Brain distribution of ribavirin after intranasal administration

Ribavirin has proved to be effective in vitro against several RNA viruses responsible for encephalitis in humans and animals. However, the in vivo efficacy towards the cerebral viral load seems to be limited by the blood–brain barrier. Since the nose-to-brain pathway has been indicated for delivering drugs to the brain, we investigated here the distribution of ribavirin in the central nervous system (CNS) after intranasal administration. We first tested in vitro ribavirin diffusion from an aqueous solution across a biological membrane, using Franz cells and rabbit nasal mucosa. About 35% of ribavirin permeated in 4 h across the mucosa, after reaching steady-state flux in less than 30 min. In the first in vivo experiment, ribavirin aqueous solution was administered intranasally to Sprague Dawley rats (10 mg/kg). Animals were sacrificed at 10, 20 or 30 min after administration to collect brain areas (cerebellum, olfactory bulb, cerebral cortex, basal ganglia and hippocampus) and biological fluids (cerebrospinal fluid and plasma). Ribavirin, quantified by LC–MS/MS spectrometry, was detected at each time point in all compartments with the highest concentration in olfactory bulb and decreasing in rostro-caudal direction. Two subsequent in vivo experiments compared the nasal route (ribavirin solution) with the intravenous one and the nasal administration of ribavirin solution with ribavirin powder (10 mg/kg). It was found that 20 min after administration, ribavirin concentration in olfactory bulb was similar after intravenous or nasal administration of the ribavirin solution, whereas the powder led to significantly higher levels. Ribavirin was also present in deeper compartments, such as basal ganglia and hippocampus.Even if the mechanisms involved in ribavirin nose-to-brain transport are not clear, these results suggest a rapid extracellular diffusive flux from the nasal epithelium to the olfactory bulb and different CNS areas.     

神经毒素-I纳米粒鼻腔给药的脑内递送研究

许多分子质量较大的药物如肽类、蛋白质、基因和抗生素等很难通过血脑屏障(blood brain barrier,BBB).进入脑内发挥作用[1,2].常用于提高脑内药物浓度的方法有局部脑室植入、利用高渗溶液或血管活性物质增加BBB开放等[3],但这些方法具有一定损伤性,仅适用于短期治疗药物.     

Role of mucoadhesive polymers in enhancing delivery of nimodipine microemulsion to brain via intranasal route

Intranasal drug administration is receiving increased attention as a delivery method for bypassing the blood–brain barrier and rapidly targeting therapeutics to the CNS. However, rapid mucociliary clearance in the nasal cavity is a major hurdle. The purpose of this study was to evaluate the effect of mucoadhesive polymers in enhancing the delivery of nimodipine microemulsion to the brain via the intranasal route. The optimized mucoadhesive microemulsion was characterized, and the in vitro drug release and in vivo nasal absorption of drug from the new formulation were evaluated in rats. The optimized formulation consisted of Capmul MCM as oil, Labrasol as surfactant, and Transcutol P as co-surfactant, with a particle size of 250 nm and zeta potential value of −15 mV. In vitro and ex vivo permeation studies showed an initial burst of drug release at 30 min and sustained release up to 6 h, attributable to the presence of free drug entrapped in the mucoadhesive layer. In vivo pharmacokinetic studies in rats showed that the use of the mucoadhesive microemulsion enhanced brain and plasma concentrations of nimodipine. These results suggest that incorporation of a mucoadhesive agent in a microemulsion intranasal delivery system can increase the retention time of the formulation and enhance brain delivery of drugs.KEY WORDS: Blood–brain barrier, Entrapment, Permeation, Pharmacokinetics, Nasal mucosa     

In vivo nose-to-brain delivery of the hydrophilic antiviral ribavirin by microparticle agglomerates

Nasal administration has been proposed as a potential approach for the delivery of drugs to the central nervous system. Ribavirin (RBV), an antiviral drug potentially useful to treat viral infections both in humans and animals, has been previously demonstrated to attain several brain compartments after nasal administration. Here, a powder formulation in the form of agglomerates comprising micronized RBV and spray-dried microparticles containing excipients with potential absorption enhancing properties, i.e. mannitol, chitosan, and α-cyclodextrin, was developed for nasal insufflation. The agglomerates were characterized for particle size, agglomeration yield, and ex vivo RBV permeation across rabbit nasal mucosa as well as delivery from an animal dry powder insufflator device. Interestingly, permeation enhancers such as chitosan and mannitol showed a lower amount of RBV permeating across the excised nasal tissue, whereas α-cyclodextrin proved to outperform the other formulations and to match the highly soluble micronized RBV powder taken as a reference. In vivo nasal administration to rats of the agglomerates containing α-cyclodextrin showed an overall higher accumulation of RBV in all the brain compartments analyzed as compared with the micronized RBV administered as such without excipient microparticles. Hence, powder agglomerates are a valuable approach to obtain a nasal formulation potentially attaining nose-to-brain delivery of drugs with minimal processing of the APIs and improvement of the technological and biopharmaceutical properties of micronized API and excipients, as they combine optimal flow properties for handling and dosing, suitable particle size for nasal deposition, high surface area for drug dissolution, and penetration enhancing properties from excipients such as cyclodextrins.     

经鼻脑靶向递药系统的研究进展

鼻腔与脑在解剖生理上的独特联系使得鼻腔给药作为脑内递药途径成为可能.鼻腔给药作为脑靶向的途径之一,可有效地使通过其他给药途径不易透过血脑屏障的药物绕过血脑屏障到达脑部,为中枢神经系统疾病的治疗提供了一种极有发展前景的脑内递药途径.就鼻腔给药脑靶向的依据、影响因素、评价方法、剂型等方面对经鼻脑靶向递药系统的研究现状进行总结.     

Brain targeting studies on buspirone hydrochloride after intranasal administration of mucoadhesive formulation in rats

Objectives The purpose of this study was to find out whether nasal application of buspirone could increase its bioavailability and directly transport the drug from nose to brain. Methods A nasal formulation (Bus‐chitosan) was prepared by dissolving 15.5 mg buspirone hydrochloride, 1% w/v chitosan hydrochloride and 5% w/v hydroxypropyl β‐cyclodextrin (HP‐β‐CD) in 5 ml of 0.5% sodium chloride solution. The formulation was nasally administered to rats and the plasma and brain concentration compared with that for buspirone hydrochloride solution after intravenous and intranasal (Bus‐plain) administration. The brain drug uptake was also confirmed by gamma scintigraphic study. Key findings The nasal Bus‐chitosan formulation improved the absolute bioavailability to 61% and the plasma concentration peaked at 30 min whereas the peak for nasal Bus‐plain formulation was 60 min. The AUC_0‐480 in brain after nasal administration of Bus‐chitosan formulation was 2.5 times that obtained by intravenous administration (711 ± 252 ng/g vs 282 ± 110 ng/g); this was also considerably higher than that obtained with the intranasal Bus‐plain formulation (354 ± 80 ng/g). The high percentage of direct drug transport to the brain (75.77%) and high drug targeting index (>1) confirmed the direct nose to brain transport of buspirone following nasal administration of Bus‐chitosan formulation. Conclusions These results conclusively demonstrate increased access of buspirone to the blood and brain from intranasal solution formulated with chitosan and HP‐β‐CD.     

Transfer of morphine along the olfactory pathway to the central nervous system after nasal administration to rodents

The aim of this study was to investigate whether morphine can be transferred along the olfactory pathway to the CNS, thereby circumventing the blood–brain barrier, after nasal administration to rodents. Radiolabelled and unlabelled morphine were administered via the right nostril to mice and rats. Olfactory bulbs, brain tissue and blood samples were collected. Morphine-derived radioactivity was measured using liquid scintillation (LS) and the concentrations of morphine and its metabolite morphine-3-glucuronide (M3G) were also assessed with high-performance liquid chromatography. The location of morphine-derived radioactivity in the rat brain was visualised by autoradiography. Overall, the levels of morphine in the right olfactory bulbs (ROBs) significantly exceeded those in the left olfactory bulbs (LOBs) and brain tissue samples 15, 60 and 240 min after right-sided nasal administration. Fifteen minutes after intravenous administration, there were no significant differences between olfactory bulbs and the other brain areas. Five minutes after nasal administration, autoradiography revealed radioactivity surrounding the ROB and reaching one of the ventricles in the brain. After 60 min, radioactivity had reached the peripheral parts of the ROB. All the techniques used in this study demonstrate that morphine was transferred along the olfactory pathway to the CNS after nasal administration to rodents.     

Delivery of 125I-cobrotoxin after intranasal administration to the brain: a microdialysis study in freely moving rats

In order to determine the contribution of intranasal (i.n.) administration to the uptake of large molecular weight (MW) substances into central nervous system (CNS), concentration in brain of the centrally acting polypeptide cobrotoxin (NT-I) versus time profiles were studied using dual-probe microdialysis in awake free-moving rats. NT-I, radiolabeled with sodium (125)I-Iodide ((125)I-NT-I), was administered at the dose of 105 microg/kg intravenously and intranasally in the same set of rat (n=15). The (125)I-NT-Inasal preparations were formulated with borneol/menthol eutectic mixture (+BMEM) as an absorption enhancer and without (-BMEM). After application, the dialysates sampled simultaneously from olfactory bulb and cerebellar nuclei were measured in a gamma-counter for radioactivity. The real concentrations of NT-I were recalculated by in vivo recoveries of microdialysis probes. The results showed that the area under the curve (AUC) value in cerebellar nuclei (2283.51+/-34.54 min ng/ml) following i.n. administration (+BMEM) was significantly larger than those (AUC(olfactory)=1141.92+/-26.42 min ng/ml; AUC(cerebellar)=1364.62+/-19.35 min ng/ml) after intravenous (i.v.) bolus, respectively. A prolonged time values to peak concentrations after i.n. application (+BMEM) were observed compared with those following i.v. administration. Also, following i.n. application (+BMEM) the measured time value to peak concentration in cerebellar nuclei (85 min) was statistically longer than that in olfactory bulb (75 min), which could be plausibly an indication for NT-I delivery into brain via nose-brain pathway in the presence of absorption enhancer. i.n. administration (-BMEM) had little or no ability of NT-I delivering into brain. In conclusion, i.n. administration (+BMEM) significantly enhanced brain transport of NT-I with uneven distribution in discrete regions of brain compared with i.v. administration. Additionally, multi-probe microdialysis technique should be considerably valuable in brain delivery studies.     

Polymeric nanocarriers for nose-to-brain drug delivery in neurodegenerative diseases and neurodevelopmental disorders

Neurodegenerative diseases are progressive conditions that affect the neurons of the central nervous system(CNS) and result in their damage and death. Neurodevelopmental disorders include intellectual disability, autism spectrum disorder, and attention-deficit/hyperactivity disorder and stem from the disruption of essential neurodevelopmental processes. The treatment of neurodegenerative and neurodevelopmental conditions, together affecting ～120 million people worldwide, is challenged by the blo...     

Co-delivery of doxorubicin and siRNA for glioma therapy by a brain targeting system: angiopep-2-modified poly(lactic-co-glycolic acid) nanoparticles

It is very challenging to treat brain cancer because of the blood–brain barrier (BBB) restricting therapeutic drug or gene to access the brain. In this research project, angiopep-2 (ANG) was used as a brain-targeted peptide for preparing multifunctional ANG-modified poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs), which encapsulated both doxorubicin (DOX) and epidermal growth factor receptor (EGFR) siRNA, designated as ANG/PLGA/DOX/siRNA. This system could efficiently deliver DOX and siRNA into U87MG cells leading to significant cell inhibition, apoptosis and EGFR silencing in vitro. It demonstrated that this drug system was capable of penetrating the BBB in vivo, resulting in more drugs accumulation in the brain. The animal study using the brain orthotopic U87MG glioma xenograft model indicated that the ANG-targeted co-delivery of DOX and EGFR siRNA resulted in not only the prolongation of the life span of the glioma-bearing mice but also an obvious cell apoptosis in glioma tissue.     

N‐Malonyl‐1,2‐dihydroisoquinoline as a Novel Carrier for Specific Delivery of Drugs to the Brain

N‐Malonyl‐1,2‐dihydroisoquinoline derivatives were synthesized and investigated as a novel carrier system for site‐specific and sustained delivery of drugs to the brain. Such carriers are expected to be stable against air oxidation due to the presence of the carbonyl group close to nitrogen of the dihydroisoquinoline. Reduction of the prepared isoquinolinium quaternary derivatives with sodium dithionite afforded a novel group of N‐malonyl‐1,2‐dihydroisoquinoline chemical delivery systems (CDS). The synthesized N‐malonyl‐1,2‐dihydroisoquinoline chemical delivery systems were subjected to various chemical and biological investigations to evaluate their ability to cross the blood‐brain barrier (BBB), and to be oxidized biologically into their corresponding quaternary derivatives. The in‐vitro oxidation studies showed that the designed N‐malonyl‐1,2‐dihydroisoquinoline chemical delivery system could be oxidized into its corresponding quaternary derivatives at an adequate rate. The in‐vivo distribution studies showed that these N‐malonyl‐1,2‐dihydroisoquinoline chemical delivery systems were able to cross the blood‐brain barrier at detectable concentrations.     

Manipulation of olfactory tight junctions using papaverine to enhance intranasal delivery of gemcitabine to the brain

Abstract

Context: Delivery of drugs from the nasal cavity to the brain is becoming more widely accepted, due to the non-invasive nature of this route and the ability to circumvent the blood brain barrier (BBB).

Objective: Because of similarities in the proteins comprising the olfactory epithelial tight junction (TJ) proteins and those of the BBB, we sought to determine whether papaverine (PV), which is known to reversibly enhance BBB permeability, could increase the delivery of intranasally administered gemcitabine to the central nervous system in rats.

Experimental methods: Included intranasal administration of gemcitabine, fluorescein isothiocyanate-dextran beads and PV, histopathology, immunostaining, RT-PCR, western blot analysis, immunofluorescence localization, spectrofluorometric analysis, in vivo brain microdialysis, HPLC analysis and in vitro gemcitabine recovery.

Results and discussion: PV transiently decreased the levels and altered immunolocalization of the TJ protein phosphorylated-occludin in the olfactory epithelium, while causing an approximately four-fold increase in gemcitabine concentration reaching the brain. The enhanced delivery was not accompanied by nasal epithelial damage or toxicity to distant organs.

Conclusions: The ability to transiently and safely increase drug delivery from the nose to the brain represents a non-invasive way to improve treatment of patients with brain disorders.     

脑靶向空间稳定免疫脂质体研究进展

介绍了脑靶向空间稳定免疫脂质体制剂的研究进展。大部分药物因其水溶性或分子质量超过500u无法透过血脑屏障，而脑靶向空间稳定免疫脂质体能将治疗药物通过相关单抗主动靶向脑部，从而提高脑内药物浓度，降低毒副作用。     

Nano carriers for drug transport across the blood–brain barrier

Effective therapy lies in achieving a therapeutic amount of drug to the proper site in the body and then maintaining the desired drug concentration for a sufficient time interval to be clinically effective for treatment. The blood–brain barrier (BBB) hinders most drugs from entering the central nervous system (CNS) from the blood stream, leading to the difficulty of delivering drugs to the brain via the circulatory system for the treatment, diagnosis and prevention of brain diseases. Several brain drug delivery approaches have been developed, such as intracerebral and intracerebroventricular administration, intranasal delivery and blood-to-brain delivery, as a result of transient BBB disruption induced by biological, chemical or physical stimuli such as zonula occludens toxin, mannitol, magnetic heating and ultrasound, but these approaches showed disadvantages of being dangerous, high cost and unsuitability for most brain diseases and drugs. The strategy of vector-mediated blood-to-brain delivery, which involves improving BBB permeability of the drug–carrier conjugate, can minimize side effects, such as being submicrometre objects that behave as a whole unit in terms of their transport and properties, nanomaterials, are promising carrier vehicles for direct drug transport across the intact BBB as a result of their potential to enter the brain capillary endothelial cells by means of normal endocytosis and transcytosis due to their small size, as well as their possibility of being functionalized with multiple copies of the drug molecule of interest. This review provids a concise discussion of nano carriers for drug transport across the intact BBB, various forms of nanomaterials including inorganic/solid lipid/polymeric nanoparticles, nanoemulsions, quantum dots, nanogels, liposomes, micelles, dendrimers, polymersomes and exosomes are critically evaluated, their mechanisms for drug transport across the BBB are reviewed, and the future directions of this area are fully discussed.     

冰片对克林霉素透过小鼠血-脑脊液屏障的促进作用

目的 建立高效液相色谱-质谱联用（LC/MS）定量分析方法测定小鼠脑组织中的克林霉素,采用正交实验设计分析不同剂量冰片在不同时间促进克林霉素的跨血-脑脊液屏障作用. 方法 灌胃给予小鼠0,150,300,600 mg•kg^-1冰片溶液（PEG400溶解）,尾静脉注射克林霉素磷酸酯溶液40 mg•kg^-1,分别在15,30,45 min取样,脑组织匀浆样品经碱化醋酸乙酯提取后氮吹浓缩,采用双通道选择性离子抽提测定克林霉素和内标枸橼酸芬太尼,克林霉素和枸橼酸芬太尼的选择检测离子分别为m/z 425.20（［M+H］⁺）、m/z 337.30（［M+H］⁺）. 结果 该法可准确测定脑组织中克林霉素的浓度. 300 mg•kg^-1冰片灌胃在30 min时克林霉素在脑组织中的浓度较高与对照组比较差异有显著性. 结论 该分析方法准确、快速、专一性好. 冰片可以促进克林霉素进入脑组织.     

From blood to brain: blood cell-based biomimetic drug delivery systems

Brain drug delivery remains a major difficulty for several challenges including the blood–brain barrier, lesion spot targeting, and stability during circulation. Blood cells including erythrocytes, platelets, and various subpopulations of leukocytes have distinct features such as long-circulation, natural targeting, and chemotaxis. The development of biomimetic drug delivery systems based on blood cells for brain drug delivery is growing fast by using living cells, membrane coating nanotechnology, or cell membrane-derived nanovesicles. Blood cell-based vehicles are superior delivery systems for their engineering feasibility and versatile delivery ability of chemicals, proteins, and all kinds of nanoparticles. Here, we focus on advances of blood cell-based biomimetic carriers for from blood to brain drug delivery and discuss their translational challenges in the future.     

脑靶向给药系统研究进展

血-脑屏障阻碍药物进入脑组织,不利于中枢神经系统疾病的治疗.本文介绍了近年来脑靶向给药系统的研究进展,包括通过受体(如载脂蛋白受体、转铁蛋白受体等)介导的主动靶向系统、被动靶向系统(如纳米粒、碳纳米管等)及其他靶向系统(如磁性微粒、阳离子制剂等).     

卡巴拉汀脂质体的制备及其大鼠鼻腔给药的药代动力学

制备卡巴拉汀脂质体,研究其在大鼠鼻腔给药的药代动力学。采用硫酸铵梯度法制备包载卡巴拉汀的脂质体,考察粒径、zeta电位和包封率,测定脂质体在磷酸盐缓冲液中的释放;大鼠鼻腔给予卡巴拉汀脂质体,以安替比林为内标,采用高效液相色谱-串联质谱法(HPLC/MS)测定血浆中卡巴拉汀的浓度,运用DAS 2.0软件拟合药代动力学参数。经筛选制备的脂质体包封率为(33.41±6.58)%,平均粒径在154～236 nm,zeta电位(-10.47±2.41)mV。脂质体的体外释放符合一级动力学方程。大鼠鼻腔给药后,Cmax,Tmax和AUC0-∞分别为(1.50±0.15)mg.L-1,15 min和(89.06±8.30)mg.L-1.min。卡巴拉汀制备成脂质体经大鼠鼻腔给药后,吸收迅速,血药浓度可以达到一定水平。     

Selective plasma pharmacokinetics and brain uptake in the mouse of enzyme fusion proteins derived from species-specific receptor-targeted antibodies

Enzymes may be re-engineered for brain drug targeting as an IgG-enzyme fusion protein, where the IgG is a monoclonal antibody (MAb) against an endogenous blood–brain barrier (BBB) receptor transporter, such as the insulin receptor or transferrin receptor (TfR). Iduronate 2-sulfatase (IDS) is fused to the heavy chain of a genetically engineered MAb against the human insulin receptor (HIR). Neither the HIRMAb alone, nor the HIRMAb–IDS fusion protein, is delivered across the BBB in the mouse, owing to lack of cross-reactivity of the HIRMAb with the insulin receptor in the mouse. The uptake of the HIRMAb–IDS fusion protein in peripheral organs exceeds that of the HIRMAb, which is attributed to uptake mediated via the mannose-6 phosphate receptor in non-brain organs. In contrast to the lack of BBB transport of the HIRMAb–IDS fusion protein, there is high BBB penetration in the mouse of an IDS fusion protein and a chimeric MAb against the mouse TfR. The comparison of the brain distribution of two different IgG-IDS fusion proteins, with different reactivity for an endogenous BBB receptor, illustrates the difference in brain targeting of a biopharmaceutical caused by the targeting properties of the IgG domain of the fusion protein.     

利巴韦林不同给药途径治疗婴幼儿上呼吸道感染的临床观察

目的：评价利巴韦林三种给药途径治疗急性上呼吸道感染的临床疗效。方法：255例婴幼儿急性上呼吸道感染随机分为利巴韦林肌肉注射组、静脉给药组、滴鼻给药组,在综合治疗基础上加用利巴韦林,分别给予肌肉注射、静脉给药、鼻腔给药。结果：肌注显效率52.7％,总有效率77．7％;静脉给药显效率58.13％,总有效率90．2％;滴鼻显效率59．5％。总有效率91．0％。结论：利巴韦林滴鼻安全、有效、经济,因此在使用利巴林治疗病毒性急性上呼吸道感染时首选鼻腔滴入。