Evaluation of brain-targeting for the nasal delivery of estradiol by the microdialysis method

Nose-to-Brain (N2B) Delivery: An Alternative Route for the Delivery of Biologics in the Management and Treatment of Central Nervous System Disorders

In recent years, there have been a growing number of small and large molecules that could be used to treat diseases of the central nervous system (CNS). Nose-to-brain delivery can be a potential option for the direct transport of molecules from the nasal cavity to different brain areas. This review aims to provide a compilation of current approaches regarding drug delivery to the CNS via the nose, with a focus on biologics. The review also includes a discussion on the key benefits of nasal delivery as a promising alternative route for drug administration and the involved pathways or mechanisms. This article reviews how the application of various auxiliary agents, such as permeation enhancers, mucolytics, in situ gelling/mucoadhesive agents, enzyme inhibitors, and polymeric and lipid-based systems, can promote the delivery of large molecules in the CNS. The article also includes a discussion on the current state of intranasal formulation development and summarizes the biologics currently in clinical trials. It was noted that significant progress has been made in this field, and these are currently being applied to successfully transport large molecules to the CNS via the nose. However, a deep mechanistic understanding of this route, along with the intimate knowledge of various excipients and their interactions with the drug and nasal physiology, is still necessary to bring us one step closer to developing effective formulations for nasal-brain drug delivery.

Inclusion complexes of the steroid hormones 17β-estradiol and progesterone with β- and γ-cyclodextrin hosts: syntheses, X-ray structures, thermal analyses and API solubility enhancements

Overcoming the challenges of poor aqueous solubility of active pharmaceutical ingredients (APIs) is necessary to render them bioavailable. This study addresses the poor solubility of two potent steroid hormones, 17β-estradiol (BES) and progesterone (PRO), via their complexation with two water-soluble native cyclodextrins (CDs) namely β-CD and γ-CD. The hydrated inclusion complexes β-CD·BES, β-CD·PRO, γ-CD·BES and γ-CD·PRO were prepared via kneading and co-precipitation, and ¹H NMR spectroscopic analysis of solutions of their pure complex crystals yielded the host-guest stoichiometries 2:1, 2:1, 1:1 and 3:2, respectively. Both powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction (SCXRD) were employed for focused studies of the isostructurality of the CD complexes with known complexes and structural elucidation of the new complexes, respectively. SCXRD analyses of β-CD·BES, β-CD·PRO and γ-CD·PRO at 100(2) K yielded the first crystal structures of CD complexes containing the hormones BES and PRO, while the complex γ-CD·BES was readily shown to be isostructural with γ-CD·PRO by PXRD. Severe disorder of the encapsulated steroid molecules in the respective channels of the CD molecular assemblies was evident, however, preventing their modelling, but combination of the host-guest stoichiometries and water contents of the four hydrated inclusion complexes enabled accurate assignment of the chemical formulae of these ternary systems. Predicted electron counts for the complexed molecules BES and PRO correlated reasonably well with the complex compositions indicated by ¹H NMR spectroscopy. Subsequent measurements of the aqueous solubilities of the four complexes confirmed significant solubility improvements effected by encapsulation of the steroids within the CDs, yielding solubility enhancement factors for BES and PRO in the approximate range 5-20.

Restoration of olfactory dysfunctions by nanomaterials and stem cells-based therapies: Current status and future perspectives

Dysfunction in the olfactory system of a person can have adverse effects on their health and quality of life. It can even increase mortality among individuals. Olfactory dysfunction is related to many factors, including post-viral upper respiratory infection, head trauma, and neurodegenerative disorders. Although some clinical therapies such as steroids and olfactory training are already available, their effectiveness is limited and controversial. Recent research in the field of therapeutic nanoparticles and stem cells has shown the regeneration of dysfunctional olfactory systems. Thus, we are motivated to highlight these regenerative approaches. For this, we first introduce the anatomical characteristics of the olfactory pathway, then detail various pathological factors related to olfactory dysfunctions and current treatments, and then finally discuss the recent regenerative endeavors, with particular focus on nanoparticle-based drug delivery systems and stem cells. This review offers insights into the development of future therapeutic approaches to restore and regenerate dysfunctional olfactory systems.

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.

Versatile Nasal Application of Cyclodextrins: Excipients and/or Actives?

Cyclodextrins (CDs) are oligosaccharides widely used in the pharmaceutical field. In this review, a detailed examination of the literature of the last two decades has been made to understand the role of CDs in nasal drug delivery systems. In nasal formulations, CDs are used as pharmaceutical excipients, as solubilizers and absorption promoters, and as active ingredients due to their several biological activities (antiviral, antiparasitic, anti-atherosclerotic, and neuroprotective). The use of CDs in nasal formulations allowed obtaining versatile drug delivery systems intended for local and systemic effects, as well as for nose-to-brain transport of drugs. In vitro and in vivo models currently employed are suitable to analyze the effects of CDs in nasal formulations. Therefore, CDs are versatile pharmaceutical materials, and due to the continual synthesis of new CDs derivatives, the research on the new nasal applications is an interesting field evolving in the coming years, to which Italian research will still contribute.

Intranasal Allopregnanolone Confers Rapid Seizure Protection: Evidence for Direct Nose-to-Brain Delivery

Allopregnanolone, a positive modulator of GABAA receptors with antiseizure activity, has potential in the treatment of seizure emergencies. Instillation of allopregnanolone in 40% sulfobutylether-β-cyclodextrin into the nose in mice rapidly elevated the seizure threshold in the timed intravenous pentylenetetrazol (ED50, 5.6 mg/kg), picrotoxin (ED50, 5.9 mg/kg), and bicuculline seizure tests. The effect peaked at 15 min, decayed over 1 h, and was still evident in some experiments at 6 h. Intranasal allopregnanolone also delayed the onset of seizures in the maximal PTZ test. At an allopregnanolone dose (16 mg/kg) that conferred comparable effects on seizure threshold as the benzodiazepines midazolam and diazepam (both at doses of 1 mg/kg), allopregnanolone caused minimal sedation or motor toxicity in the horizontal screen test whereas both benzodiazepines produced marked behavioral impairment. In addition, intranasal allopregnanolone failed to cause loss-of-righting reflex in most animals, but when the same dose was administered intramuscularly, all animals became impaired. Intranasal allopregnanolone (10 mg/kg) caused a rapid increase in brain allopregnanolone with a Tmax of ~5 min after initiation of the intranasal delivery. High levels of allopregnanolone were recovered in the olfactory bulb (Cmax, 16,000 ng/mg) whereas much lower levels (Cmax, 670 ng/mg) were present in the remainder of the brain. We conclude that the unique ability of intranasal allopregnanolone to protect against seizures without inducing behavioral adverse effects is due in part to direct nose-to-brain delivery, with preferential transport to brain regions relevant to seizures. Benzodiazepines are commonly administered intranasally for acute seizure therapy, including for the treatment of acute repetitive seizures, but are not transported from nose-to-brain. Intranasal allopregnanolone acts with greater speed, has less propensity for adverse effects, and has the ability to overcome benzodiazepine refractoriness. This is the first study demonstrating rapid functional central nervous system activity of a nose-to-brain-delivered steroid. Intranasal delivery circumvents the poor oral bioavailability of allopregnanolone providing a route of administration permitting its evaluation as a treatment for diverse neuropsychiatric indications.

Nanoparticles Based Intranasal Delivery of Drug to Treat Alzheimer's Disease: A Recent Update

Alzheimer Association Report (2019) stated that the 6th primary cause of death in the USA is Alzheimer's Disease (AD), which leads to behaviour and cognitive impairment. Nearly 5.8 million peoples of all ages in the USA have suffered from this disease, including 5.6 million elderly populations. The statistics of the progression of this disease is similar to the global scenario. Still, the treatment of AD is limited to a few conventional oral drugs, which often fail to deliver an adequate amount of the drug in the brain. The reduction in the therapeutic efficacy of an anti-AD drug is due to poor solubility, existence to the blood-brain barrier and low permeability. In this context, nasal drug delivery emerges as a promising route for the delivery of large and small molecular drugs for the treatment of AD. This promising pathway delivers the drug directly into the brain via an olfactory route, which leads to the low systemic side effect, enhanced bioavailability, and higher therapeutic efficacy. However, few setbacks, such as mucociliary clearance and poor drug mucosal permeation, limit its translation from the laboratory to the clinic. The above stated limitation could be overcome by the adaption of nanoparticle as a drug delivery carrier, which may lead to prolong delivery of drugs with better permeability and high efficacy. This review highlights the latest work on the development of promising Nanoparticles (NPs) via the intranasal route for the treatment of AD. Additionally, the current update in this article will draw the attention of the researcher working on these fields and facing challenges in practical applicability.

A novel idea for establishing Parkinson's disease mouse model by intranasal administration of paraquat

Background: In this study, we sought to provide an idea for establishing a novel mouse model for Parkinson's disease (PD) through intranasal administration of paraquat instead of the conventional method of intraperitoneal injection. Intranasal administration has the potential to lower mortality caused by intraperitoneal paraquat administration.Methods: A paraquat-loaded thermosensitive hydrogel composed of poloxamer 407 and poloxamer 188 was prepared. The survival rate of the animals was monitored upon paraquat administration nasally and intraperitoneally. The animals' behavior was also observed. Immunofluorescence staining of tyrosine hydroxylase (TH) - positive cells and western blotting of α-synuclein (α-syn)in striatum were performed. HPLC method with electrochemical detection was used to quantify monoamine neurotransmitters in striatum. Real-time RT-PCR analysis of type 1 collagen, type 3 collagen and fibronectin expression was used to evaluate pulmonary fibrosis in mice after paraquat administration.Results: The results indicated that intranasal administration of paraquat-loaded thermosensitive hydrogel can elicit Parkinsonism-like symptoms in mice. Relative to the conventional intraperitoneal injection, this strategy significantly improves survival when modeling PD and resulted in a higher loss of TH positive neurons in substantia nigra pars compacta (SNpc) and more aggregation of α-syn in striatum. Moreover, animals receiving paraquat hydrogel nasally exhibited motor disorder as well as lower levels of dopamine and dopamine metabolites in striatum when compared to those receiving paraquat intraperitoneally. The mRNA expression of collagen and fibronectinindicated that intranasal administration of paraquat was not associated with lung fibrosis.Conclusion: This strategy provides a new idea and more convenient operation for the future study of mouse model of PD.

A Nasal Temperature and pH Dual-Responsive In Situ Gel Delivery System Based on Microemulsion of Huperzine A: Formulation, Evaluation, and In Vivo Pharmacokinetic Study

Huperzine A (hup A), extracted from the Chinese medicinal plant Huperzia serrata, is a reversible and highly selective second-generation acetylcholine esterase (AchE) inhibitor for treating Alzheimer's disease (AD), but it suffers from low bioavailability in the brain. This study aimed to develop a nasal temperature and pH dual-responsive in situ gel delivery system based on microemulsion of hup A (hup A-M-TPISG). The optimal formulation was obtained by central composite design and response surface methodology. The optimized mucoadhesive formulation, hup A-M-TPISG, was composed of pluronic F127 (20.80%), pluronic F68 (2.8%), and chitosan (0.88%) as the gel matrix, which could gelatinize under physiological conditions (29-34°C, pH 6.5) because of its temperature and pH responsiveness. The optimized hup A-M-TPISG formulation was further evaluated by in vitro release and in vivo pharmacokinetic studies via microdialysis. The in vitro release study showed continuous and steady drug release from hup A-M-TPISG, which was in accordance with the first-order model. Moreover, the pharmacokinetic results revealed that the optimized formulation for nasal administration, with convenient administration and improved patient compliance, could achieve similar brain-targeting properties as intravenous administration. In conclusion, the hup A-M-TPISG for intranasal administration, as an effective and safe vehicle, could enhance the absorption of hup A in vivo and would be a promising noninvasive alternative for partially improving brain-targeting therapy.

Evaluation of intranasal delivery route of drug administration for brain targeting

The acute or chronic drug treatments for different neurodegenerative and psychiatric disorders are challenging from several aspects. The low bioavailability and limited brain exposure of oral drugs, the rapid metabolism, elimination, the unwanted side effects and also the high dose to be added mean both inconvenience for the patients and high costs for the patients, their family and the society. The reason of low brain penetration of the compounds is that they have to overcome the blood-brain barrier which protects the brain against xenobiotics. Intranasal drug administration is one of the promising options to bypass blood-brain barrier, to reduce the systemic adverse effects of the drugs and to lower the doses to be administered. Furthermore, the drugs administered using nasal route have usually higher bioavailability, less side effects and result in higher brain exposure at similar dosage than the oral drugs. In this review the focus is on giving an overview on the anatomical and cellular structure of nasal cavity and absorption surface. It presents some possibilities to enhance the drug penetration through the nasal barrier and summarizes some in vitro, ex vivo and in vivo technologies to test the drug delivery across the nasal epithelium into the brain. Finally, the authors give a critical evaluation of the nasal route of administration showing its main advantages and limitations of this delivery route for CNS drug targeting.

Tanshinol borneol ester on nanostructured lipid carriers has longer brain and systemic effector retention and better antioxidant activity in vivo

Background

Tanshinol borneol ester (DBZ) is a hybrid of danshensu (DSS) and borneol and has anti-ischemic activity in animals. However, its low water solubility and short half-life limit its clinical application.

Methods

We prepared polyethylene glycol (PEG)-modified and DBZ-loaded nanostructured lipid carriers (DBZ-PEG-NLC) and DBZ-NLC, and examined their physical characteristics, such as particle size, zeta potential, entrapment efficiency and drug loading. The in vitro stability and pharmacokinetics in rats as well as antioxidant activity of DBZ-PEG-NLC and DBZ-NLC in a C57BL/6 mouse model of ischemia/reperfusion-related brain injury were investigated. The levels of DBZ and its hydrolyzed DSS in rat plasma and brain microdialysates were determined by liquid chromatography-mass spectroscopy/mass spectroscopy analysis.

Results

We found that the mean particle size and entrapment efficacy of DBZ-PEG-NLC were similar to that of DBZ-NLC. The DBZ-PEG-NLC, like DBZ-NLC, released DBZ in a biphasic manner with initially burst release and then prolonged slow release in vitro. Intravenous injection of DBZ-PEG-NLC resulted in significantly higher levels and longer retention periods of DBZ and DSS in plasma and the brains than DBZ-NLC and DBZ in rats. Finally, treatment with DBZ-PEG-NLC achieved a better antioxidant activity than DBZ or DBZ-NLC in mouse model of ischemia/reperfusion by reducing the levels of brain malondialdehyde, but increasing the levels of brain superoxide dismutase and glutathione.

Conclusion

DBZ-PEG-NLC is a preferable option to deliver DBZ for sustainable release of DSS and borneol in vivo, and may serve as a promising drug for effective therapy of ischemic cardiovascular and cerebrovascular diseases.

Surface-Modified Nanocarriers for Nose-to-Brain Delivery: From Bioadhesion to Targeting

In the field of nasal drug delivery, nose-to-brain delivery is among the most fascinating applications, directly targeting the central nervous system, bypassing the blood brain barrier. Its benefits include dose lowering and direct brain distribution of potent drugs, ultimately reducing systemic side effects. Recently, nasal administration of insulin showed promising results in clinical trials for the treatment of Alzheimer’s disease. Nanomedicines could further contribute to making nose-to-brain delivery a reality. While not disregarding the need for devices enabling a formulation deposition in the nose’s upper part, surface modification of nanomedicines appears the key strategy to optimize drug delivery from the nasal cavity to the brain. In this review, nanomedicine delivery based on particle engineering exploiting surface electrostatic charges, mucoadhesive polymers, or chemical moieties targeting the nasal epithelium will be discussed and critically evaluated in relation to nose-to-brain delivery.

Intranasal delivery of antipsychotic drugs

Antipsychotic drugs are used to treat psychotic disorders that afflict millions globally and cause tremendous emotional, economic and healthcare burdens. However, the potential of intranasal delivery to improve brain-specific targeting remains unrealized. In this article, we review the mechanisms and methods used for brain targeting via the intranasal (IN) route as well as the potential advantages of improving this type of delivery. We extensively review experimental studies relevant to intranasal delivery of therapeutic agents for the treatment of psychosis and mental illnesses. We also review clinical studies in which intranasal delivery of peptides, like oxytocin (7 studies) and desmopressin (1), were used as an adjuvant to antipsychotic treatment with promising results. Experimental animal studies (17) investigating intranasal delivery of mainstream antipsychotic drugs have revealed successful targeting to the brain as suggested by pharmacokinetic parameters and behavioral effects. To improve delivery to the brain, nanotechnology-based carriers like nanoparticles and nanoemulsions have been used in several studies. However, human studies assessing intranasal delivery of mainstream antipsychotic drugs are lacking, and the potential toxicity of nanoformulations used in animal studies has not been explored. A brief discussion of future directions anticipates that if limitations of low aqueous solubility of antipsychotic drugs can be overcome and non-toxic formulations used, IN delivery (particularly targeting specific tissues within the brain) will gain more importance moving forward given the inherent benefits of IN delivery in comparison to other methods.

Intranasal delivery of nanoparticle encapsulated tarenflurbil: A potential brain targeting strategy for Alzheimer's disease

Poor brain penetration of tarenflurbil (TFB) was one of the major reasons for its failure in phase III clinical trials conducted on Alzheimer's patients. Thus there is a tremendous need of developing efficient delivery systems for TFB. This study was designed with the aim of improving drug delivery to brain through intranasally delivered nanocarriers. TFB was loaded into two different nanocarriers i.e., poly (lactide-co-glycolide) nanoparticles (TFB-NPs) and solid lipid nanoparticles (TFB-SLNs). Particle size of both the nanocarriers (<200nm) as determined by dynamic light scattering technique and transmission electron microscopy, assured transcellular transport across olfactory axons whose diameter was ≈200nm and then paving a direct path to brain. TFB-NPs and TFB-SLNs resulted in 64.11±2.21% and 57.81±5.32% entrapment efficiencies respectively which again asserted protection of drug from chemical and biological degradation in nasal cavity. In vitro release studies proved the sustained release of TFB from TFB-NPs and TFB-SLNs in comparison with pure drug, indicating prolonged residence times of drug at targeting site. Pharmacokinetics suggested improved circulation behavior of nanoparticles and the absolute bioavailabilities followed this order: TFB-NPs (i.n.)>TFB-SLNs (i.n.)>TFB solution (i.n.)>TFB suspension (oral). Brain targeting efficiency was determined in terms of %drug targeting efficiency (%DTE) and drug transport percentage (DTP). The higher %DTE (287.24) and DTP (65.18) were observed for TFB-NPs followed by TFB-SLNs (%DTE: 183.15 and DTP: 45.41) among all other tested groups. These encouraging results proved that therapeutic concentrations of TFB could be transported directly to brain via olfactory pathway after intranasal administration of polymeric and lipidic nanoparticles.

The blood-brain barrier and nasal drug delivery to the central nervous system

BACKGROUND

The blood-brain barrier (BBB) is a highly efficient system that separates the central nervous system (CNS) from general circulation and promotes selective transport of molecules that are essential for brain function. However, it also limits the distribution of systemically administered therapeutics to the brain; therefore, there is a restricted number of drugs available for the treatment of brain disorders. Several drug-targeting strategies have been developed to attempt to bypass the BBB, but none has proved sufficiently effective in reaching the brain.

METHODS

The objective of this study is to generally review these strategies of drug administration to the CNS.

RESULTS

Noninvasive methods of drug delivery, such as chemical and biologic transport systems, do not represent a feasible platform, whereas for most drugs, it is still not possible to achieve therapeutic levels within the brain tissue after intravenous or oral administration, and the use of higher potency or more concentrated doses may cause serious toxic side effects. Direct intrathecal drug delivery through a catheter into the CNS also presents several problems. Intranasal drug delivery is a potential alternative method due to the direct transport into the cerebrospinal fluid (CSF) compartment along the olfactory pathway, but the study's conclusions are controversial. An endoscopic intranasal surgical procedure using established skull base surgery reconstruction techniques based on the use of a nasal mucosa surgical flap as the only obstacle between the nose and the subarachnoid space has appeared as a potential solution to increase the absorption of intranasal drugs to the CNS.

CONCLUSION

Despite extensive efforts to develop new techniques to cross the BBB, none has proved sufficiently effective in reaching the brain, whereas minimizing adverse effects and the endoscopic mucosal grafting technique offers new potential promise.

Preparation and evaluation of Baicalin-loaded cationic solid lipid nanoparticles conjugated with OX26 for improved delivery across the BBB

PURPOSE

A novel brain targeting drug delivery system based on OX26 antibody conjugation on PEGylated cationic solid lipid nanoparticles (OX26-PEG-CSLN) was prepared.

METHODS

The Baicalin-loaded PEGylated cationic solid lipid nanoparticles modified by OX26 antibody (OX26-PEG-CSLN) were prepared by emulsion evaporation-solidification at low temperature method. The immune-gold labeled OX26-PEG-CSLN was visualized by transmission electron microscopy. The mean diameter and zeta potential of OX26-PEG-CSLN, PEG-CSLN and CSLN were determined using a Zetasizer. The entrapment efficiency of OX26-PEG-CSLN, PEG-CSLN and CSLN was determined by ultrafiltration centrifugation method. And the solid-state characterization of OX26-PEG-CSLN and CSLN were analyzed by X-ray. Pharmacokinetics studies were conducted by in vivo microdialysis in rat cerebrospinal fluid.

RESULTS

The results showed that the OX26-PEG-CSLN, PEG-CSLN and CSLN had average diameters of 47.68 ± 1.65, 27.20 ± 1.70 and 33.89 ± 5.74 nm, Zeta potentials of -0.533 ± 0.115 mV, 11.200 ± 0.500 mV and 11.080 ± 1.170 mV and entrapment efficiencies of 83.03 ± 0.01%, 92.90 ± 3.50% and 97.83 ± 0.19%, respectively. In the pharmacokinetics studies, the AUC value of OX26-PEG-CSLN was11.08-fold higher than that of the Baicalin solution (SOL) (p<0.01), and 1.12-fold higher than that of the CSLN (p>0.05); the Cmax value of OX26-PEG-CSLN was 7.88-fold higher than that of SOL (p<0.01) and 1.12-fold (p<0.01) higher than that of the CSLN, respectively.

CONCLUSION

These results demonstrated OX26-PEG-CSLN could be a promising carrier to deliver drugs across the BBB for the treatment of brain diseases.

Nanotechnology for CNS delivery of bio-therapeutic agents

The current therapeutic strategies are not efficient in treating disorders related to the central nervous system (CNS) and have only shown partial alleviation of symptoms, as opposed to, disease modifying effects. With change in population demographics, the incidence of CNS disorders, especially neurodegenerative diseases, is expected to rise dramatically. Current treatment regimens are associated with severe side-effects, especially given that most of these are chronic therapies and involve elderly population. In this review, we highlight the challenges and opportunities in delivering newer and more effective bio-therapeutic agents for the treatment of CNS disorders. Bio-therapeutics like proteins, peptides, monoclonal antibodies, growth factors, and nucleic acids are thought to have a profound effect on halting the progression of neurodegenerative disorders and also provide a unique function of restoring damaged cells. We provide a review of the nano-sized formulation-based drug delivery systems and alternate modes of delivery, like the intranasal route, to carry bio-therapeutics effectively to the brain.

PNIPAM nanoparticles for targeted and enhanced nose-to-brain delivery of curcuminoids: UPLC/ESI-Q-ToF-MS/MS-based pharmacokinetics and pharmacodynamic evaluation in cerebral ischemia model

Stroke is a one of the leading causes of disease and deaths worldwide, which causes irreversible deterioration of the central nervous system. Curcuminoids are reported to have a potential role in the amelioration of cerebral ischemia but they exhibit low serum and tissue levels due to low solubility and poor absorption. Curcumin (CUR), demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC)-loaded PNIPAM nanoparticles (NPs) were prepared by free radical polymerization and characterized for particles size, entrapment efficiency, zeta potential, in vitro release and ex vivo permeation study. Optimized CUR, DMC and BDMC-loaded NPs had the mean size of 92.46 ± 2.8, 91.23 ± 4.2 and 94.28 ± 1.91 nm; zeta potential of -16.2 ± 1.42, -15.6 ± 1.33 and -16.6 ± 1.21 mV; loading capacity of 39.31 ± 3.7, 38.91 ± 3.6 and 40.61 ± 3.6% and entrapment efficiency of 84.63 ± 4.2, 84.71 ± 3.99 and 85.73 ± 4.31%, respectively. Ultra-performance liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectroscopy based bioanalytical method was developed and validated for pharmacokinetics, biodistribution, brain-targeting efficiency and brain drug-targeting potential studies post-intranasal (i.n.) administration which showed enhanced bioavailability of curcuminoids in brain as compared to intravenous administration. Improved neurobehavioural activity (locomotor and grip strength) and reduced cytokines levels (TNF-α and IL-1β) was observed in middle cerebral artery occlusion induced cerebral ischemic rats after i.n. administration of curcuminoids NPs. Finally, the toxicity study was performed which revealed safe nature of developed NPs.

Incorporation of beta-sitosterol into the membrane increases resistance to oxidative stress and lipid peroxidation via estrogen receptor-mediated PI3K/GSK3beta signaling

BACKGROUND

Brain lipid peroxidation has long been considered a potential therapeutic target for Alzheimer's disease (AD). beta-sitosterol (BS), a plant sterol that is prevalent in plant plasma membrane, has been suggested to have antioxidant activity. Previous studies have demonstrated that dietary BS can enter the brain and accumulates in the plasma membrane of brain cells. However, it is unknown whether and how BS exerts its antioxidant activity in plasma membrane.

METHODS

To incorporate BS into the plasma membrane in vitro, HT22 cells and primarily cultured hippocampal cells were supplemented with BS using 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD) as a carrier. The present study then tested the antioxidant effect of membrane BS against glucose oxidase (GOX)-induced oxidative stress and lipid peroxidation, and whether the antioxidant effect of membrane BS was associated with estrogen receptor (ER)-mediated phosphatidyl inositol 3-kinase (PL3K)/glycogen synthase kinase 3 (GSK3beta) signaling.

RESULTS

Incorporation of BS into cell membrane prevented GOX-induced oxidative stress and lipid peroxidation, which could be suppressed by the ER antagonists and PI3K inhibitor. Additional experiments showed that incorporation of BS into cell membrane induced an up-regulation of PI3K activity and a recruitment of PI3K to lipid rafts, which could be inhibited by the ER antagonist. Membrane BS also increased the expression of p-GSK3beta, which could be suppressed in the presence of the ER antagonist and PI3K inhibitor.

GENERAL SIGNIFICANCE

Given that BS is prevalent in foods such as plant oil, the results provide a better understanding of the beneficial effects of these BS-enriched nutrients on neurodegenerative diseases such as AD.

Intranasal administration of oxytocin: behavioral and clinical effects, a review

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The mechanisms behind the effects of IN-applied substances need more attention.

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The mechanisms involved in the brain-distribution of IN-OT are completely unexplored.

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The possibly cascading effects of IN-OT on the intrinsic OT-system require serious investigation.

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IN-OT induces clear and specific changes in neural activation.

•

IN-OT is a promising approach to treat certain clinical symptoms.

The intranasal (IN-) administration of substances is attracting attention from scientists as well as pharmaceutical companies. The effects are surprisingly fast and specific. The present review explores our current knowledge about the routes of access to the cranial cavity. ‘Direct-access-pathways’ from the nasal cavity have been described but many additional experiments are needed to answer a variety of open questions regarding anatomy and physiology.

Among the IN-applied substances oxytocin (OT) has an extensive history. Originally applied in women for its physiological effects related to lactation and parturition, over the last decade most studies focused on their behavioral ‘prosocial’ effects: from social relations and ‘trust’ to treatment of ‘autism’.

Only very recently in a microdialysis study in rats and mice, the ‘direct-nose-brain-pathways’ of IN-OT have been investigated directly, implying that we are strongly dependent on results obtained from other IN-applied substances. Especially the possibility that IN-OT activates the ‘intrinsic’ OT-system in the hypothalamus as well needs further clarification.

We conclude that IN-OT administration may be a promising approach to influence human communication but that the existing lack of information about the neural and physiological mechanisms involved is a serious problem for the proper understanding and interpretation of the observed effects.

Development and evaluation of thymoquinone-encapsulated chitosan nanoparticles for nose-to-brain targeting: a pharmacoscintigraphic study

Chitosan (CS) nanoparticles of thymoquinone (TQ) were prepared by the ionic gelation method and are characterized on the basis of surface morphology, in vitro or ex vivo release, dynamic light scattering, and X-ray diffractometry (XRD) studies. Dynamic laser light scattering and transmission electron microscopy confirmed the particle diameter was between 150 to 200 nm. The results showed that the particle size of the formulation was significantly affected by the drug:CS ratio, whereas it was least significantly affected by the tripolyphosphate:CS ratio. The entrapment efficiency and loading capacity of TQ was found to be 63.3% ± 3.5% and 31.23% ± 3.14%, respectively. The drug-entrapment efficiency and drug-loading capacity of the nanoparticles appears to be inversely proportional to the drug:CS ratio. An XRD study proves that TQ dispersed in the nanoparticles changes its form from crystalline to amorphous. This was further confirmed by differential scanning calorimetry thermography. The flat thermogram of the nanoparticle data indicated that TQ formed a molecular dispersion within the nanoparticles. Optimized nanoparticles were evaluated further with the help of scintigraphy imaging, which ascertains the uptake of drug into the brain. Based on maximum concentration, time-to-maximum concentration, area-under-curve over 24 hours, and elimination rate constant, intranasal TQ-loaded nanoparticles (TQ-NP1) proved more effective in brain targeting compared to intravenous and intranasal TQ solution. The high drug-targeting potential and efficiency demonstrates the significant role of the mucoadhesive properties of TQ-NP1.

Airway delivery of peptides and proteins using nanoparticles

Delivery of peptides and proteins via the airways is one of the most exciting potential applications of nanomedicine. These macromolecules could be used for many therapeutic applications, however due to their poor stability in physiological medium and difficulties in delivering them across biological barriers, they are very difficult to use in therapy. Nanoparticulate drug delivery systems have emerged as one of the most promising technologies to overcome these limitations, owing mainly to their proven capacity to cross biological barriers and to enter cells in high yields, thus improving delivery of macromolecules. In this review, we summarize the current advances in nanoparticle designed for transmucosal delivery of peptides and proteins. Challenges that must be overcome in order to derive clinical benefits are also discussed.

Intranasal clobazam delivery in the treatment of status epilepticus

The aim of the present investigation was to prepare and characterize clobazam mucoadhesive microemulsion (CZMME) to assess brain drug uptake and protection against pentylenetetrazole (PTZ)-induced convulsions in mice. Clobazam microemulsion (CZME) and CZMME were prepared by titration method and characterized. Brain uptake and pharmacokinetic parameters were calculated from drug concentration in mice brain versus time plots following intranasal administration of radiolabeled CZME and CZMME, intravenous and intranasal administration of radiolabeled clobazam solution. Gamma scintigraphy imaging of rabbit brain following intranasal administration was performed. Formulations were investigated for the onset of seizures in PTZ-challenged mice. Brain targeting efficiency and direct nose-to-brain transport percentage for mucoadhesive microemulsion suggested an improved brain uptake following intranasal administration. The findings were supported by gamma scintigraphy images. Delay in onset of PTZ-induced seizures with CZMME compared with positive control and placebo-treated groups confirmed the improved brain uptake. However, extensive animal studies followed by clinical trials are necessary to develop a product suitable for emergencies of acute seizures in status epilepticus and patients suffering from drug tolerance and hepatic impairment on long-term use in treatment of epilepsy, schizophrenia, and anxiety.

2-hydroxypropyl-beta-cyclodextrin raises hearing threshold in normal cats and in cats with Niemann-Pick type C disease

2-hydroxypropyl-beta-cyclodextrin (HPbetaCD) is a promising experimental therapy for Niemann-Pick type C disease that improved intracellular cholesterol transport, substantially reduced neurodegeneration and hepatic disease, and increased lifespan in npc1 mice. On the basis of favorable treatment outcome in mice, HPbetaCD is being evaluated as a therapy in children with Niemann-Pick type C (NPC) disease. We evaluated the efficacy of HPbetaCD in the feline model of NPC disease and recognized a dose-dependent increase in hearing threshold associated with therapy as determined by brain stem auditory evoked response (BAER) testing. To further assess the effect of HPbetaCD on hearing threshold, normal cats were administered the drug s.c. at either 4000 mg/kg or 8000 mg/kg body weight, or intrathecally at a dose of 4000 mg/kg brain weight. HPbetaCD caused a significant increase in hearing threshold following one dose of 8000 mg/kg s.c. or 120 mg intrathecally, and the effect was maintained for at least 12 weeks. Repeated weekly s.c. administration of 4000 mg/kg HPbetaCD resulted in a similar increase in hearing threshold. These studies are the first to describe a specific negative effect of HPbetaCD on the auditory system and suggest the need for auditory testing in patients receiving similar doses of HPbetaCD.

Intranasal delivery to the central nervous system: mechanisms and experimental considerations

The blood-brain barrier (BBB) limits the distribution of systemically administered therapeutics to the central nervous system (CNS), posing a significant challenge to drug development efforts to treat neurological and psychiatric diseases and disorders. Intranasal delivery is a noninvasive and convenient method that rapidly targets therapeutics to the CNS, bypassing the BBB and minimizing systemic exposure. This review focuses on the current understanding of the mechanisms underlying intranasal delivery to the CNS, with a discussion of pathways from the nasal cavity to the CNS involving the olfactory and trigeminal nerves, the vasculature, the cerebrospinal fluid, and the lymphatic system. In addition to the properties of the therapeutic, deposition of the drug formulation within the nasal passages and composition of the formulation can influence the pathway a therapeutic follows into the CNS after intranasal administration. Experimental factors, such as head position, volume, and method of administration, and formulation parameters, such as pH, osmolarity, or inclusion of permeation enhancers or mucoadhesives, can influence formulation deposition within the nasal passages and pathways followed into the CNS. Significant research will be required to develop and improve current intranasal treatments and careful consideration should be given to the factors discussed in this review.

Various drug delivery approaches to the central nervous system

IMPORTANCE OF THE FIELD

The presence of the blood-brain barrier (BBB), an insurmountable obstacle, in particular, and other barriers in brain and periphery contribute to hindrance of the successful diagnosis and treatment of a myriad of central nervous system pathologies. This review discusses several strategies adopted to define a rational drug delivery approach to the CNS along with a short description of the strategies implemented by the authors' group to enhance the analgesic activity, a CNS property, of chimeric peptide of Met-enkephalin and FMRFa (YGGFMKKKFMRFa-YFa).

AREAS COVERED IN THIS REVIEW

Various approaches for drug delivery to the CNS with their beneficial and non-beneficial aspects, supported by an extensive literature survey published recently, up to August 2009.

WHAT THE READER WILL GAIN

The reader will have the privilege of gaining an understanding of previous as well as recent approaches to breaching the CNS barriers.

TAKE HOME MESSAGE

Among the various strategies discussed, the potential for efficacious CNS drug targeting in future lies either with the non-invasively administered multifunctional nanosystems or these nanosystems without characterstics such as long systemic circulating capability and avoiding reticuloendothelial system scavenging system of the body, endogenous transporters and efflux inhibitors administered by convection-enhanced delivery.

Getting into the brain: approaches to enhance brain drug delivery

Being the most delicate organ of the body, the brain is protected against potentially toxic substances by the blood-brain barrier (BBB), which restricts the entry of most pharmaceuticals into the brain. The developmental process for new drugs for the treatment of CNS disorders has not kept pace with progress in molecular neurosciences because most of the new drugs discovered are unable to cross the BBB. The clinical failure of CNS drug delivery may be attributed largely to a lack of appropriate drug delivery systems. Localized and controlled delivery of drugs at their desired site of action is preferred because it reduces toxicity and increases treatment efficiency. The present review provides an insight into some of the recent advances made in the field of brain drug delivery.The various strategies that have been explored to increase drug delivery into the brain include (i) chemical delivery systems, such as lipid-mediated transport, the prodrug approach and the lock-in system; (ii) biological delivery systems, in which pharmaceuticals are re-engineered to cross the BBB via specific endogenous transporters localized within the brain capillary endothelium; (iii) disruption of the BBB, for example by modification of tight junctions, which causes a controlled and transient increase in the permeability of brain capillaries; (iv) the use of molecular Trojan horses, such as peptidomimetic monoclonal antibodies to transport large molecules (e.g. antibodies, recombinant proteins, nonviral gene medicines or RNA interference drugs) across the BBB; and (v) particulate drug carrier systems. Receptor-mediated transport systems exist for certain endogenous peptides, such as insulin and transferrin, enabling these molecules to cross the BBB in vivo.The use of polymers for local drug delivery has greatly expanded the spectrum of drugs available for the treatment of brain diseases, such as malignant tumours and Alzheimer's disease. In addition, various drug delivery systems (e.g. liposomes, microspheres, nanoparticles, nanogels and bionanocapsules) have been used to enhance drug delivery to the brain. Recently, microchips and biodegradable polymers have become important in brain tumour therapy.The intense search for alternative routes of drug delivery (e.g. intranasal drug delivery, convection-enhanced diffusion and intrathecal/intraventricular drug delivery systems) has been driven by the need to overcome the physiological barriers of the brain and to achieve high drug concentrations within the brain. For more than 30 years, considerable efforts have been made to enhance the delivery of therapeutic molecules across the vascular barriers of the CNS. The current challenge is to develop drug delivery strategies that will allow the passage of drug molecules through the BBB in a safe and effective manner.

Dopaminergic and serotonergic activity in neostriatum and nucleus accumbens enhanced by intranasal administration of testosterone

Testosterone was administered intranasally in anesthetized male rats, and its effects on the activity of dopaminergic and serotonergic neurons in the neostriatum and nucleus accumbens were assessed by means of microdialysis and HPLC. The treatment (0.5, 1.0 or 2.0 mg/kg of testosterone or vehicle, 10 microl volume) was applied in both nostrils, half (5 microl) into each. Subcutaneous injections of testosterone (2.0, 4.0 or 8.0 mg/kg) or vehicle were tested in other subjects. Samples were collected for 5 h. In the neostriatum, an increase of dopamine occurred after 2.0 mg/kg. Serotonin levels increased after 1.0 mg/kg dose. In the nucleus accumbens, dopamine and serotonin increased after 1.0 mg/kg and 2.0 mg/kg doses. Subcutaneous administration of 8.0 mg/kg testosterone increased dopamine and serotonin in the neostriatum only. We conclude that intranasal administration of testosterone is a more efficacious way for targeting the brain than the subcutaneous route, and may be considered as a means to activate central dopaminergic and serotonergic systems.

Intranasal administration of progesterone increases dopaminergic activity in amygdala and neostriatum of male rats

We evaluated the effects of intranasal administration of progesterone (PROG) on the activity of dopaminergic neurons in the brain of anesthetized rats by means of microdialysis. Male Wistar rats were implanted with guide cannulae in the basolateral amygdala and neostriatum. Three to 5 days later, they were anesthetized with urethane, and dialysis probes were inserted. After a stabilization period of 2 h, four 30-min samples were collected. Thereafter, the treatment (0.5, 1.0 or 2.0 mg/kg of PROG dissolved in a viscous castor oil mixture, or vehicle) was applied into the nose in a volume of 10 microl (5 microl in each nostril). In other animals, an s.c. injection of PROG (1.0, 2.0 or 4.0 mg/kg) or vehicle was given. Samples of both application ways were collected at 30-min interval for 4 h after the treatment and immediately analyzed with high performance liquid chromatography and electrochemical detection. Intranasal administration of 2 mg/kg of PROG led to an immediate (within 30 min after the treatment) significant increase in the basolateral amygdala dopamine levels. In the neostriatum, the 2 mg/kg dose led to a delayed significant increase in dopamine. S.c. administration of 4 mg/kg of PROG was followed by a delayed significant increase in dopamine, both, in the basolateral amygdala and neostriatum, but smaller in magnitude in comparison to the intranasal treatment. This is the first study to demonstrate dopamine-enhancing effects of PROG, not only in the neostriatum, but also in the basolateral amygdala. Our results indicate that the intranasal route of administration of PROG is a more efficacious way for targeting the brain than the s.c. route.

Progress in drug delivery to the central nervous system by the prodrug approach

This review describes specific strategies for targeting to the central nervous system (CNS). Systemically administered drugs can reach the brain by crossing one of two physiological barriers resistant to free diffusion of most molecules from blood to CNS: the endothelial blood-brain barrier or the epithelial blood-cerebrospinal fluid barrier. These tissues constitute both transport and enzymatic barriers. The most common strategy for designing effective prodrugs relies on the increase of parent drug lipophilicity. However, increasing lipophilicity without a concomitant increase in rate and selectivity of prodrug bioconversion in the brain will result in failure. In these regards, consideration of the enzymes present in brain tissue and in the barriers is essential for a successful approach. Nasal administration of lipophilic prodrugs can be a promising alternative non-invasive route to improve brain targeting of the parent drugs due to fast absorption and rapid onset of drug action. The carrier-mediated absorption of drugs and prodrugs across epithelial and endothelial barriers is emerging as another novel trend in biotherapeutics. Several specific transporters have been identified in boundary tissues between blood and CNS compartments. Some of them are involved in the active supply of nutrients and have been used to explore prodrug approaches with improved brain delivery. The feasibility of CNS uptake of appropriately designed prodrugs via these transporters is described in detail.

Intranasal dopamine application increases dopaminergic activity in the neostriatum and nucleus accumbens and enhances motor activity in the open field

Dopamine (DA) plays an important role in a number of behavioral processes and neurological disorders. The intranasal administration of DA provides improved brain penetrability in comparison to systemic administration. We investigated the effects of intranasal administration of DA on the activity of dopaminergic neurons of the mesostriatal and mesolimbic systems and on motor activity. Rats previously implanted with guide-cannulae in the neostriatum (NS) and nucleus accumbens (NAc) were submitted to microdialysis procedure under urethane anesthesia. Vehicle or DA (0.03, 0.3, or 3.0 mg/kg) was administered bilaterally into the nostrils. In a separate study, animals received an intraperitoneal (i.p.) injection of vehicle or DA (0.03, 0.3, 3.0, or 30.0 mg/kg). Samples were collected every 10 min and analyzed for the content of DA and metabolites using high-performance liquid chromatography. For the open field study, rats were given intranasal vehicle or DA (0.03, 0.3, or 3.0 mg/kg) and placed into the field for 30 min. Motor activity (locomotion and rearing) and grooming were analyzed in blocks of 10 min using Ethovision. Intranasal DA (3.0 mg/kg) significantly increased DA levels in the NS and NAc immediately after administration. A comparable effect was obtained only after i.p. administration of 30 mg/kg DA. In the open field, the 3.0 mg/kg dose significantly decreased grooming behavior in the second 10 min interval and significantly increased locomotor activity in the third 10 min interval. The data indicate that intranasal administration of DA can influence dopaminergic functions and motor activity, and has a potential application in the therapy of diseases affecting the dopaminergic system.