Indirect Evidence that Drug Brain Targeting Using Polysorbate 80-Coated Polybutylcyanoacrylate Nanoparticles Is Related to Toxicity

Purpose. To investigate the mechanism underlying the entry of the analgesic peptide dalargin into brain using biodegradable polybutylcyanoacrylate (PBCA) nanoparticles (NP) overcoated with polysorbate 80. Methods. The investigations were carried out with PBCA NP and with non biodegradable polystyrene (PS) NP (200 nm diameter). Dalargin adsorption was assessed by HPLC. Its entry into the CNS in mice was evaluated using the tail-flick procedure. Locomotor activity measurements were performed to compare NP toxicities. BBB permeabilization by PBCA NP was studied in vitro using a coculture of bovine brain capillary endothelial cells and rat astrocytes. Results. Dalargin loading was 11.7 µg/mg on PBCA NP and 16.5µg/ mg on PS NP. Adding polysorbate 80 to NP led to a complete desorption. Nevertheless, dalargin associated with PBCA NP and polysorbate 80 induced a potent and prolonged analgesia, which could not be obtained using PS NP in place of PBCA NP. Locomotor activity dramatically decreased in mice dosed with PBCA NP, but not with PS NP. PBCA NP also caused occasional mortality. In vitro, PBCA NP (10 µg/ml) induced a permeabilization of the BBB model. Conclusions. A non specific permeabilization of the BBB, probably related to the toxicity of the carrier, may account for the CNS penetration of dalargin associated with PBCA NP and polysorbate 80.     

Delivery of Loperamide Across the Blood-Brain Barrier with Polysorbate 80-Coated Polybutylcyanoacrylate Nanoparticles

Purpose. The possibility of using polysorbate 80-coated nanoparticles for the delivery of the water insoluble opioid agonist loperamide across the blood-brain barrier was investigated. The analgesic effect after i.v. injection of the preparations was used to indicate drug transport through this barrier. Methods. Loperamide was incorporated into PBCA nanoparticles. Drug-containing nanoparticles were coated with polysorbate 80 and injected intravenously into mice. Analgesia was then measured by the tail-flick test. Results. Intravenous injection of the particulate formulation resulted in a long and significant analgesic effect. A polysorbate 80 loperamide solution induced a much less pronounced and very short analgesia. Uncoated nanoparticles loaded with loperamide were unable to produce analgesia. Conclusions. Polysorbate 80-coated PBCA nanoparticles loaded with loperamide enabled the transport of loperamide to the brain.     

Long-Circulating PEGylated Polycyanoacrylate Nanoparticles as New Drug Carrier for Brain Delivery

Purpose. The aim of this study was to evaluate the ability of long-circulating PEGylated cyanoacrylate nanoparticles to diffuse into the brain tissue. Methods. Biodistribution profiles and brain concentrations of [¹⁴C]-radiolabeled PEG-PHDCA, polysorbate 80 or poloxamine 908-coated PHDCA nanoparticles, and uncoated PHDCA nanoparticles were determined by radioactivity counting after intravenous administration in mice and rats. In addition, the integrity of the blood-brain barrier (BBB) after nanoparticles administration was evaluated by in vivo quantification of the diffusion of [¹⁴C]-sucrose into the brain. The location of fluorescent nanoparticles in the brain was also investigated by epi-fluorescent microscopy. Results. Based on their long-circulating characteristics, PEGylated PHDCA nanoparticles penetrated into the brain to a larger extent than all the other tested formulations. Particles were localized in the ependymal cells of the choroid plexuses, in the epithelial cells of pia mater and ventricles, and to a lower extent in the capillary endothelial cells of BBB. These phenomena occurred without any modification of BBB permeability whereas polysorbate 80-coated nanoparticles owed, in part, their efficacy to BBB permeabilization induced by the surfactant. Poloxamine 908-coated nanoparticles failed to increase brain concentration probably because of their inability to interact with cells. Conclusions. This study proposes PEGylated poly (cyanoacrylate) nanoparticles as a new brain delivery system and highlights two requirements to design adequate delivery systems for such a purpose: a) long-circulating properties of the carrier, and b) appropriate surface characteristics to allow interactions with BBB endothelial cells.     

Polysorbate-stabilized solid lipid nanoparticles as colloidal carriers for intravenous targeting of drugs to the brain: Comparison of plasma protein adsorption patterns

Plasma proteins enriched on the surface of drug-delivery-purpose nanoparticles are regarded as key factors for determination of in vivo organ distribution after intravenous injection. Polysorbate 80-coated polybutylcyanoacrylate (PBCA) nanoparticles, preferentially adsorbing apolipoprotein E (apoE) on their surface, have previously been considered to deliver various drugs to the brain. In the present study, in vivo well tolerable solid lipid nanoparticles (SLN) using different types of polysorbates as stabilizers were produced. The influence of the different surfactants on in vitro adsorption of human plasma proteins was investigated using two-dimensional polyacrylamide gel electrophoresis (2-DE). Possible correlations of different amounts of adsorbed apoE to the hydrophilic–lipophilic balance (HLB) of the polysorbates are shown and discussed. Apolipoprotein C-II, albumin and immunoglobulin G, which are also decisive plasma proteins with regard to site-specific drug delivery of intravenously injected carriers to the brain, are compared with regard to adsorption. Moreover, certain similarities to the plasma protein adsorption patterns of previously analysed brain-specific PBCA nanoparticles could be detected. Despite some differences in adsorption behavior of proteins on the surface of polysorbate-stabilized SLN and PBCA nanoparticles, we conclude that in both cases polysorbate 80 might have the highest potential to deliver drugs to the brain.     

In Vivo and in Vitro Assessment of Baseline Blood-Brain Barrier Parameters in the Presence of Novel Nanoparticles

Purpose. Nanoparticles have advantage as CNS drug delivery vehicles given they disguise drug permeation limiting characteristics. Conflicting toxicological data, however, is published with regard to blood-brain barrier integrity and gross mortality. Methods. To address this issue two novel nanoparticle types: emulsifying wax/Brij 78and Brij 72/Tween 80 nanoparticles were evaluated in vivo for effect on cerebral perfusion flow, barrier integrity, and permeability using the in situ brain perfusion technique. Additional evaluation was completed in vitro using bovine brain microvessel endothelial cells for effect on integrity, permeability, cationic transport interactions, and tight junction protein expression. Results. In the presence of either nanoparticle formulation, no overall significant differences were observed for cerebral perfusion flow in vivo. Furthermore, observed in vitro and in vivo data showed no statistical changes in barrier integrity, membrane permeability, or facilitated choline transport. Western blot analyses of occludin and claudin-1 confirmed no protein expression changes with incubation of either nanoparticle. Conclusions. The nanoparticle formulations appear to have no effect on primary BBB parameters in established in vitro and in vivo blood-brain barrier models.     

Apolipoprotein-mediated transport of nanoparticle-bound drugs across the blood-brain barrier

Recent studies have shown that drugs that are normally unable to cross the blood-brain barrier (BBB) following intravenous injection can be transported across this barrier by binding to poly(butyl cyanoacrylate) nanoparticles and coating with polysorbate 80. However, the mechanism of this transport so far was not known. In the present paper, the possible involvement of apolipoproteins in the transport of nanoparticle-bound drugs into the brain is investigated. Poly(butyl cyanoacrylate) nanoparticles loaded with the hexapeptide dalargin were coated with the apolipoproteins AII, B, CII, E, or J without or after precoating with polysorbate 80. In addition, loperamide-loaded nanoparticles were coated with apolipoprotein E alone or again after precoating with polysorbate 80. After intravenous injection to ICR mice the antinociceptive threshold was measured by the tail flick test. Furthermore, the antinociceptive threshold of polysorbate 80-coated dalargin-loaded nanoparticles was determined in ApoEtm1Unc and C57BL/6J mice. The results show that only dalargin or loperamide-loaded nanoparticles coated with polysorbate 80 and/or with apolipoprotein B or E were able to achieve an antinociceptive effect. This effect was significantly higher after polysorbate-precoating and apolipoprotein B or E-overcoating. With the apolipoprotein E-deficient ApoEtm1Unc mice the antinociceptive effect was considerably reduced in comparison to the C57BL/6J mice. These results suggest that apolipoproteins B and E are involved in the mediation of the transport of drugs bound to poly(butyl cyanoacrylate) nanoparticles across the BBB. Polysorbate 80-coated nanoparticles adsorb these apolipoproteins from the blood after injection and thus seem to mimic lipoprotein particles that could be taken up by the brain capillary endothelial cells via receptor-mediated endocytosis. Bound drugs then may be further transported into the brain by diffusion following release within the endothelial cells or, alternatively, by transcytosis.     

Cytotoxicity and apoptotic gene expression in an in vitro model of the blood–brain barrier following exposure to poly(butylcyanoacrylate) nanoparticles

Background Poly(butylcyanoacrylate) (PBCA) nanoparticles (NPs) loaded with doxorubicin (DOX) and coated with polysorbate 80 (PS80) have shown efficacy in the treatment of rat glioblastoma. However, cytotoxicity of this treatment remains unclear.

Purpose The purpose of this study was to investigate cytotoxicity and apoptotic gene expression using a proven in vitro co-culture model of the blood–brain barrier.

Methods The co-cultures were exposed to uncoated PBCA NPs, PBCA-PS80 NPs or PBCA-PS80-DOX NPs at varying concentrations and evaluated using a resazurin-based cytotoxicity assay and an 84-gene apoptosis RT-PCR array.

Results The cytotoxicity assays showed PBCA-PS80-DOX NPs exhibited a decrease in metabolic function at lower concentrations than uncoated PBCA NPs and PBCA-PS80 NPs. The apoptosis arrays showed differential expression of 18 genes in PBCA-PS80-DOX treated cells compared to the untreated control.

Discussion As expected, the cytotoxicity assays demonstrated enhanced dose-dependent toxicity in the DOX loaded NPs. The differentially expressed apoptotic genes participate in both the tumor necrosis factor receptor-1 and mitochondria-associated apoptotic pathways implicated in current DOX chemotherapeutic toxicity.

Conclusion The following data suggest that the cytotoxic effect may be attributed to DOX and not the NPs themselves, further supporting the use of PBCA-PS80 NPs as an effective drug delivery vehicle for treating central nervous system conditions.     

Major effects on blood-retina barrier passage by minor alterations in design of polybutylcyanoacrylate nanoparticles

Abstract

Because the blood-brain barrier (BBB) is an obstacle for drug-delivery, carrier systems such as polybutylcyanoacrylate (PBCA) nanoparticles (NPs) have been studied. Yet, little is known of how physiochemical features such as size, surfactants and surface charge influence BBB passage in vivo. We now used a rat model of in vivo imaging of the retina - which is brain tissue and can reflect the situation at the BBB - to study how size and surface charge determine NPs’ ability to cross the blood-retina barrier (BRB). Interestingly, for poloxamer 188-modified, DEAE-dextran-stabilised, fluorescent PBCA NPs, decreasing the average zeta-size from 272?nm to 172?nm by centrifugation reduced the BRB passage of the NPs substantially. Varying the zeta potential within the narrow range of 0–15?mV by adding different amounts of stabiliser revealed that 0?mV and 15?mV were less desirable than 5?mV which facilitated the BRB passage. Moreover, whether the fluorescent marker was adsorbed or incorporated also influenced the transport into the retina tissue. Thus, minor changes in design of nano-carriers can alter physicochemical parameters such as size or zeta potential, thus substantially influencing NPs’ biological distribution in vivo, possibly by interactions with blood constituents and peripheral organs.     

Apolipoprotein-mediated Transport of Nanoparticle-bound Drugs Across the Blood-Brain Barrier

Recent studies have shown that drugs that are normally unable to cross the blood-brain barrier (BBB) following intravenous injection can be transported across this barrier by binding to poly(butyl cyanoacrylate) nanoparticles and coating with polysorbate 80. However, the mechanism of this transport so far was not known. In the present paper, the possible involvement of apolipoproteins in the transport of nanoparticle-bound drugs into the brain is investigated. Poly(butyl cyanoacrylate) nanoparticles loaded with the hexapeptide dalargin were coated with the apolipoproteins AII, B, CII, E, or J without or after precoating with polysorbate 80. In addition, loperamide-loaded nanoparticles were coated with apolipoprotein E alone or again after precoating with polysorbate 80. After intravenous injection to ICR mice the antinociceptive threshold was measured by the tail flick test. Furthermore, the antinociceptive threshold of polysorbate 80-coated dalargin-loaded nanoparticles was determined in ApoEtm1Unc and C57BL/6J mice. The results show that only dalargin or loperamide-loaded nanoparticles coated with polysorbate 80 and/or with apolipoprotein B or E were able to achieve an antinociceptive effect. This effect was significantly higher after polysorbate-precoating and apolipoprotein B or E-overcoating. With the apolipoprotein E-deficient ApoEtm1Unc mice the antinociceptive effect was considerably reduced in comparison to the C57BL/6J mice. These results suggest that apolipoproteins B and E are involved in the mediation of the transport of drugs bound to poly(butyl cyanoacrylate) nanoparticles across the BBB. Polysorbate 80-coated nanoparticles adsorb these apolipoproteins from the blood after injection and thus seem to mimic lipoprotein particles that could be taken up by the brain capillary endothelial cells via receptor-mediated endocytosis. Bound drugs then may be further transported into the brain by diffusion following release within the endothelial cells or, alternatively, by transcytosis.     

A Comparative Study of Orally Delivered PBCA and ApoE Coupled BSA Nanoparticles for Brain Targeting of Sumatriptan Succinate in Therapeutic Management of Migraine

Purpose

The present investigation aimed at brain targeting of sumatriptan succinate (SS) for its optimal therapeutic effect in migraine through nanoparticulate drug delivery system using poly (butyl cyanoacrylate) (PBCA) and bovine serum albumin linked with apolipoprotein E3 (BSA-ApoE).

Method

The study involved formulation optimization of PBCA nanoparticles (NPs) using central composite design for achieving minimum particle size, maximum entrapment efficiency along with sustained drug release. SS incorporated in BSA-ApoE NPs (S-AA-NP) were prepared by desolvation technique and compared with SS loaded polysorbate 80 coated optimized PBCA NPs (FP_opt) in terms of their brain uptake potential, upon oral administration in male Wistar rats. The NPs were characterized by FTIR, thermal, powder XRD and TEM analysis.

Results

The in vivo studies of FP_opt and S-AA-NP on male Wistar rats demonstrated a fairly high brain/plasma drug ratio of 9.45 and 12.67 respectively 2 h post oral drug administration. The behavioural studies on male Swiss albino mice affirmed the enhanced anti-migraine potential of S-AA-NP than FP_opt (P?<?0.001).

Conclusion

The results of this work, therefore, indicate that BSA-ApoE NPs are significantly better than polysorbate 80 coated PBCA NPs for brain targeting of SS (P?<?0.05) and also offer an improved therapeutic strategy for migraine management.

     

Surface-coated PLA nanoparticles loaded with temozolomide for improved brain deposition and potential treatment of gliomas: development,characterization and in vivo studies

Hydrophobicity of PLA nanoparticles makes them a good substrate for macrophageal and reticulo-endothelial system uptake. Long-circulating properties can be imparted to these particles by coating them with hydrophilic stabilizers. Surface-modified PLA nanoparticles loaded with anti-cancer agent temozolomide were fabricated by solvent evaporation method and coated with surface modifiers. Selection of the surface modifier was based upon uptake of nanoparticles by K9 cells (liver cells). The particles were prepared and characterized for various physicochemical properties using transmission electron microscopy, differential scanning calorimetry, powder X-ray diffraction and in vitro dissolution studies. In vitro BBB permeation studies were performed using the co-culture model developed by using Madin–Darby canine kidney and C6 glioma cells as endothelial and glial cells, respectively. In vitro C6 glioma cell cytotoxicity, cellular proliferation, cellular migration and cellular uptake studies due to developed nanoparticles was assessed. In vivo studies such as pharmacokinetics, qualitative and quantitative biodistribution studies were performed for the developed nanoparticles. Drug-loaded nanoparticles with entrapment efficiency of 50% were developed. PEG-1000 and polysorbate-80 coated nanoparticles were least taken up by the liver cells. Characterization of the nanoparticles revealed formation of spherical shape nanoparticles, with no drug and excipient interaction. In vivo pharmacokinetics of developed nanoparticles depicted enhancement of half-life, area under the curve and mean residence time of the drug. Qualitative and quantitative biodistribution studies confirmed enhanced permeation of the drug into the brain upon loading into nanoparticles with less deposition in the highly perfused organs like lung, liver, spleen, heart and kidney.     

Brain Delivery of NAP with PEG-PLGA Nanoparticles Modified with Phage Display Peptides

Purpose

A phage-displayed peptide TGN was used as a targeting motif to help the delivery of NAP-loaded nanoparticles across the blood–brain barrier (BBB), which sets an obstacle for brain delivery of NAP in vivo.

Methods

Intracerebroventricular injection of Aβ_1-40 into mice was used to construct in vivo model of Alzheimer’s disease. The water maze task was performed to evaluate the effects of the NAP formulations on learning and memory deficits in mice. The neuroprotective effect was tested by detecting acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) activity and conducting histological assays.

Results

Intravenous administration of NAP-loaded TGN modified nanoparticles (TGN-NP/NAP) has shown better improvement in spatial learning than NAP solution and NAP-loaded nanoparticles in Morris water maze experiment. The crossing number of the mice with memory deficits recovered after treatment with TGN-NP/NAP in a dose dependent manner. Similar results were also observed in AChE and ChAT activity. No morphological damage and no detectable Aβ plaques were found in mice hippocampus and cortex treated with TGN-NP/NAP.

Conclusions

TGN modified nanoparticles could be a promising drug delivery system for peptide and protein drug such as NAP to enter the brain and play the therapeutic role.     

Double-coated poly (butylcynanoacrylate) nanoparticulate delivery systems for brain targeting of dalargin via oral administration

The aim of this study is to evaluate oral administration of poly (butylcyanoacrylate) nanoparticulate delivery systems (PBCA-NDSs), double-coated with Tween 80 and poly (ethylene) glycol (PEG) 20000 for brain delivery of hexapeptide dalargin, an anti-nociceptive peptide that does not cross blood-brain barrier (BBB) by itself. Studies have proven the brain uptake of Tween 80 overcoated nanoparticles after intravenous administration, but studies for brain delivery of nanoparticles after oral administration had been limited due to reduced bioavailability of nanoparticles and extensive degradation of the peptide and/or nanoparticles by gastrointestinal enzymes. To address this problem, dalargin-loaded PBCA-NDS were successively double-coated with Tween 80 and PEG 20000 in varied concentrations of up to 2% each. Measurement of in vivo central anti-nociceptive effect of dalargin along with a dose response curve was obtained by the tail flick test following the oral administration of PBCA-NDSs to mice. Results from the tail flick test indicated that significant dalargin-induced analgesia was observed from PBCA-NDSs with double-coating of Tween and PEG in comparison with single-coating of either Tween or PEG. Hence, it could be concluded that surface coated PBCA-NDS can be used successfully for brain targeting of dalargin or other peptides administered orally. However, further studies are required to elucidate the exact transport mechanism of PBCA-NDSs from gastrointestinal tract to brain.     

Interaction Between Polyalkylcyanoacrylate Nanoparticles and Peritoneal Macrophages: MTT Metabolism,NET Reduction,and NO Production

Purpose. The nature of interactions between macrophages and drug carriers is of primordial importance either in the design of more effective therapeutic strategies for macrophage-associated pathogenesis or in establishing new approaches for pharmacological action avoiding macrophages. Methods. Polyalkylcyanoacrylate nanoparticles (PMCA, PECA, PBCA and PIBCA nanoparticles) were assayed for their toxicity on peritoneal resident and thioglycolate-elicited macrophages. Cellular viability was assessed by MTT tetrazolium salt assay, oxidative burst by NBT reduction and NO production by nitrite evaluation. Results. The nanoparticles tested led to cellular morphological modifications and induced toxicity in both types of macrophages in culture. The polyalkylcyanoacrylate nanoparticles uptake by peritoneal macrophages caused an increase in respiratory burst, as assessed by the NBT reduction assay, and induced the release of soluble toxic factors to the culture medium. The association of LPS with the PMCA nanoparticles significantly stimulated the production of nitric oxide (NO) by resident macrophages. In contrast, the association of PBCA nanoparticles with LPS does not increase the nitrite production as compared with LPS alone, which may be due to a different physico-chemical interaction between LPS and the two types of polymers. Conclusions. In cultured mice peritoneal macrophages, nanoparticles of PACA induce the production of oxygen reactive products, which cause changes in the cell metabolism of both resident and elicited macrophages. PMCA nanoparticles in association with LPS significantly increase the expression of the inducible isoform of nitric oxide synthase, leading to the release of large amount of NO, which may be highly cytotoxic to the cultured cells in the presence of peroxide generated from the oxidative burst.     

载吉西他滨介孔二氧化硅纳米粒的制备及其抗肿瘤活性评价

目的：制备载吉西他滨(gemcitabine,GemC)的介孔二氧化硅纳米粒(MSN),并对其体内外抗肿瘤活性进行评价。方法：采用聚合法制备了GemC-MSN,采用激光粒度仪测定了纳米粒的粒度分布和电位,并通过透射电镜对纳米粒的形态进行了表征。应用紫外可见分光光度法评价了纳米粒的载药量、包封率及体外释放特性。采用MTT染色法,考察了GemC-MSN对A549细胞的体外细胞毒性。建立了体内肿瘤动物模型,评价纳米粒的体内抗肿瘤活性。结果：纳米粒分布均一,平均粒径为107.29 nm,PDI为0. 167,Zeta电位为0.107mV;药物的载药量和包封率分别为(37.31±1.25)%和(87.37±2.12)%;体外释放结果显示,纳米粒具有一定的缓释作用,96h时释放达到平衡;体内外抗肿瘤试验结果表明,GemC-MSN较游离GemC具有更强的抗肿瘤活性。结论：MSN作为药物的新型载体,具有良好的生物相容性,并能显著提高GemC的载药量,控制药物的缓慢释放,能显著提高GemC的体内外抗肿瘤活性,将为GemC新型给药系统的深入研究提供参考。     

Drug delivery to the brain with nanoparticles

Drugs can be delivered to brain with the aid of poly(butylcyanoacrylate) (PBCA) nanoparticles coated with polysorbate 80. These carriers can penetrate BBB and deliver drugs of various structures, including peptides, hydrophilic compounds, and lipophilic compounds eliminated from brain with P-glycoprotein. When a suspension of polysorbate-coated PBCA nanoparticles is introduced into blood, apolipoproteins of the blood plasma adsorb on the particle surface and then interact with receptors of low-density lipoproteins situated in endothelial cells of cerebral vessels, thus stimulating endocytosis.     

Up-regulating Blood Brain Barrier Permeability of Nanoparticles via Multivalent Effect

Purpose

To investigate the multivalent effect for up-regulating the intracerebral delivery of nanoparticles via receptor-mediated transcytosis.

Methods

Nanoparticles labeled with near-infrared (NIR) fluorophore and different numbers of angiopep-2 peptides that specifically target low-density lipoprotein receptor-related protein (LRP) on the brain capillary endothelial cells were developed. Bio-distribution studies quantified the intracerebral uptakes of these nanoparticles at 2 and 24 h after intravenous injection. In vivo NIR fluorescence imaging, ex vivo autoradiographic imaging and 3D reconstructed NIR fluorescence imaging revealed the nanoparticle distribution pattern in brain. Fluorescence microscopic imaging identified the nanoparticle locations at the cellular level.

Results

The multimetirc association between the angiopep-2 peptides labeled on the nanoparticle and the LRP receptors on the brain capillary endothelial cells significantly increased the intracerebral uptake of the nanoparticles. Nanoparticle Den-Angio4 labeled four angiopep-2 peptides achieved the highest BBB traverse efficacy. After penetrating the BBB, Den-Angio4 distributed heterogeneously and mainly located at hippocampus, striatum and cerebellum in the brains.

Conclusions

The multivalent effect significantly enhances the BBB permeability of nanoparticles. Den-Angio4 as a nanoparticle prototype provides a two order targeted strategy for diagnosis or treatment of central nerver system diseases by first traversing the BBB via receptor-mediated endocytosis and secondly targeting the leisions with high receptor expression level.     

Brain-targeted delivery of doxorubicin using glutathione-coated nanoparticles for brain cancers

Abstract

Objectives: To prepare and characterize in vitro a novel brain-targeted delivery of doxorubicin using glutathione-coated nanoparticles (NPs) for the treatment of brain cancer.

Methods: Doxorubicin-loaded NPs were prepared by the nanoprecipitation method using PLGA-COOH (dl-lactide-co-glycolide). The NPs were coated with a glutathione-PEG conjugate (PEG-GSH) in order to target delivery to the brain. The NPs were characterized via in vitro studies to determine particle size, drug release, cellular uptake, immunofluorescence study, cytotoxic assay, and in vitro blood–brain barrier (BBB) assay.

Results: The NPs showed a particle size suitable for BBB permeation (particle size around 200?nm). The in vitro release profile of the NPs exhibited no initial burst release and showed sustained drug release for up to 96?h. The immunofluorescence study showed the glutathione coating does not interfere with the drug release. Furthermore, in vitro BBB Transwell? study showed significantly higher permeation of the doxorubicin-loaded NPs compared with the free doxorubicin solution through the coculture of rat brain endothelial (RBE4) and C6 astrocytoma cells (p?<?0.05).

Conclusions: We conclude that the initial in vitro characterization of the NPs demonstrates potential in delivering doxorubicin to cancer cells with possible future application in targeting brain cancers in vivo.     

Solid lipid nanoparticles as a drug delivery system for the treatment of neurodegenerative diseases

ABSTRACT

Introduction: The failure of many molecules as CNS bioactive compounds is due to many restrictions: poor water solubility, intestinal absorption, in vivo stability, bioavailability, therapeutic effectiveness, side effects, plasma fluctuations, and difficulty crossing physiological barriers, like the brain blood barrier (BBB), to deliver the drug directly to the site of action.

Area covered: Nanotechnology-based approaches with the employment of liposomes, micelles, dendrimers, and solid lipid nanoparticles (SLN) as drug delivery systems, are used to overcome the above reported limitations. Here, we focus on the delivery of drugs based on SLN formulation to treat neurodegenerative diseases. Notably, SLN have the ability to protect drugs from chemical and enzymatic degradation, direct the active compound towards the target site with a substantial reduction of toxicity for the adjacent tissues, and pass physiological barriers increasing bioavailability without resorting to high dosage forms.

Expert opinion: We believe that SLN could represent a suitable tool to pass the BBB and permit drugs to reach damaged areas of the CNS in patients affected by neurodegenerative pathologies, such as Alzheimer’s and Parkinson’s diseases.     

Pharmacokinetic-Pharmacodynamic Modelling of Morphine Transport Across the Blood-Brain Barrier as a Cause of the Antinociceptive Effect Delay in Rats—A Microdialysis Study

Purpose. To quantify the contribution of distributional processes across the blood-brain barrier (BBB) to the delay in antinociceptive effect of morphine in rats. Methods. Unbound morphine concentrations were monitored in venous blood and in brain extracellular fluid (ECF) using microdialysis (MD) and in arterial blood by regular sampling. Retrodialysis by drug was used for in vivo calibration of the MD probes. Morphine was infused (10 or 40 mg/kg) over 10 min intravenously. Nociception, measured by the electrical stimulation vocalisation method, and blood gas status were determined. Results. The half-life of unbound morphine in striatum was 44 min compared to 30 min in venous and arterial blood (p < 0.05). The BBB equilibration of morphine, expressed as the ratio of areas under the curve between striatum and venous blood, was less than unity (0.28 ± 0.09 and 0.22 ± 0.17 for 10 and 40 mg/kg), respectively, indicating active efflux of morphine across the BBB. The concentration-effect relationship exhibited a clear hysterisis with an effect delay half-life of 32 and 5 min based on arterial blood and brain ECF concentrations, respectively. Conclusions. Eighty five percent of the effect delay was caused by morphine transport across the BBB, indicating possible involvement of rate limiting mechanisms at the receptor level or distributional phenomena for the remaining effect delay of 5 min.