Vitamin-Derived Nanolipoidal Carriers for Brain Delivery of Dimethyl Fumarate: A Novel Approach with Preclinical Evidence

Promises of Lipid-Based Nanocarriers for Delivery of Dimethyl Fumarate to Multiple Sclerosis Brain

Multiple sclerosis (MS) is a neurodegenerative autoimmune disorder of the central nervous system (CNS) infecting 2.5 million people worldwide. It is the most common nontraumatic neurological impairment in young adults. The blood-brain barrier rupture for multiple sclerosis pathogenesis has two effects: first, during the onset of the immunological attack, and second, for the CNS self-sustained "inside-out" demyelination and neurodegeneration processes. In addition to genetic variations, environmental and lifestyle variables can also significantly increase the risk of developing MS. Dimethyl fumarate (DMF) and sphingosine-1-phosphate (S1P) receptor modulators that may pass the blood-brain barrier and have positive direct effects in the CNS with quite diverse mechanisms of action raise the possibility that a combination therapy could be successful in treating MS. Lipid nanocarriers are recognized as one of the best drug delivery techniques to the brain for effective brain delivery. Numerous scientific studies have shown that lipid nanoparticles can enhance the lipid solubility, oral bioavailability, and brain availability of the drugs. Nanolipidic carriers for DMF delivery could be derived through vitamin D, tocopherol acetate, stearic acid, quercetin, cell-mimicking platelet-based, and chitosan-alginate core-shell-corona-shaped nanoparticles. Clinical and laboratory diagnosis of MS can be performed mainly through magnetic resonance imaging. The advancements in nanotechnology have enabled the clinicians to cross the blood-brain barrier and to target the brain and central nervous system of the patient with multiple sclerosis.

The Challenge of Dimethyl Fumarate Repurposing in Eye Pathologies

Dimethyl fumarate (DMF) is a small molecule currently approved and used in the treatment of psoriasis and multiple sclerosis due to its immuno-modulatory, anti-inflammatory, and antioxidant properties. As an Nrf2 activator through Keap1 protein inhibition, DMF unveils a potential therapeutical use that is much broader than expected so far. In this comprehensive review we discuss the state-of-art and future perspectives regarding the potential repositioning of this molecule in the panorama of eye pathologies, including Age-related Macular Degeneration (AMD). The DMF's mechanism of action, an extensive analysis of the in vitro and in vivo evidence of its beneficial effects, together with a search of the current clinical trials, are here reported. Altogether, this evidence gives an overview of the new potential applications of this molecule in the context of ophthalmological diseases characterized by inflammation and oxidative stress, with a special focus on AMD, for which our gene-disease (KEAP1-AMD) database search, followed by a protein-protein interaction analysis, further supports the rationale of DMF use. The necessity to find a topical route of DMF administration to the eye is also discussed. In conclusion, the challenge of DMF repurposing in eye pathologies is feasible and worth scientific attention and well-focused research efforts.

Recent advancements in nanoparticle-mediated approaches for restoration of multiple sclerosis

Multiple Sclerosis (MS) is an autoimmune disease with complicated immunopathology which necessitates considering multifactorial aspects for its management. Nano-sized pharmaceutical carriers named nanoparticles (NPs) can support impressive management of disease not only in early detection and prognosis level but also in a therapeutic manner. The most prominent initiator of MS is the domination of cellular immunity to humoral immunity and increment of inflammatory cytokines. The administration of several platforms of NPs for MS management holds great promise so far. The efforts for MS management through in vitro and in vivo (experimental animal models) evaluations, pave a new way to a highly efficient therapeutic means and aiding its translation to the clinic in the near future.

Nanoparticles in Combating Neuronal Dysregulated Signaling Pathways: Recent Approaches to the Nanoformulations of Phytochemicals and Synthetic Drugs Against Neurodegenerative Diseases

As the worldwide average life expectancy has grown, the prevalence of age-related neurodegenerative diseases (NDDs) has risen dramatically. A progressive loss of neuronal function characterizes NDDs, usually followed by neuronal death. Inflammation, apoptosis, oxidative stress, and protein misfolding are critical dysregulated signaling pathways that mainly orchestrate neuronal damage from a mechanistic point. Furthermore, in afflicted families with genetic anomalies, mutations and multiplications of α-synuclein and amyloid-related genes produce some kinds of NDDs. Overproduction of such proteins, and their excessive aggregation, have been proven in various models of neuronal malfunction and death. In this line, providing multi-target therapies carried by novel delivery systems would pave the road to control NDDs through simultaneous modulation of such dysregulated pathways. Phytochemicals are multi-target therapeutic agents, which employ several mechanisms towards neuroprotection. Besides, the blood-brain barrier (BBB) is a critical issue in managing NDDs since it inhibits the accessibility of drugs to the brain in sufficient concentration. Besides, discovering novel delivery systems is vital to improving the efficacy, bioavailability, and pharmacokinetic of therapeutic agents. Such novel formulations are also employed to improve the drug's biodistribution, allow for the co-delivery of several medicines, and offer targeted intracellular delivery against NDDs. The present review proposes nanoformulations of phytochemicals and synthetic agents to combat NDDs by modulating neuroinflammation, neuroapoptosis, neuronal oxidative stress pathways and protein misfolding.

Engineered Solid Lipid Nanoparticles and Nanostructured Lipid Carriers as New Generations of Blood-Brain Barrier Transmitters

The blood-brain barrier (BBB) is considered as the most challenging barrier in brain drug delivery. Indeed, there is a definite link between the BBB integrity defects and central nervous systems (CNS) disorders, such as neurodegenerative diseases and brain cancers, increasing concerns in the contemporary era because of the inability of most therapeutic approaches. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) have already been identified as having several advantages in facilitating the transportation of hydrophilic and hydrophobic agents across the BBB. This review first explains BBB functions and its challenges in brain drug delivery, followed by a brief description of nanoparticle-based drug delivery for brain diseases. A detailed presentation of recent progressions in optimizing SLNs and NLCs for controlled release drug delivery, gene therapy, targeted drug delivery, and diagnosis of neurodegenerative diseases and brain cancers is approached. Finally, the problems, challenges, and future perspectives in optimizing these carriers for potential clinical application were described briefly.

QbD-steered development of mixed nanomicelles of galantamine: Demonstration of enhanced brain uptake, prolonged systemic retention and improved biopharmaceutical attributes

PURPOSE

Numerous oral treatment options have been reported for neurological disorders, especially Alzheimer's disease (AD). Galantamine (GAL) is one of such drugs duly approved for management of AD. However, it exhibits poor brain penetration, low intestinal permeation and requires frequent dosing in AD treatment. The present studies, accordingly, were undertaken to develop DSPE-PEG 2000-based micelles loaded with GAL for efficient brain uptake, improved and extended pharmacokinetics, along with reduced dosing regimen.

METHODS

Mixed nanomicelles (MNMs) were systematically formulated using QbD approach, and characterized for morphology, entrapment efficiency andin vitrodrug release.

RESULTS

Studies on CaCo-2 and neuronal U-87 cell lines exhibited substantial enhancement in the cellular permeability and uptake of the developed MNMs. Pharmacokinetic studies performed on rats showed significantly improved values of plasma AUC (i.e., 2.28-fold, p < 0.001), ostensibly due to bypassing of hepatic first-pass metabolism and improved intestinal permeability, together with significant rise in MRT (2.08-fold, p < 0.001) and t_max (4.80-fold; p < 0.001) values, indicating immense potential for prolonged drug residence in body.Besides, substantial elevation in brain drug levels, distinctly improved levels of biochemical parameters in brain homogenates and cognitive improvement in β-amyloid-treated rats, testify the superiority in MNMs in therapeutic management of AD.

CONCLUSIONS

The preclinical findings of the developed nanocarrier systems successfully demonstrate the notable potential of enhanced drug efficacy, extended duration of action and improved patient compliance.

Curcumin Loaded and Co-loaded Nanosystems: A Review from a Biological Activity Enhancement Perspective

BACKGROUND

Curcumin is a natural phenolic compound exhibiting multiple bioactivities that have been evaluated in vitro, in vivo as well as through clinical studies in humans. Some of them include antimicrobial, antioxidant, anti-inflammatory, and central nervous system protective effects. Further, curcumin is generally recognized as a safe substance because of its low toxicity. However, its molecular structure is susceptible to changes in pH, oxidation, photodegradation, low aqueous solubility, and biotransformation compromising its bioavailability; these drawbacks are successfully addressed through nanotechnology.

OBJECTIVE

The present review systematizes findings on the enhancement of curcumin's beneficial effects when it is loaded and co-loaded into different types of nanosystems covering liposomes, polymeric and solid-lipid nanoparticles, nanostructured lipid carrier, lipid-polymeric hybrids, self- -assembled and protein-based core-shell systems in relation to its antimicrobial, antioxidant, anti-inflammatory and central nervous system protective bioactivities.

CONCLUSION

Curcumin is a versatile molecule capable of exerting antimicrobial, antioxidant, anti- inflammatory, and central nervous system protective effects in an enhanced manner using the possibilities offered by the nanotechnology-based approach. Its enhanced bioactivities are associated with increments in solubility, stability, bioavailability, as well as in improved intracellular uptake and cell internalization. These advantages, in addition to curcumin's low toxicity, indicate the potential of curcumin to be loaded and co-loaded into nanosystems capable of providing a controlled release and targeted administration.

Exploration of docetaxel palmitate and its solid lipid nanoparticles as a novel option for alleviating the rising concern of multi-drug resistance

Docetaxel (DTX), a widely prescribed anticancer agent, is now associated with increased instances of multidrug resistance. Also, being a problematic BCS class IV drug, it poses challenges for the formulators. Henceforth, it was envisioned to synthesize an analogue of DTX with a biocompatible lipid, i.e., palmitic acid. The in-silico studies (molecular docking and simulation) inferred lesser binding of docetaxel palmitate (DTX-PL) with P-gp vis-à-vis DTX and paclitaxel, indicating it to be a poor substrate for P-gp efflux. Solid lipid nanoparticles (SLNs) of the conjugate were prepared using various lipids, viz. palmitic acid, stearic acid, cetyl palmitate and glyceryl monostearate. The characterization studies for the nanocarrier were performed for the surface charge, drug payload, micromeritics, release pattern of drug and surface morphology. From the cytotoxicity assays on resistant MCF-7 cells, it was established that the new analogue offered substantially decreased IC₅₀ to that of DTX. Further, apoptosis assay also corroborated the results obtained in IC₅₀ determination wherein, SA-SLNs showed the highest apoptotic index than free DTX. The conjugate not only enhanced the solubility but also offered lower plasma protein binding and improved pharmacokinetic and pharmacodynamic effect for DTX loaded SA-SLNs in apt animal models, and lower affinity to P-gp efflux. The studies provide preliminary evidence and a ray of hope for a better candidate in its nano version for safer and effective cancer chemotherapy.

Current insights on lipid nanocarrier-assisted drug delivery in the treatment of neurodegenerative diseases

The central nervous system (CNS) is vulnerable to pathologic processes that lead to the development of neurodegenerative disorders like Alzheimer's, Parkinson's and Huntington's diseases, Multiple sclerosis or Amyotrophic lateral sclerosis. These are chronic and progressive pathologies characterized by the loss of neurons and the formation of misfolded proteins. Additionally, neurodegenerative diseases are accompanied by a structural and functional dysfunction of the blood-brain barrier (BBB). Although serving as a protection for the CNS, the existence of physiological barriers, especially the BBB, limits the access of several therapeutic agents to the brain, constituting a major hindrance in neurotherapeutics advancement. In this regard, nanotechnology-based approaches have arisen as a promising strategy to not only improve drug targeting to the brain, but also to increase bioavailability. Lipid nanocarriers such as liposomes, solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), microemulsions and nanoemulsions, have already proven their potential for enhancing brain transport, crossing more easily into the CNS and allowing the administration of medicines that could benefit the treatment of neurological pathologies. Given the socioeconomic impact of such conditions and the advent of nanotechnology that inevitably leads to more effective and superior therapeutics for their management, it is imperative to constantly update on the current knowledge of these topics. Herein, we provide insight on the BBB and the pathophysiology of the main neurodegenerative disorders. Moreover, this review seeks to highlight the several approaches that can be used to improve the delivery of therapeutic agents to the CNS, while also offering an extensive overview of the latest efforts regarding the use of lipid-based nanocarriers in the management of neurodegenerative diseases.

Delivery of Docetaxel to Brain Employing Piperine-Tagged PLGA-Aspartic Acid Polymeric Micelles: Improved Cytotoxic and Pharmacokinetic Profiles

In this study, poly-(lactic-co-glycolic) acid (PLGA) was conjugated with aspartic acid and was characterized by nuclear magnetic resonance and Fourier transform infrared spectroscopy. Docetaxel-loaded polymeric micelles were prepared, and piperine was tagged. The neuroblastoma cytotoxicity studies revealed a substantially higher cytotoxic potential of the developed system to that of plain docetaxel, which was further corroborated by cellular uptake employing confocal laser scanning microscopy. The hemocompatible system was able to enhance the pharmacokinetic profile in terms of 6.5-fold increment in bioavailability followed by a 3.5 times increase in the retention time in comparison with the plain drug. The single-point brain bioavailability of docetaxel was amplified by 3.3-folds, signifying a better uptake and distribution to brain employing these carriers. The findings are unique as the physically adsorbed piperine was released before the DTX, increasing the propensity of curbing the CYP3A4 enzyme, which plays a vital role in the degradation of docetaxel. Meanwhile, piperine might have compromised the P-gp efflux mechanism, which can be ascribed to the enhanced retention of the drug at the target site. The elevated target site concentrations and extended residence by a biocompatible nanocarrier supplemented with co-delivery of piperine inherit immense promises to deliver this BCS class IV drug more safely and effectively.

Brain Delivery of Curcumin Using Solid Lipid Nanoparticles and Nanostructured Lipid Carriers: Preparation, Optimization, and Pharmacokinetic Evaluation

Curcumin is a multitherapeutic agent with great therapeutic potential in central nervous system (CNS) diseases. In the current study, curcumin was encapsulated in solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) for the purpose of increasing brain accumulation. The preparation processes have been optimized using experimental design and multiobjective optimization methods. Entrapment efficiency of curcumin in SLNs and NLCs was found to be 82% ± 0.49 and 94% ± 0.74, respectively. The pharmacokinetic studies showed that the amount of curcumin available in the brain was significantly higher in curcumin-loaded NLCs (AUC_0-t = 505.76 ng/g h) compared to free curcumin (AUC_0-t = 0.00 ng/g h) and curcumin-loaded SLNs (AUC_0-t = 116.31 ng/g h) ( P < 0.005), after intravenous (IV) administration of 4 mg/kg dose of curcumin in rat. The results of differential scanning calorimetry and X-ray diffraction showed that curcumin has been dispersed as amorphous in the nanocarriers. Scanning electron microscopy images confirmed the nanoscale size and spherical shape of the nanoparticles. The DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging study indicated that preparation processes do not have any significant effect on the antioxidant activity of curcumin. The results of this study are promising for the use of curcumin-loaded NLCs in more studies and using curcumin in the treatment of CNS diseases.

Oral Delivery of Methylthioadenosine to the Brain Employing Solid Lipid Nanoparticles: Pharmacokinetic, Behavioral, and Histopathological Evidences

The present study aimed to orally deliver methylthioadenosine (MTA) to the brain employing solid lipid nanoparticles (SLNs) for the management of neurological conditions like multiple sclerosis. The stearic acid-based SLNs were below 100 nm with almost neutral zeta potential and offered higher drug entrapment and drug loading. Cuprizone-induced demyelination model in mice was employed to mimic the multiple sclerosis-like conditions. It was observed that the MTA-loaded SLNs were able to maintain the normal metabolism, locomotor activity, motor coordination, balancing, and grip strength of the rodents in substantially superior ways vis-à-vis plain MTA. Histopathological studies of the corpus callosum and its subsequent staining with myelin staining dye luxol fast blue proved the potential of MTA-loaded SLNs in the remyelination of neurons. The pharmacokinetic studies provided the evidences for improved bioavailability and enhanced bioresidence supporting the pharmacodynamic findings. The studies proved that SLN-encapsulated MTA can be substantially delivered to the brain and can effectively remyelinate the neurons. It can reverse the multiple sclerosis-like symptoms in a safer and effective manner, that too by oral route.

Preclinical Explorative Assessment of Dimethyl Fumarate-Based Biocompatible Nanolipoidal Carriers for the Management of Multiple Sclerosis

Multiple sclerosis (MS) is a neurodegenerative disease in which myelin sheath damage occurs due to internal and external factors. MS especially affects the young population. Dimethyl fumarate (DMF) is a promising agent for MS treatment, although it is associated with concerns such as poor brain permeation, multiple dosing, and gastrointestinal flushing. The present study attempts to evaluate the preclinical performance of specially designed DMF-based lipoidal nanoparticles in a cuprizone-induced demyelination model in rodents. The studies proved the efficacy of lipid-based nanoparticles containing DMF in a once-a-day dosage regimen over that of thrice-a-day plain DMF administration on crucial parameters like motor coordination, grip strength, mortality, body weight, and locomotor activity. However, neither blank lipid nor blank neuroprotective (vitamins A, D, and E) loaded nanoparticles were able to elicit any desirable behavioral response. Histopathological studies showed that the designed once-a-day DMF nanomedicines were well tolerated and rejuvenated the myelin sheath vis-à-vis the plain DMF thrice-a-day regimen. These findings provide proof of concept for a biocompatible nanomedicine for MS with tremendous promise for effective brain delivery and patient compliance on the grounds of a reduction in the dosage frequency.

Fullerenol-Based Intracellular Delivery of Methotrexate: A Water-Soluble Nanoconjugate for Enhanced Cytotoxicity and Improved Pharmacokinetics

Derivatization of fullerenes to polyhydroxylated fullerenes, i.e., fullerenols (FLU), dramatically decreases their toxicity and has been reported to enhance the solubility as well as cellular permeability. In this paper, we report synthesis of FLU as nanocarrier and subsequent chemical conjugation of Methotrexate (MTX) to FLU with a serum-stable and intracellularly hydrolysable ester bond between FLU and MTX. The conjugate was characterized for physiochemical attributes, micromeritics, drug-loading, and drug-release and evaluated for cancer cell-toxicity, cellular-uptake, hemocompatibility, protein binding, and pharmacokinetics. The developed hemocompatible FL-MTX offered lower protein binding vis-à-vis naïve drug and substantially higher drug loading. The conjugate offered pH-dependent release of 38.20 ± 1.19% at systemic pH and 85.67 ± 3.39% at the cancer cell pH. FLU-MTX-treated cells showed significant reduction in IC₅₀ value vis-à-vis the cells treated with pure MTX. Analogously, the results from confocal scanning laser microscopy also confirmed the easy access of the dye-tagged FLU-MTX conjugate to the cell interiors. In pharmacokinetics, the AUC of MTX was enhanced by approx. 6.15 times and plasma half-life was enhanced by 2.45 times, after parenteral administration of single equivalent dose in rodents. FLU-MTX offered enhanced availability of drug to the biological system, meanwhile improved the cancer-cell cytotoxicity, sustained the effective plasma drug concentrations, and offered substantial compatibility to erythrocytes.

Recent developments in solid lipid nanoparticle and surface-modified solid lipid nanoparticle delivery systems for oral delivery of phyto-bioactive compounds in various chronic diseases

Solid lipid nanoparticle (SLN) delivery systems have a wide applicability in the delivery of phyto-bioactive compounds to treat various chronic diseases, including diabetes, cancer, obesity and neurodegenerative diseases. The multiple benefits of SLN delivery include improved stability, smaller particle size, leaching prevention and enhanced lymphatic uptake of the bioactive compounds through oral delivery. However, the burst release makes the SLN delivery systems inadequate for the oral delivery of various phyto-bioactive compounds that can treat such chronic diseases. Recently, the surface-modified SLN (SMSLN) was observed to overcome this limitation for oral delivery of phyto-bioactive compounds, and there is growing evidence of an enhanced uptake of curcumin delivered orally via SMSLNs in the brain. This review focuses on different SLN and SMSLN systems that are useful for oral delivery of phyto-bioactive compounds to treat various chronic diseases.

Stearic acid based, systematically designed oral lipid nanoparticles for enhanced brain delivery of dimethyl fumarate

Aim: Dimethyl fumarate is a frequent prescription for the management of numerous neurological disorders. Despite immense promises, DMF is associated with various problems such as multiple dosing (2–3 oral doses daily) and lower brain permeability. Our aim was to enhance the oral bioavailability and increase the brain concentrations of dimethyl fumarate. Methods: Solid lipid nanoparticles were systematically formulated by optimizing the composition based on the desired attributes viz. particle size, entrapment efficiency and amount of drug released in 6 h. Results & conclusion: The developed system offered nanometric particle size with entrapment efficiency > 90%. Enhanced Caco-2 cells cellular uptake by optimized solid lipid nanoparticless with superior pharmacokinetic and higher brain biodistribution were observed.

Evaluation of Brain Pharmacokinetic and Neuropharmacodynamic Attributes of an Antiepileptic Drug, Lacosamide, in Hepatic and Renal Impairment: Preclinical Evidence

The knowledge of pharmacokinetic and pharmacodynamic properties of antiepileptic drugs is helpful in optimizing drug therapy for epilepsy. This study was designed to evaluate the pharmacokinetic and pharmacodynamic properties of lacosamide in experimentally induced hepatic and renal impairment in seizure animals. Hepatic or renal impairment was induced by injection of carbon tetrachloride or diclofenac sodium, respectively. After induction, the animals were administered a single dose of lacosamide. At different time points, maximal electroshock (MES) seizure recordings were made followed by isolation of plasma and brain samples for drug quantification and pharmacodynamic measurements. Our results showed a significant increase in the area under the curve of lacosamide in hepatic and renal impairment groups. Reduced clearance of lacosamide was observed in animals with renal impairment. Along with pharmacokinetic alterations, the changes in pharmacodynamic effects of lacosamide were also observed in all the groups. Lacosamide showed a significant protection against MES-induced seizures, oxidative stress, and neuroinflammatory cytokines. These findings revealed that experimentally induced hepatic or renal impairment could alter the pharmacokinetic as well as pharmacodynamic properties of lacosamide. Hence, these conditions may affect the safety and efficacy of lacosamide.