drug to one mechanism out of hundreds yields increased safety and highlights the importance of the package insert which summarizes the results of all of the studies from the drug's development program.