Electroresponsive Nanoparticles Improve Antiseizure Effect of Phenytoin in Generalized Tonic-Clonic Seizures

Biomedical applications of stimuli-responsive nanomaterials

Nanomaterials have aroused great interests in drug delivery due to their nanoscale structure, facile modifiability, and multifunctional physicochemical properties. Currently, stimuli-responsive nanomaterials that can respond to endogenous or exogenous stimulus display strong potentials in biomedical applications. In comparison with conventional nanomaterials, stimuli-responsive nanomaterials can improve therapeutic efficiency and reduce the toxicity of drugs toward normal tissues through specific targeting and on-demand drug release at pathological sites. In this review, we summarize the responsive mechanism of a variety of stimulus, including pH, redox, and enzymes within pathological microenvironment, as well as exogenous stimulus such as thermal effect, magnetic field, light, and ultrasound. After that, biomedical applications (e.g., drug delivery, imaging, and theranostics) of stimuli-responsive nanomaterials in a diverse array of common diseases, including cardiovascular diseases, cancer, neurological disorders, inflammation, and bacterial infection, are presented and discussed. Finally, the remaining challenges and outlooks of future research directions for the biomedical applications of stimuli-responsive nanomaterials are also discussed. We hope that this review can provide valuable guidance for developing stimuli-responsive nanomaterials and accelerate their biomedical applications in diseases diagnosis and treatment.

Antiepileptic drug-loaded and multifunctional iron oxide@silica@gelatin nanoparticles for acid-triggered drug delivery

The current study developed an innovative design for the production of smart multifunctional core-double shell superparamagnetic nanoparticles (NPs) with a focus on the development of a pH-responsive drug delivery system tailored for the controlled release of Phenytoin, accompanied by real-time monitoring capabilities. In this regard, the ultra-small superparamagnetic iron oxide@silica NPs (IO@Si MNPs) were synthesized and then coated with a layer of gelatin containing Phenytoin as an antiepileptic drug. The precise saturation magnetization value for the resultant NPs was established at 26 emu g-1. The polymeric shell showed a pH-sensitive behavior with the capacity to regulate the release of encapsulated drug under neutral pH conditions, simultaneously, releasing more amount of the drug in a simulated tumorous-epileptic acidic condition. The NPs showed an average size of 41.04 nm, which is in the desired size range facilitating entry through the blood-brain barrier. The values of drug loading and encapsulation efficiency were determined to be 2.01 and 10.05%, respectively. Moreover, kinetic studies revealed a Fickian diffusion process of Phenytoin release, and diffusional exponent values based on the Korsmeyer-Peppas equation were achieved at pH 7.4 and pH 6.3. The synthesized NPs did not show any cytotoxicity. Consequently, this new design offers a faster release of PHT at the site of a tumor in response to a change in pH, which is essential to prevent epileptic attacks.

(+)-Borneol enantiomer ameliorates epileptic seizure via decreasing the excitability of glutamatergic transmission

Epilepsy is one common brain disorder, which is not well controlled by current pharmacotherapy. In this study we characterized the therapeutic potential of borneol, a plant-derived bicyclic monoterpene compound, in the treatment of epilepsy and elucidated the underlying mechanisms. The anti-seizure potency and properties of borneol were assessed in both acute and chronic mouse epilepsy models. Administration of (+)-borneol (10, 30, 100 mg/kg, i.p.) dose-dependently attenuated acute epileptic seizure in maximal-electroshock seizure (MES) and pentylenetetrazol (PTZ)-induced seizure models without obvious side-effect on motor function. Meanwhile, (+)-borneol administration retarded kindling-induced epileptogenesis and relieved fully kindled seizures. Importantly, (+)-borneol administration also showed therapeutic potential in kainic acid-induced chronic spontaneous seizure model, which was considered as a drug-resistant model. We compared the anti-seizure efficacy of 3 borneol enantiomers in the acute seizure models, and found (+)-borneol being the most satisfying one with long-term anti-seizure effect. In electrophysiological study conducted in mouse brain slices containing the subiculum region, we revealed that borneol enantiomers displayed different anti-seizure mechanisms, (+)-borneol (10 μM) markedly suppressed the high frequency burst firing of subicular neurons and decreased glutamatergic synaptic transmission. In vivo calcium fiber photometry analysis further verified that administration of (+)-borneol (100 mg/kg) inhibited the enhanced glutamatergic synaptic transmission in epilepsy mice. We conclude that (+)-borneol displays broad-spectrum anti-seizure potential in different experimental models via decreasing the glutamatergic synaptic transmission without obvious side-effect, suggesting (+)-borneol as a promising anti-seizure compound for pharmacotherapy in epilepsy.

Electro-responsive micelle-based universal drug delivery system for on-demand therapy in epilepsy

A universal drug delivery system (DDS) with brain-targeted ability is demanded to enhance antiepileptic therapeutic efficacy and reduce side effects in multiple types of epileptic seizures. In this study, we reported a micelle-based DDS possessing the brain-targeted ability and electro-responsive feature for universal delivery of antiepileptic drugs (AEDs). The system is fabricated by ferrocene (Fc)-conjugated D-a-tocopherol polyethylene glycol succinate and amphiphilic block copolymer, which improve the drug encapsulation of different AEDs. Interestingly, the intrinsic nature of TPGS-Fc including transferrin receptor-mediated transcytosis and efflux pump inhibition endows the system with high permeability across the blood-brain barrier. Based on the hydrophobic-hydrophilic transition of Fc, the micelles can respond to epileptiform discharges and thus release the loaded AEDs. Improved antiepileptic efficacy of the micelles has been demonstrated in acute, continuous, and chronic epilepsy models. In summary, we have developed a universal micelle-based DDS for various AEDs delivery, which provides a promising approach to on-demand therapy of different epileptic seizures.

A stimuli-responsive nanocarrier for diagnosis of seizures and inhibition of glutaminase in epilepsy

Epilepsy is marked by unpredictable and recurrent episodes of seizures. It is characterized by glutamate excitotoxicity and changes in stimuli such as pH, temperature and oxidative environment. This study aimed to formulate novel nanoparticulate theranostic nanocarrier for combined effects of diagnosis and treatment of epilepsy by: i) in-situ detection of epileptic conditions through characteristic changes in pH through the synthesis of pH-responsive polymer (CS-g-PD) and ii) 'on-demand' therapeutic alleviation of epileptic seizures through an inhibitor of glutaminase, 6-diazo-5-oxo-norleucine (DON). The formulation of DON-CS-g-PD-SLNs possessed nanodimensions (∼197.56 ± 17.87) nm and zeta potential (4.19 ± 0.29), with entrapment efficiency of (80.29 ± 0.006%). The coating pH-responsive polymer showed good sensitivity for acidic conditions by releasing the drug in pH 6.4 and resisting release in higher pH 7.2. In-vivo studies in Wistar rats showed suppression of epileptic seizures, escalation in the duration latency and reduction in duration of convulsions and recovery period. Furthermore, it was also successful in reducing the levels of glutaminase (p<0.0001) in the brain of PTZ-kindled rats, thereby leading to a decrease in glutamate levels (p<0.01). Hence, the nanocarriers show promising potential as 'on-demand' theranostics in epilepsy by reducing both the incidence and severity of convulsions.

The blood-brain barrier: structure, regulation, and drug delivery

Blood-brain barrier (BBB) is a natural protective membrane that prevents central nervous system (CNS) from toxins and pathogens in blood. However, the presence of BBB complicates the pharmacotherapy for CNS disorders as the most chemical drugs and biopharmaceuticals have been impeded to enter the brain. Insufficient drug delivery into the brain leads to low therapeutic efficacy as well as aggravated side effects due to the accumulation in other organs and tissues. Recent breakthrough in materials science and nanotechnology provides a library of advanced materials with customized structure and property serving as a powerful toolkit for targeted drug delivery. In-depth research in the field of anatomical and pathological study on brain and BBB further facilitates the development of brain-targeted strategies for enhanced BBB crossing. In this review, the physiological structure and different cells contributing to this barrier are summarized. Various emerging strategies for permeability regulation and BBB crossing including passive transcytosis, intranasal administration, ligands conjugation, membrane coating, stimuli-triggered BBB disruption, and other strategies to overcome BBB obstacle are highlighted. Versatile drug delivery systems ranging from organic, inorganic, and biologics-derived materials with their synthesis procedures and unique physio-chemical properties are summarized and analyzed. This review aims to provide an up-to-date and comprehensive guideline for researchers in diverse fields, offering perspectives on further development of brain-targeted drug delivery system.

Insight into Drug Resistance in Status Epilepticus: Evidence from Animal Models

Status epilepticus (SE), a condition with abnormally prolonged seizures, is a severe type of epilepsy. At present, SE is not well controlled by clinical treatments. Antiepileptic drugs (AEDs) are the main therapeutic approaches, but they are effective for SE only with a narrow intervening window, and they easily induce resistance. Thus, in this review, we provide an updated summary for an insight into drug-resistant SE, hoping to add to the understanding of the mechanism of refractory SE and the development of active compounds. Firstly, we briefly outline the limitations of current drug treatments for SE by summarizing the extensive experimental literature and clinical data through a search of the PubMed database, and then summarize the common animal models of refractory SE with their advantages and disadvantages. Notably, we also briefly review some of the hypotheses about drug resistance in SE that are well accepted in the field, and furthermore, put forward future perspectives for follow-up research on SE.

Fighting Epilepsy with Nanomedicines-Is This the Right Weapon?

Epilepsy is a chronic and complex condition and is one of the most common neurological diseases, affecting about 50 million people worldwide. Pharmacological therapy has been, and is likely to remain, the main treatment approach for this disease. Although a large number of new antiseizure drugs (ASDs) has been introduced into the market in the last few years, many patients suffer from uncontrolled seizures, demanding the development of more effective therapies. Nanomedicines have emerged as a promising approach to deliver drugs to the brain, potentiating their therapeutic index. Moreover, nanomedicine has applied the knowledge of nanoscience, not only in disease treatment but also in prevention and diagnosis. In the current review, the general features and therapeutic management of epilepsy will be addressed, as well as the main barriers to overcome to obtain better antiseizure therapies. Furthermore, the role of nanomedicines as a valuable tool to selectively deliver drugs will be discussed, considering the ability of nanocarriers to deal with the less favourable physical-chemical properties of some ASDs, enhance their brain penetration, reduce the adverse effects, and circumvent the concerning drug resistance.

Activated astrocytes attenuate neocortical seizures in rodent models through driving Na+-K+-ATPase

Epileptic seizures are widely regarded to occur as a result of the excitation-inhibition imbalance from a neuro-centric view. Although astrocyte-neuron interactions are increasingly recognized in seizure, elementary questions about the causal role of astrocytes in seizure remain unanswered. Here we show that optogenetic activation of channelrhodopsin-2-expressing astrocytes effectively attenuates neocortical seizures in rodent models. This anti-seizure effect is independent from classical calcium signaling, and instead related to astrocytic Na+-K+-ATPase-mediated buffering K+, which activity-dependently inhibits firing in highly active pyramidal neurons during seizure. Compared with inhibition of pyramidal neurons, astrocyte stimulation exhibits anti-seizure effects with several advantages, including a wider therapeutic window, large-space efficacy, and minimal side effects. Finally, optogenetic-driven astrocytic Na+-K+-ATPase shows promising therapeutic effects in a chronic focal cortical dysplasia epilepsy model. Together, we uncover a promising anti-seizure strategy with optogenetic control of astrocytic Na+-K+-ATPase activity, providing alternative ideas and a potential target for the treatment of intractable epilepsy.

A Comprehensive Review of Cross-Linked Gels as Vehicles for Drug Delivery to Treat Central Nervous System Disorders

Gels are attractive candidates for drug delivery because they are easily producible while offering sustained and/or controlled drug release through various mechanisms by releasing the therapeutic agent at the site of action or absorption. Gels can be classified based on various characteristics including the nature of solvents used during preparation and the method of cross-linking. The development of novel gel systems for local or systemic drug delivery in a sustained, controlled, and targetable manner has been at the epitome of recent advances in drug delivery systems. Cross-linked gels can be modified by altering their polymer composition and content for pharmaceutical and biomedical applications. These modifications have resulted in the development of stimuli-responsive and functionalized dosage forms that offer many advantages for effective dosing of drugs for Central Nervous System (CNS) conditions. In this review, the literature concerning recent advances in cross-linked gels for drug delivery to the CNS are explored. Injectable and non-injectable formulations intended for the treatment of diseases of the CNS together with the impact of recent advances in cross-linked gels on studies involving CNS drug delivery are discussed.

Nanogels as Novel Nanocarrier Systems for Efficient Delivery of CNS Therapeutics

Nanogels have come out as a great potential drug delivery platform due to its prominently high colloidal stability, high drug loading, core-shell structure, good permeation property and can be responsive to environmental stimuli. Such nanoscopic drug carriers have more excellent abilities over conventional nanomaterials for permeating to brain parenchyma in vitro and in vivo. Nanogel-based system can be nanoengineered to bypass physiological barriers via non-invasive treatment, rendering it a most suitable platform for the management of neurological conditions such as neurodegenerative disorders, brain tumors, epilepsy and ischemic stroke, etc. Therapeutics of central nervous system (CNS) diseases have shown marked limited site-specific delivery of CNS by the poor access of various drugs into the brain, due to the presences of the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB). Hence, the availability of therapeutics delivery strategies is considered as one of the most major challenges facing the treatment of CNS diseases. The primary objective of this review is to elaborate the newer advances of nanogel for CNS drugs delivery, discuss the early preclinical success in the field of nanogel technology and highlight different insights on its potential neurotoxicity.

An H2R-dependent medial septum histaminergic circuit mediates feeding behavior

Novel targets for treating feeding-related diseases are of great importance, and histamine has long been considered an anorexigenic agent. However, understanding its functions in feeding in a circuit-specific way is still limited. Here, we report a medial septum (MS)-projecting histaminergic circuit mediating feeding behavior. This MS-projecting histaminergic circuit is functionally inhibited during food consumption, and bidirectionally modulates feeding behavior via downstream H2, but not H1, receptors on MS glutamatergic neurons. Further, we observed a pathological decrease of histamine 2 receptors (H2Rs) expression in MS glutamatergic neurons in diet-induced obesity (DIO) mice. Genetically, down-regulation of H2Rs expression in MS glutamatergic neurons accelerates body-weight gain. Importantly, chronic activation of H2Rs in MS glutamatergic neurons (with its clinical agonist amthamine) significantly slowed down the body-weight gain in DIO mice, providing a possible clinical utility to treat obesity. Together, our results demonstrate that this MS-projecting histaminergic circuit is critically involved in feeding, and H2Rs in MS glutamatergic neurons is a promising target for treating body-weight problems.

The GluN2B-Trp373 NMDA Receptor Variant is Associated with Autism-, Epilepsy-Related Phenotypes and Reduces NMDA Receptor Currents in Rats

Autism spectrum disorder (ASD) is a neurodevelopmental condition with core clinical features of abnormal communication, social interactions, atypical intelligence, and a higher risk of epilepsy. Prior work has suggested that de novo heterozygous mutations in the GRIN2B gene that encodes the GluN2B subunit of N-methyl-D-aspartic acid receptors are likely linked to ASD. However, whether GLuN2B-Trp373 mutation derived from autistic individuals causes ASD-like behavioral aberrations in rats remains to be determined. Here, through in utero electroporation and in vivo studies, we conducted a battery of tests to examine ASD-associated behaviors, cognitive impairments, and susceptibility to pentylenetetrazol-induced seizures. Whole-cell patch recording was utilized to determine whether the GluN2B-Trp373 mutation influences GluN2B-containing NMDA receptor currents in rats. Results show that, behaviorally, GLuN2B-Trp373 mutant rats exhibited core behavioral manifestations of ASD, such as social interaction deficits, increases in stereotyped behaviors and anxiety stereotyped/repetitive, impaired spatial memory, and enhanced risk of pentylenetetrazol-induced seizures, consistent with many of the hallmarks of low-functioning ASD in humans. Functionally, the GluN2B-Trp373 mutation results in reduced GluN2B surface protein expression together with decreased hippocampal NMDA receptor currents. Collectively, our findings highlight that GluN2B-Trp373 mutations can drive the manifestation of ASD-associated symptoms via the suppression of NMDA receptor currents.

Nanoengineered on-demand drug delivery system improves efficacy of pharmacotherapy for epilepsy

Long-term pharmacotherapy, serving as the main therapeutic approach for epilepsy prophylaxis, has suffered from limited efficacy and potential side effects because of the blood-brain barrier (BBB) and untimely medication. Here, we reported a nanoengineered drug delivery system for synergistic brain-targeting delivery and on-demand drug release of antiepileptic drugs (AEDs). The dopamine-pyrrole hybrid system can improve delivery efficiency through a combination of receptor-mediated transcytosis and BBB disruption–enabled transport induced by photothermal conversion of near-infrared light. Incorporation of polydopamine endowed the delivery system with enhanced conductivity and sensitivity, giving sustained (2 hours) and rapid (30 s) drug release in response to epileptiform discharges. Acute, continuous, and spontaneous seizure models validated that the delivery system could inhibit seizures upon epileptiform abnormalities, treated by one-fifth of the conventional dosage. Complemented with satisfactory biosafety results, this “smart” modality is promising to be an effective and safe strategy to improve the therapeutic index of AEDs for epilepsy.

Electroresponsive Hydrogels for Therapeutic Applications in the Brain

Electroresponsive hydrogels possess a conducting material component and respond to electric stimulation through reversible absorption and expulsion of water. The high level of hydration, soft elastomeric compliance, biocompatibility, and enhanced electrochemical properties render these hydrogels suitable for implantation in the brain to enhance the transmission of neural electric signals and ion transport. This review provides an overview of critical electroresponsive hydrogel properties for augmenting electric stimulation in the brain. A background on electric stimulation in the brain through electroresponsive hydrogels is provided. Common conducting materials and general techniques to integrate them into hydrogels are briefly discussed. This review focuses on and summarizes advances in electric stimulation of electroconductive hydrogels for therapeutic applications in the brain, such as for controlling delivery of drugs, directing neural stem cell differentiation and neurogenesis, improving neural biosensor capabilities, and enhancing neural electrode-tissue interfaces. The key challenges in each of these applications are discussed and recommendations for future research are also provided.

Intranasal delivery of phenytoin-loaded nanoparticles to the brain suppresses pentylenetetrazol-induced generalized tonic clonic seizures in an epilepsy mouse model

In this work we describe the preparation and characterization of lecithin-chitosan nanoparticles (L₁₀C_i⁺), and investigate their ability to deliver the anti-epileptic drug phenytoin (PHT) to mouse brain following intranasal (IN) administration. L₁₀C_i⁺ were retained in the nasal cavity compared to PHT in PEG200 solution (PHT/PEG), which suffered immediate nasal drainage. PHT was detected in the brain after 5 min of IN administration reaching a maximum of 11.84 ± 2.31 %ID g^-1 after 48 hours. L₁₀C_i⁺ were associated with a higher brain/plasma ratio (C_b/p) compared to the experimental control comprising free PHT injected via the intraperitoneal route (PHT-IP) across all tested time points. Additionally, L₁₀C_i⁺ led to lower PHT accumulation in the liver and spleen compared to PHT-IP, which is vital for lowering the systemic side effects of PHT. The relatively high drug targeting efficiency (DTE%) of 315.46% and the drug targeting percentage (DTP%) of 68.29%, combined with the increasing anterior-to-posterior gradient of PHT in the brain confirmed the direct nose-to-brain transport of PHT from L₁₀C_i⁺. Electroencephalogram (EEG) analysis was used to monitor seizure progression. L₁₀C_i⁺ resulted in a complete seizure suppression after 4 hours of administration, and this inhibition persisted even with an 8-fold reduction of the encapsulated dose compared to the required PHT-IP dose to achieve a similar inhibitory effect due to systemic loss. The presented findings confirm the possibility of using L₁₀C_i⁺ as a non-invasive delivery system of PHT for the management of epilepsy using reduced doses of PHT.

New advances in pharmacoresistant epilepsy towards precise management-from prognosis to treatments

Epilepsy, one of the most severe neurological diseases, is characterized by abrupt recurrent seizures. Despite great progress in the development of antiseizure drugs (ASDs) based on diverse molecular targets, more than one third of epilepsy patients still show resistance to ASDs, a condition termed pharmacoresistant epilepsy. The management of pharmacoresistant epilepsy involves serious challenges. In the past decade, promising advances have been made in the use of interdisciplinary techniques involving biophysics, bioinformatics, biomaterials and biochemistry, which allow more precise prognosis and development of drug target for pharmacoresistant epilepsy. Notably, novel experimental tools such as viral vector gene delivery, optogenetics and chemogenetics have provided a framework for promising approaches to the precise treatment of pharmacoresistant epilepsy. In this review, historical achievements especially recent advances of the past decade in the prognosis and treatment of pharmacoresistant epilepsy from both clinical and laboratory settings are presented and summarized. We propose that the further development of novel experimental tools at cellular or molecular levels with both temporal and spatial precision are necessary to make improve the management and drug development for pharmacoresistant epilepsy in the clinical arena.

Long-term music adjuvant therapy enhances the efficacy of sub-dose antiepileptic drugs in temporal lobe epilepsy

Aims

Noninvasive music adjuvant therapy shows great potential in improving seizure control when combined with routine antiepileptic drugs. However, the diversity of previous music protocols has resulted in disparate outcomes. The optimized protocol and features for music adjuvant therapy are still not fully understood which limits its feasibility.

Methods

By applying different regimens of music therapy in various temporal lobe epilepsy models, we evaluated the effect of music in combination with sub‐dose drugs on epileptic seizures to determine the optimized protocol.

Results

A subgroup of kindled mice that were responsive to music adjuvant therapy was screened. In those mice, sub‐dose drugs which were noneffective on kindled seizures, alleviated seizure severity after 12 h/day Mozart K.448 for 14 days. Shorter durations of music therapy (2 and 6 h/day) were ineffective. Furthermore, only full‐length Mozart K.448, not its episodes or other music varieties, was capable of enhancing the efficacy of sub‐dose drugs. This music therapeutic effect was not due to increasing cerebral drug concentration, but instead was related with the modulation of seizure electroencephalogram (EEG) spectral powers in the hippocampus.

Conclusion

These results indicate that long‐term full‐length Mozart K.448 could enhance the anti‐seizure efficacy of sub‐dose drugs and may be a promising noninvasive adjuvant therapy for temporal lobe epilepsy.

Recent advances on drug delivery nanocarriers for cerebral disorders

Pharmacotherapies for brain disorders are generally faced with obstacles from the blood-brain barrier (BBB). There are a variety of drug delivery systems that have been put forward to cross or bypass the BBB with the access to the central nervous system. Brain drug delivery systems have benefited greatly from the development of nanocarriers, including lipids, polymers and inorganic materials. Consequently, various kinds of brain drug delivery nano-systems have been established, such as liposomes, polymeric nanoparticles (PNPs), nanomicelles, nanohydrogels, dendrimers, mesoporous silica nanoparticles and magnetic iron oxide nanoparticles. The characteristics of their carriers and preparations usually differ from each other, as well as their transportation mechanisms into intracerebral lesions. In this review, different types of brain drug delivery nanocarriers are classified and summarized, especially their significant achievements, to present several recommendations and directions for future strategies of cerebral delivery.

Polymeric nanoencapsulation of zaleplon into PLGA nanoparticles for enhanced pharmacokinetics and pharmacological activity

Zaleplon (ZP) is a sedative and hypnotic drug used for the treatment of insomnia. Despite its potent anticonvulsant activity, ZP is not commonly used for the treatment of convulsion since ZP is characterized by its low oral bioavailability as a result of poor solubility and extensive liver metabolism. The following study aimed to formulate specifically controlled release nano-vehicles for oral and parenteral delivery of ZP to enhance its oral bioavailability and biological activity. A modified single emulsification-solvent evaporation method of sonication force was adopted to optimize the inclusion of ZP into biodegradable nanoparticles (NPs) using poly (dl-lactic-co-glycolic acid) (PLGA). The impacts of various formulation variables on the physicochemical characteristics of the ZP-PLGA-NPs and drug release profiles were investigated. Pharmacokinetics and pharmacological activity of ZP-PLGA-NPs were studied using experimental animals and were compared with generic ZP tablets. Assessment of gamma-aminobutyric acid (GABA) level in plasma after oral administration was conducted using enzyme-linked immunosorbent assay. The maximal electroshock-induced seizures model evaluated anticonvulsant activity after the parenteral administration of ZP-loaded NPs. The prepared ZP-PLGA NPs were negatively charged spherical particles with an average size of 120-300 nm. Optimized ZP-PLGA NPs showed higher plasma GABA levels, longer sedative, hypnotic effects, and a 3.42-fold augmentation in oral drug bioavailability in comparison to ZP-marketed products. Moreover, parenteral administration of ZP-NPs showed higher anticonvulsant activity compared to free drug. Oral administration of ZP-PLGA NPs achieved a significant improvement in the drug bioavailability, and parenteral administration showed a pronounced anticonvulsant activity.

Exploration of Inbuilt Novel Properties as Bioretardant Cum Stabilizer of Isolated Biopolymer from Fragaria ananassa in Delivery of Nanosized Phenytoin

The research aims to develop bionanosuspension using a biopolymer isolated from Fragaria ananassa fruit that constitutes potential and natural polymeric properties. At first, the biomaterial was isolated from the natural fruit pulp of Fragaria ananassa by an economical method of isolation. The model drug was nanosized by a novel sonication method. The isolated biopolymer was characterized for its polymeric properties, and its potential capabilities were evaluated in the delivery of nanosized phenytoin. The isolated biopolymer was characterized for DSC, FTIR, NMR, mass, and scanning electron microscopy. The isolated biomaterial was used for the preparation of phenytoin-loaded bionanosuspension with other excipients. The bionanoparticles were also characterized by different analytical testing such as FTIR, DSC, and SEM to confirm any interaction between model drug and biopolymer. The prepared bionanoparticles showed the release of phenytoin in a sustained manner over 36 hours. The release kinetic study was done using the BIT-SOFT 1.12 software and other parameters such as t50%, t80%, and r ² were calculated. The formulation PFr6 was considered best having t50% in 18.22 hours and t80% in 29.62 h with an r² value of 0.9793. This formulation showed up to 87.89% drug release within 36 hours. The prepared bio-nanosuspension was found to be stable and in a well-dispersed state. The dried bionanosuspension evaluation revealed no interaction between model drug and biopolymer without any loss of characteristic peaks. Therefore, the isolated biopolymer can be safely used to prepare stable bionanosuspension loaded with nanosized phenytoin.

Management of epileptic disorders using nanotechnology-based strategies for nose-to-brain drug delivery

INTRODUCTION

Epilepsy, a major neurological disorder affects about 1% of the Indian population. The discovery of noninvasive strategies for epilepsy presents a challenge for the scientists. Different types of nose-to-brain dosage-forms have been studied for epilepsy management. It aims to give new perspectives for developing new and existing anti-epileptic drugs. Combining nanotechnology with nose-to-brain approach can help in promoting the treatment efficacy by site-specific delivery. Also, it will minimize the side-effects and patient noncompliance observed in conventional administration routes. Peptide delivery can be an interesting approach for the management of epilepsy. Drug-loaded intranasal nanoformulations exhibit diverse prospective potentials in the management of epilepsy. Considering that, nanotherapy using nose-to-brain delivery as a prospective technique for the efficient management of epilepsy is reviewed.

AREAS COVERED

The authors have compiled all recently available data pertaining to the nose-to-brain delivery of therapeutics using nanotechnological strategies. The fundamental mechanism of nose-to-brain delivery, claims for intranasal delivery and medical devices for epilepsy are discussed.

EXPERT OPINION

Drug-loaded intranasal nanoformulations exhibit different prospective potentials in the management of epilepsy. Considering the foregoing research done in the field of nanotechnology, globally, authors propose nose-to-brain delivery of nanoformulations as a potential technique for the efficient management of epilepsy.

Nanotechnology as a Platform for the Development of Injectable Parenteral Formulations: A Comprehensive Review of the Know-Hows and State of the Art

Within recent decades, the development of nanotechnology has made a significant contribution to the progress of various fields of study, including the domains of medical and pharmaceutical sciences. A substantially transformed arena within the context of the latter is the development and production of various injectable parenteral formulations. Indeed, recent decades have witnessed a rapid growth of the marketed and pipeline nanotechnology-based injectable products, which is a testimony to the remarkability of the aforementioned contribution. Adjunct to the ability of nanomaterials to deliver the incorporated payloads to many different targets of interest, nanotechnology has substantially assisted to the development of many further facets of the art. Such contributions include the enhancement of the drug solubility, development of long-acting locally and systemically injectable formulations, tuning the onset of the drug’s release through the endowment of sensitivity to various internal or external stimuli, as well as adjuvancy and immune activation, which is a desirable component for injectable vaccines and immunotherapeutic formulations. The current work seeks to provide a comprehensive review of all the abovementioned contributions, along with the most recent advances made within each domain. Furthermore, recent developments within the domains of passive and active targeting will be briefly debated.

Phenytoin-loaded lipid-core nanocapsules improve the technological properties and in vivo performance of fluidised bed granules

Lipid-core nanocapsules (LNCs) were recently reported by our group as a suitable binder system to produce fluidised bed granules. However, there is still a lack of knowledge about the influence of using these nanocarriers loaded with a drug on the properties of the granules and their in vivo performance. Therefore, this study was designed to produce innovative fluidised bed granules containing phenytoin-loaded LNCs (LNC_PHT) as a strategy to evaluate the influence of the presence of the drug-loaded nanocarriers on their in vitro and in vivo properties. Granules were produced using a mixture of maltodextrin and phenytoin (1:0.004 w/w) as substrate. They were prepared by fluid bed granulation using water or LNC_PHT as the liquid binder, affording good yields (73-82%) of granules with low moisture content (<5%). Granules prepared with LNC_PHT had larger mean size (122 μm) compared to maltodextrin primary particles (50 μm) due to the formation of solid bridges. Moreover, the use of LNC_PHT as the liquid binder improved their powder flow properties. The nanocarriers were recovered after aqueous dispersion (3.00 mg.mL^-1 of PHT) with a redispersibility close to 90%. After reconstitution in water, granules containing LNC_PHT showed an improved dissolution behaviour compared to those prepared without them. In addition, they showed a higher mucoadhesive effect due to a combined effect of the LNC_PHT and maltodextrin in the interactions with porcine intestinal mucosa. Regarding the in vivo studies, granules containing the combination of non-encapsulated PHT and PHT-loaded lipid-core nanocapsules increased the latency to seizures compared to placebo granules, showing effective anticonvulsant effect in mice. In conclusion, the use of drug-loaded nanocapsules as binder is an encouraging approach to produce fluidised bed mucoadhesive granules with improved technological properties and in vivo performance.

Nanocage encapsulation improves antiepileptic efficiency of phenytoin

More than 30% of patients with epilepsy progress to drug-resistant epilepsy, leading to a significant increase in morbidity and mortality of epilepsy. The limitation of epileptic drug to reach the epileptogenic focus is the critical reason, and the blood-brain barrier (BBB) plays a crucial role. Here, we successfully constructed a hepatitis B core (HBc) protein nanocage (NC) with the insertion of brain target TGN peptide for facilitating epileptic drug phenytoin delivery to the brain. Our results demonstrated that this nanocage can specifically and efficiently target the brain tissue by 2.4 fold and increase the antiepileptic efficiency of phenytoin about 100 fold in pilocarpine induced models of epilepsy. Both in vivo mice and in vitro human neural three-dimensional cortical organoids demonstrated high penetration ability. These functions are achieved through the facilitation of brain target peptide TGN rather than disruption of brain blood barrier. In summary, we presented an efficient antiepileptic drug delivery nanocage for the treatment of refractory epilepsy. Moreover, this therapeutic modulation also provides promising strategy for other intractable neurological disease.

Tetramethylpyrazine Reduces Epileptogenesis Progression in Electrical Kindling Models by Modulating Hippocampal Excitatory Neurotransmission

Antiepileptic drugs (AEDs) are the primary agents prescribed for clinical management of limbic epilepsy. However, high incidence of pharmacoresistance and a limited armory of drugs for inhibiting the pathological progression of epilepsy pose major obstacles to managing epilepsy. Here, we investigated the effect of tetramethylpyrazine (TMP), the main bioactive alkaloid isolated from the oriental medicine Ligusticum chuanxiong Hort., against the epileptogenesis progression of acute hippocampal and corneal (6 Hz) electrical kindling models of TLE. TMP dose-dependently limited the progression of seizures and reduced the after-discharge duration (ADDs) in a hippocampal mouse kindling model. Mice treated with TMP (20, 50 mg/kg, i.p.) remained in stage 1 of epileptic progression for a protracted period, requiring additional stimulation to induce stages 2-5 epileptic phenotypes. TMP (50 mg/kg) also inhibited 6 Hz corneal kindling progression. In contrast, TMP did not reverse the phenotypes induced in a generalized seizures (GS) model, or the maximal electroshock (MES) or pentylenetetrazole (PTZ)-induced models of epilepsy. Furthermore, patch clamp recordings revealed no effect of TMP (10 μM) on CA1 hippocampal neurons' intrinsic properties but suppressed the (i) frequency of spontaneous excitatory post synaptic currents (sEPSCs), (ii) paired pulse ratio (PPR), and (iii) long-term potentiation (LTP) induction in the Schaffer collateral-CA1 pathway. TMP suppressed the activity of calcium, but not sodium, channels. Taken together, these results suggest that TMP has an antiepileptogenic effect, likely through suppression of excitatory synaptic transmission by its effects on inhibition of calcium channels; these traits distinguish TMP from currently available AEDs. As mice administered TMP did not show any neurologic impairment in the object recognition and open field tests, the data support further development of TMP as a promising treatment for epilepsy.

Approaches for encephalic drug delivery using nanomaterials: The current status

Nanotechnology, the investigation of little structures, ranging from the size of 1 nm-100 nm presents a breakthrough in the field of targeted drug delivery. The microvasculature in the human brain along with the blood brain barrier (BBB) offers high resistance to the entry of therapeutics agents and other substances in to the brain. Nanoparticles have certain advantages as high permeability, reactivity, surface area and quantum properties and it also meets various medical challenges which may include poor bioavailability, difficulty in targeting, organ toxicity etc. The use of nanoparticles in pharmaceuticals has been inspired by various natural nanomaterials found in the body, which includes proteins, lipids etc. A brief explanation of different types of pharmaceutical approaches used in brain drug delivery is discussed here. Nanotechnology is used treatment of many illnesses which also include diseases related to the brain such as gliomas, epilepsy, migraine, cerebrovascular disease, Parkinson's disease etc., Different type of nanoparticles are prepared, such as polymer-based nanoparticles, metallic nanoparticles, carbon-based nanoparticles, lipid-based nanoparticles, ceramic nanoparticles semiconductor nanoparticles and are studied for their usefulness in drug delivery. The primary function of nanoparticles is to deliver drug moiety to the desired targeted site by overcoming permeability issues. The shape, size and surface area nanoparticles help in increasing the bioavailability, drug retention and multiple drug delivery. Mechanisms of nanoparticles crossing BBB can be divided into passive and active transport, are briefly explained.

A Role for Nanoparticles in Treating Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the main causes of disability in children and young adults, as well as a significant concern for elderly individuals. Depending on the severity, TBI can have a long-term impact on the quality of life for survivors of all ages. The primary brain injury can result in severe disability or fatality, and secondary brain damage can increase the complexities in cellular, inflammatory, neurochemical, and metabolic changes in the brain, which can last decades post-injury. Thus, survival from a TBI is often accompanied by lifelong disabilities. Despite the significant morbidity, mortality, and economic loss, there are still no effective treatment options demonstrating an improved outcome in a large multi-center Phase III trial, which can be partially attributed to poor target engagement of delivered therapeutics. Thus, there is a significant unmet need to develop more effective delivery strategies to overcome the biological barriers that would otherwise inhibit transport of materials into the brain to prevent the secondary long-term damage associated with TBI. The complex pathology of TBI involving the blood-brain barrier (BBB) has limited the development of effective therapeutics and diagnostics. Therefore, it is of great importance to develop novel strategies to target the BBB. The leaky BBB caused by a TBI may provide opportunities for therapeutic delivery via nanoparticles (NP). The focus of this review is to provide a survey of NP-based strategies employed in preclinical models of TBI and to provide insights for improved NP based diagnostic or treatment approaches. Both passive and active delivery of various NPs for TBI are discussed. Finally, potential therapeutic targets where improved NP-mediated delivery could increase target engagement are identified with the overall goal of providing insight into open opportunities for NP researchers to begin research in TBI.

A window into the brain: Tools to assess pre-clinical efficacy of biomaterials-based therapies on central nervous system disorders

Therapeutic conveyance into the brain is a cardinal requirement for treatment of diverse central nervous system (CNS) disorders and associated pathophysiology. Effectual shielding of the brain by the blood-brain barrier (BBB) sieves out major proportion of therapeutics with the exception of small lipophilic molecules. Various nano-delivery systems (NDS) provide an effective solution around this obstacle owing to their small size and targeting properties. To date, these systems have been used for several pre-clinical disease models including glioma, neurodegenerative diseases and psychotic disorders. An efficacy screen for these systems involves a test battery designed to probe into the multiple facets of therapeutic delivery. Despite their wide application in redressing various disease targets, the efficacy evaluation strategies for all can be broadly grouped into four modalities, namely: histological, bio-imaging, molecular and behavioural. This review presents a comprehensive insight into all of these modalities along with their strengths and weaknesses as well as perspectives on an ideal design for a panel of tests to screen brain nano-delivery systems.

An update for epilepsy research and antiepileptic drug development: Toward precise circuit therapy

Epilepsy involves neuronal dysfunction at molecular, cellular, and circuit levels. The understanding of the mechanism of the epilepsies has advanced greatly in the last three decades, especially in terms of their cellular and molecular basis. However, despite the availability of ~30 anti-epileptic drugs (AEDs) with diverse molecular targets, there are still many challenges (e.g. drug resistance, side effects) in pharmacological treatment of epilepsies today. Because molecular mechanisms are integrated at the level of neuronal circuits, we suggest a shift in epilepsy treatment and research strategies from the "molecular" level to the "circuit" level. Recent technological advances have facilitated circuit mechanistic discovery at each level and have paved the way for many opportunities of novel therapeutic strategies and AED development toward precise circuit therapy.

Pharmaco-genetic therapeutics targeting parvalbumin neurons attenuate temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is the most common type of epilepsy and is often medically refractory. Previous studies suggest that selective pharmaco-genetic inhibition of pyramidal neurons has therapeutic value for the treatment of epilepsy, however there is a risk of disrupting normal physical functions. Here, we test whether pharmaco-genetic activation of parvalbumin neurons, which are transgenetically transduced with the modified muscarinic receptor hM3Dq can attenuate TLE. We found that pharmaco-genetic activation of hippocampal parvalbumin neurons in epileptogenic zone not only significantly extends the latency to different seizure stages and attenuates seizure activities in acute seizure model, but also greatly alleviates the severity of seizure onsets in two chronic epilepsy models. This manipulation did not affect the normal physical function evaluated in various cognitive tasks. Further, the activation of parvalbumin neurons produced an inhibition on parts of surrounding pyramidal neurons, and the direct inactivation of pyramidal neurons via the viral expression of a modified muscarinic receptor hM4Di produced a similar anti-ictogenic effect. Interestingly, pharmaco-genetic inactivation of pyramidal neurons was more sensitive to impair cognitive function. Those data demonstrated that pharmaco-genetic seizure attenuation through targeting parvalbumin neurons rather than pyramidal neurons may be a novel and relatively safe approach for treating refractory TLE.

Design strategies for physical-stimuli-responsive programmable nanotherapeutics

Nanomaterials that respond to externally applied physical stimuli such as temperature, light, ultrasound, magnetic field and electric field have shown great potential for controlled and targeted delivery of therapeutic agents. However, the body of literature on programming these stimuli-responsive nanomaterials to attain the desired level of pharmacologic responses is still fragmented and has not been systematically reviewed. The purpose of this review is to summarize and synthesize the literature on various design strategies for simple and sophisticated programmable physical-stimuli-responsive nanotherapeutics.

Phenytoin: 80 years young, from epilepsy to breast cancer, a remarkable molecule with multiple modes of action

In 1908 phenytoin (5,5-diphenylhydantoin) was first synthesized as a barbiturate derivative in Germany by professor Heinrich Biltz (1865-1943) and subsequently resynthesized by an American chemist of the pharmaceutical company Parke-Davis in 1923 in Detroit. Screening phenytoin did not reveal comparable sedative side effects as barbiturates and, thus, Parke-Davis discarded this compound as a useful drug. In 1936, phenytoin's anticonvulsive properties were identified via a new animal model for convulsive disorders, developed by Putnam and Merritt, who also evaluated its clinical value in a number of patients in the period 1937-1940. For many diseases, mechanism of action of phenytoin remains obscure. The voltage-gated sodium channel was and is generally regarded as the main target to explain phenytoin's activity as an anticonvulsant and an anti-arrhythmic drug. This target, however, does not explain many of the other clinical properties of phenytoin. We will explore a number of original articles on phenytoin published in its 80 years history and give extra attention to the various hypothesis and experiments done to elucidate its mechanisms of action. Phenytoin has been explored in over 100 different disorders; the last two promising indications tested in the clinic are breast cancer and optic neuritis. Most probably, there are multiple targets active for these various disorders, and the insight into which targets are relevant is still very incomplete. It is remarkable that many pharmacological studies tested one dose only, mostly 50 or 100 μM, doses which most probably are higher than the non-plasma bound phenytoin plasma levels obtained during treatment.

Systems-level thinking for nanoparticle-mediated therapeutic delivery to neurological diseases

Neurological diseases account for 13% of the global burden of disease. As a result, treating these diseases costs $750 billion a year. Nanotechnology, which consists of small (~1-100 nm) but highly tailorable platforms, can provide significant opportunities for improving therapeutic delivery to the brain. Nanoparticles can increase drug solubility, overcome the blood-brain and brain penetration barriers, and provide timed release of a drug at a site of interest. Many researchers have successfully used nanotechnology to overcome individual barriers to therapeutic delivery to the brain, yet no platform has translated into a standard of care for any neurological disease. The challenge in translating nanotechnology platforms into clinical use for patients with neurological disease necessitates a new approach to: (1) collect information from the fields associated with understanding and treating brain diseases and (2) apply that information using scalable technologies in a clinically-relevant way. This approach requires systems-level thinking to integrate an understanding of biological barriers to therapeutic intervention in the brain with the engineering of nanoparticle material properties to overcome those barriers. To demonstrate how a systems perspective can tackle the challenge of treating neurological diseases using nanotechnology, this review will first present physiological barriers to drug delivery in the brain and common neurological disease hallmarks that influence these barriers. We will then analyze the design of nanotechnology platforms in preclinical in vivo efficacy studies for treatment of neurological disease, and map concepts for the interaction of nanoparticle physicochemical properties and pathophysiological hallmarks in the brain. WIREs Nanomed Nanobiotechnol 2017, 9:e1422. doi: 10.1002/wnan.1422 For further resources related to this article, please visit the WIREs website.