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Progress in treating central nervous system (CNS) disorders is retarded owing to a limited understanding of brain disease pathology. Additionally, the blood–brain barrier (BBB) limits molecular entry into the brain. Many approaches for brain drug delivery to overcome the BBB, such as BBB permeability enhancement, transient BBB disruption, and direct surgical administration have been explored with limited success. Recent research has shown that direct vascular channels exist between the skull bone marrow and the meninges, allowing myeloid and lymphoid cells to migrate. We hypothesized that these direct channels may also allow brain drug delivery from the skull bone marrow to the brain. In this study, for the first time we propose intraosseous administration of drugs into the skull (intracalvariosseous [ICO]) as a novel approach for brain drug delivery via BBB bypassing routes. We tested the feasibility of the approach by applying nine representative compounds over thinned mouse skulls to simulate ICO and measuring the compound entry level in the brain compared to that after systemic administration. Surprisingly, we found that the skull is not completely impermeable to drug penetration into the brain and the tested compounds reached the brain tissue several tens‐to‐hundred times higher by ICO than systemic application. These findings suggest a role for the BBB bypassing route from skull to brain, apart from the systemic route, in the drug entry into the brain after ICO. This approach should be applicable to other CNS drugs and even BBB impermeable drugs. Overall ICO provides an innovative and advantageous pathway for effective treatment of brain diseases. [ABSTRACT FROM AUTHOR]

In a rat model, following exposure to rat folate receptor alpha antibodies (FRαAb) during gestation, FRαAb accumulates in the placenta and the fetus and blocks folate transport to the fetal brain and produces behavioral deficits in the offspring. These deficits could be prevented with folinic acid. Therefore, we sought to evaluate folate transport to the brain in young rat pups and determine what effect FRαAb has on this process, to better understand the folate receptor autoimmune disorder associated with cerebral folate deficiency (CFD) in autism spectrum disorders (ASD). When injected intraperitoneally (IP), FRαAb localizes to the choroid plexus and blood vessels including the capillaries throughout the brain parenchyma. Biotin-tagged folic acid shows distribution in the white matter tracts in the cerebrum and cerebellum. Since these antibodies can block folate transport to the brain, we orally administered various folate forms to identify the form that is better-absorbed and transported to the brain and is most effective in restoring cerebral folate status in the presence of FRαAb. The three forms of folate, namely folic acid, D,L-folinic acid and levofolinate, are converted to methylfolate while L-methylfolate is absorbed as such and all are efficiently distributed to the brain. However, significantly higher folate concentration is seen in the cerebrum and cerebellum with levofolinate in the presence or absence of FRαAb. Our results in the rat model support testing levofolinate to treat CFD in children with ASD. [ABSTRACT FROM AUTHOR]

Abstract Progress in treating central nervous system (CNS) disorders is retarded owing to a limited understanding of brain disease pathology. Additionally, the blood–brain barrier (BBB) limits molecular entry into the brain. Many approaches for brain drug delivery to overcome the BBB, such as BBB permeability enhancement, transient BBB disruption, and direct surgical administration have been explored with limited success. Recent research has shown that direct vascular channels exist between the skull bone marrow and the meninges, allowing myeloid and lymphoid cells to migrate. We hypothesized that these direct channels may also allow brain drug delivery from the skull bone marrow to the brain. In this study, for the first time we propose intraosseous administration of drugs into the skull (intracalvariosseous [ICO]) as a novel approach for brain drug delivery via BBB bypassing routes. We tested the feasibility of the approach by applying nine representative compounds over thinned mouse skulls to simulate ICO and measuring the compound entry level in the brain compared to that after systemic administration. Surprisingly, we found that the skull is not completely impermeable to drug penetration into the brain and the tested compounds reached the brain tissue several tens‐to‐hundred times higher by ICO than systemic application. These findings suggest a role for the BBB bypassing route from skull to brain, apart from the systemic route, in the drug entry into the brain after ICO. This approach should be applicable to other CNS drugs and even BBB impermeable drugs. Overall ICO provides an innovative and advantageous pathway for effective treatment of brain diseases.

Piperine (PIP) is a neuroprotective phytomedicine that has profound acetylcholine esterase and reactive oxygen species inhibition effect in Alzheimer's disease (AD) model. However, the oral delivery of PIP is limited by poor aqueous solubility and low bioavailability in systemic circulation. To improve the PIP bioavailability, the polyamidoamine (PAMAM) G4 dendrimer is grafted with tocopheryl polyethylene glycol succinate-1000 (TPGS) through carbodiimide chemistry to form TPGS-PAMAM conjugate. The TPGS-PAMAM coupling was confirmed through proton NMR and FTIR techniques. PIP was encapsulated in the TPGS-PAMAM through solvent diffusion method to form PIP-TPGS-PAMAM. The particle size for PIP-TPGS-PAMAM found the less than 50 nm, whereas entrapment efficiency found to 87 ± 3.5% and 10.6 ± 2.9% drug loading. The powder differential scanning calorimetry and powder X-ray diffraction characterization were employed to evaluate the amorphous encapsulation of the PIP in TPGS-PAMAM. The PIP-TPGS-PAMAM stability was studied in the gastric fluids which showed no drastic difference in particle size and encapsulation efficiency compared to PIP-PAMAM. The in vitro release analysis revealed 37 ± 4.1% PIP release from the PIP-TPGS-PAMAM matrix, and 71 ± 4.9% PIP release from the PIP-PAMAM dendrimer was observed in 48 h. The single-dose oral gavage to Wistar rats of PIP-TPGS-PAMAM showed the AUC0-∞ 14.38 µg/mL.h, Cmax 7.77 ± 1.65 µg/mL, Tmax, 1.6 ± 0.18 h, and half-life 3.47 ± 0.64 h for PIP in systemic circulation. PIP-PAMAM and free PIP showed significantly poor AUC0-∞ compared to PIP-TPGS-PAMAM. The brain uptake studies revealed PIP-TPGS-PAMAM treated group showed 2.2 ± 0.37 µg/g PIP content compared to free PIP administered group which was 0.4 ± 0.10 µg/g. Therefore, PIP-TPGS-PAMAM can offer excellent prospect for the delivery hydrophobic drugs to brain in AD. [ABSTRACT FROM AUTHOR]

Monoclonal antibodies play an important role in the treatment of various diseases. However, the development of these drugs against neurological disorders where the drug target is located in the brain is challenging and requires a good understanding of the local drug concentration in the brain. In this original research, we investigated the systemic and local pharmacokinetics in the brain of healthy rats after either intravenous (IV) or intracerebroventricular (ICV) administration of EGFRvIII-T-Cell bispecific (TCB), a bispecific monoclonal antibody. We established an experimental protocol that allows serial sampling in serum, cerebrospinal fluid (CSF) and interstitial fluid (ISF) of the prefrontal cortex in freely moving rats. For detection of drug concentration in ISF, a push-pull microdialysis technique with large pore membranes was applied. Brain uptake into CSF and ISF was characterized and quantified with a reduced brain physiologically-based pharmacokinetic model. The model allowed us to interpret the pharmacokinetic processes of brain uptake after different routes of administration. The proposed model capturing the pharmacokinetics in serum, CSF and ISF of the prefrontal cortex suggests a barrier function between the CSF and ISF that impedes free antibody transfer. This finding suggests that ICV administration may not be better suited to reach higher local drug exposure as compared to IV administration. The model enabled us to quantify the relative contribution of the blood-brain barrier (BBB) and Blood-CSF-Barrier to the uptake into the interstitial fluid of the brain. In addition, we compared the brain uptake of three monoclonal antibodies after IV dosing. In summary, the presented approach can be applied to profile compounds based on their relative uptake in the brain and provides quantitative insights into which pathways are contributing to the net exposure in the brain. [ABSTRACT FROM AUTHOR]

Monoclonal antibodies play an important role in the treatment of various diseases. However, the development of these drugs against neurological disorders where the drug target is located in the brain is challenging and requires a good understanding of the local drug concentration in the brain. In this original research, we investigated the systemic and local pharmacokinetics in the brain of healthy rats after either intravenous (IV) or intracerebroventricular (ICV) administration of EGFRvIII-T-Cell bispecific (TCB), a bispecific monoclonal antibody. We established an experimental protocol that allows serial sampling in serum, cerebrospinal fluid (CSF) and interstitial fluid (ISF) of the prefrontal cortex in freely moving rats. For detection of drug concentration in ISF, a push-pull microdialysis technique with large pore membranes was applied. Brain uptake into CSF and ISF was characterized and quantified with a reduced brain physiologically-based pharmacokinetic model. The model allowed us to interpret the pharmacokinetic processes of brain uptake after different routes of administration. The proposed model capturing the pharmacokinetics in serum, CSF and ISF of the prefrontal cortex suggests a barrier function between the CSF and ISF that impedes free antibody transfer. This finding suggests that ICV administration may not be better suited to reach higher local drug exposure as compared to IV administration. The model enabled us to quantify the relative contribution of the blood-brain barrier (BBB) and Blood-CSF-Barrier to the uptake into the interstitial fluid of the brain. In addition, we compared the brain uptake of three monoclonal antibodies after IV dosing. In summary, the presented approach can be applied to profile compounds based on their relative uptake in the brain and provides quantitative insights into which pathways are contributing to the net exposure in the brain.

Validated LC-MS method for the direct quantitative analysis of galantamine (acetylcholinesterase inhibitor) was developed in rat cerebrospinal fluid and brain homogenate besides rat plasma, utilizing structurally close nalbuphine as an internal standard. After a simple protein precipitation step, samples are separated on 2-μm C18 column kept at 40 °C, using isocratic flow of 80% methanol in pH 9.5 ammonium formate buffer, and retention times were about 1.8 and 2.9 min for galantamine and nalbuphine, respectively. Mass detection with electrospray ionization (ESI) and positive polarity was able to detect 0.2 ng mL-1 galantamine using single ion monitoring mode (SIM) at m/z 288 for galantamine and m/z 358 for nalbuphine. The method showed linearity within the range of 0.5 – 300 ng mL-1. The proposed method was validated according to FDA guidelines. Trueness and precision showed acceptable values at all quality control levels, and recoveries were within 85.6 – 114.3% in all matrices at all runs and with relative standard deviations within 0.2 – 12.4%. The method was used to study in vivo brain uptake and pharmacokinetics of galantamine from brain homogenate and plasma samples following the administration of nasal galantamine-bound chitosan nanoparticles compared to oral and nasal galantamine solutions, in scopolamine-induced Alzheimer's disease rat model. [ABSTRACT FROM AUTHOR]

Methyl cellulose (MC) based nasal in situ gels were developed to enhance the brain delivery of piribedil (PBD), an anti-Parkinson's drug. Different grades of MC and several solutes (NaCl, KCl, Na.Citrate, STPP, PEG-6000, sucrose, etc.) were screened to formulate thermo-responsive nasal in situ gelling systems. Formulations were evaluated for their sol-gel transition temperature and time, rheological behaviour, in vitro drug release, mucociliary clearance (MCC), ex vivo nasal toxicity, and in vivo brain availability studies in Wistar rats. Intranasal (i.n.) administration was carried out using a cannula-microtip setup to deliver PBD at the olfactory region of the nose. The concentration and viscosity grade of MC and also the concentration and type of solute used were found to affect the rheological behaviour of the formulations. Among the solutes tested, NaCl was found to be effective for formulating MC in situ gels. The developed in situ gels significantly delayed the MCC of PBD from the site of administration when compared with conventional suspension (p < 0.05). Further, formulations with higher gel strength showed lower in vitro drug release rate and longer intranasal residence (delayed MCC) (p < 0.05). The absolute brain availability (brain AUC0-t) of PBD increased to 35.92% with i.n. delivery when compared to 4.71% with oral administration. Overall, it can be concluded that intranasal delivery of PBD is advantageous when compared to the currently practiced oral therapy. [ABSTRACT FROM AUTHOR]

The combined use of different therapeutic agents in the treatment of neurodegenerative disorders is a promising strategy to halt the disease progression. In this context, we aimed to combine the anti-inflammatory properties of geraniol (GER) with the mitochondrial rescue effects of ursodeoxycholic acid (UDCA) in a newly-synthesized prodrug, GER-UDCA, a potential candidate against Parkinson's disease (PD). GER-UDCA was successfully synthetized and characterized in vitro for its ability to release the active compounds in physiological environments. Because of its very poor solubility, GER-UDCA was entrapped into both lipid (SLNs) and polymeric (NPs) nanoparticles in order to explore nose-to-brain pathway towards brain targeting. Both GER-UDCA nanocarriers displayed size below 200 nm, negative zeta potential and the ability to increase the aqueous dissolution rate of the prodrug. As SLNs exhibited the higher GER-UDCA dissolution rate, this formulation was selected for the in vivo GER-UDCA brain targeting experiments. The nasal administration of GER-UDCA-SLNs (1 mg/kg of GER-UDCA) allowed to detect the prodrug in rat cerebrospinal fluid (concentration range = 1.1 to 4.65 μg/mL, 30–150 min after the administration), but not in the bloodstream, thus suggesting the direct nose to brain delivery of the prodrug. Finally, histopathological evaluation demonstrated that, in contrast to the pure GER, nasal administration of GER-UDCA-SLNs did not damage the structural integrity of the nasal mucosa. In conclusion, the present data suggest that GER-UDCA-SLNs could provide an effective and non-invasive approach to boost the access of GER and UDCA to the brain with low dosages. Unlabelled Image [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Enhanced oral bioavailability of Darunavir. • Decreased dose related side effects. • Lipid nanoemulsion formulation of Darunavir. • Increased brain uptake of Darunavir. Abstract The present work aimed to formulate Darunavir loaded lipid nanoemulsion to increase its oral bioavailability and enhance brain uptake. Various batches of lipid nanoemulsion of Darunavir were prepared by high pressure homogenization using soya bean oil, egg lecithin and Tween 80. The optimized batch DNE-3 had globule size of 109.5 nm, zeta potential of −41.1 mV, entrapment efficiency 93% and creaming volume 98%. The batch remained stable at 4 °C for 1 month with an insignificant change in globule size and zeta potential (P > 0.05). In-vivo pharmacokinetics male wistar rats indicated 223% bioavailability of Darunavir relative to drug suspension. C max of DNE-3 was twofold higher than suspension form. The organ biodistribution study indicated 2.65 fold higher brain uptake for DNE-3 than that for suspension. The higher bioavailability of Darunavir from nanoemulsion could lessen the dose related side effects. Moreover, high organ distribution results in passive uptake of Darunavir to HIV reservoir organs. [ABSTRACT FROM AUTHOR]

Targeting of antimicrobial agents by means of liposomes may be of great value in the treatment of intra or extracellular infections compare to conventional forms of antimicrobial therapy. In the present study Ampicillin loaded non-targeted Polyethylene glycolated liposomes and targeted Glutathione Polyethylene glycollated liposomes of about 132.14 nm size were prepared with 80 % of drug entrapment. Prepared liposomes were evaluated for in vitro, in vivo release profile and brain uptake studies. Results of these studies revealed more absorption of drug than standard Ampicillin solution and non targeted liposomes (Auc0-6h 1858.908 µg h/ml) and 3.5 times increase in brain uptake. Incorporation of polyethylene glycol in the liposomes increased the drug concentration and circulation time in plasma as well as in the extracellular fluid of brain thus improved therapeutic availability of Ampicillin trihydrate.

Objective(s): Improved brain uptake ratio (IBUR), employing 99mTc-ethyl cysteinate dimer (99mTc-ECD), is an automatic non-invasive method for quantitatively measuring regional cerebral blood flow (rCBF). This method was developed by the reconstruction of the theory and linear regression equation, based on rCBF measurement by H215O positron emission tomography. Clarification of differences in rCBF values obtained by Patlak plot (PP) and IBUR method is important for clinical diagnosis during the transition period between these methods. Our purpose in this study was to demonstrate the relationship between rCBF values obtained by IBUR and PP methods and to evaluate the clinical applicability of IBUR method. Methods: The mean CBF (mCBF) and rCBF values in 15 patients were obtained using the IBUR method and compared with PP method values. Results: Overall, mCBF and rCBF values, obtained using these independent techniques, were found to be correlated (r=0.68). The mCBF values obtained by the IBUR method ranged from 18.9 to 44.9 ml/100g/min, whereas those obtained by the PP method ranged from 34.7 to 48.1 ml/100g/min. The rCBF values obtained by the IBUR method ranged from 16.3 to 60.2 ml/100g/min, whereas those obtained by the PP method were within the range of 26.7-58.8 ml/100g/min. Conclusion: The ranges of mCBF and rCBF values, obtained by the IBUR method, were approximately 60% lower than those obtained by the PP method; therefore, this method can be useful for diagnosing lower flow area. Re-analysis of prior PP data, using the IBUR method, could be potentially useful for the clinical follow-up of rCBF.

Graphical abstract Abstract Surface modified fluorescent silica nanoparticle derivatives (Ru@SNPs), namely, glucose (Glu) and glucose-poly (ethylene glycol) methyl ether amine (Glu-PEG) coated SNPs were designed and tested for their ability to penetrate the blood-brain barrier (BBB) in mice brain. The new obtained nanoparticles were characterized by field emission scanning electron microscope (FE-SEM), dynamic light scattering (DLS) and Fourier transform infrared (FTIR-ATR) analysis. The BBB penetration and distribution of tailored SNPs in mice brain were examined using confocal laser scanning microscopy (CLSM), flow cytometer (FACS) and transmission electron microscopy (TEM). The promising results obtained by in vivo experiments, point out that silica nanoparticle derivatives are an efficient permeable delivery vehicle that are able to cross the BBB and reach the brain tissues via specific and non-specific mechanisms. These findings will enrich the knowledge to rationally engineer multifunctional nanoparticles, and bring new insights into BBB permeability. [ABSTRACT FROM AUTHOR]

Lipid microparticles (LMs) uncoated or coated with chitosan and containing the neuroprotective polyphenol resveratrol were developed for its targeting to the brain via nasal administration. The lipid microparticles loaded with resveratrol (LMs-Res) were produced by melt emulsification, using stearic acid as lipid material and phosphatidylcholine as the surfactant. The chitosan coated particles LMs-Res-Ch (1.75% w/v chitosan solution) and LMs-Res-Ch-plus (8.75% w/v chitosan solution) were prepared by adding a chitosan solution to the formed particles. The mean diameter of the particles were 68.5 ± 3.1 μm, 76.3 ± 5.2 μm and 84.5 ± 8.1 μm for LMs-Res, LMs-Res-Ch and LMs-Res-Ch-plus respectively, suitable for nasal delivery. Chitosan coating changed the particle surface charge from a negative zeta potential value (−12.7 ± 2.1 mV) for the uncoated particles to a higher positive values respectively, 24.0 ± 4.7 and 44.6 ± 3.1 mV for the chitosan coated LM-Res-Ch and LM-Res-Ch-plus. Permeation studies across human NCM460 cell monolayers demonstrated that their transepithelial electrical resistance (TEER) values were not modified in the presence of free resveratrol, unloaded LMs, loaded LMs-Res or LMs-Res-Ch. On the other hand, the TEER values decreased from 150 ± 7 to 41 ± 3 Ω cm 2 in the presence of LMs-Res-Ch-plus, which corresponded to a significant increase in the apparent permeability (P app ) of resveratrol from 518 ± 8 × 10 −4  cm/min to 750 ± 98 × 10 −4  cm/min. In vivo studies demonstrated that no resveratrol was detected in the rat cerebrospinal fluid (CSF) after an intravenous infusion of the polyphenol. Conversely, the nasal delivery of resveratrol in a chitosan suspension or encapsulated in uncoated LMs-Res dispersed in water achieved the uptake of resveratrol in the CSF with C max after 60 min of 1.30 ± 0.30 μg/ml and 0.79 ± 0.15 μg/ml, respectively. However, a dramatic increase in the levels of resveratrol reaching the CSF was attained by the administration of an aqueous suspension of LMs-Res-Ch-plus with a C max after 60 min of 9.7 ± 1.9 μg/ml. This marked increase in the CSF bioavailability was achieved without any distribution in the systemic circulation, demonstrating a direct and specific nose to brain delivery. [ABSTRACT FROM AUTHOR]

Pyrethroids, including permethrin and deltamethrin (DLM), are very widely used of insecticides. It was hypothesized that lower plasma binding and increased blood–brain barrier (BBB) penetration of DLM in immature rats contribute to the higher brain concentrations of DLM and more pronounced neurotoxicity reported in this age group. The left brain of anesthetized adult rats was perfused for 2 min via a carotid artery with 1 μM 14 C-DLM in: 2–5% human serum albumin (HSA); plasma from adult and 15- and 21-d-old rats; and plasma from human donors of: birth–1 week, 1–4 weeks, 4 weeks–1 year, 1–3 years and adults. The fraction of DLM bound and brain uptake of DLM did not vary significantly with the HSA concentration nor with the age of rat or human plasma donors. One, 10 and 50 μM 14 C-DLM were perfused into the left-brain of anesthetized adult, 15- and 21-d-old rats. DLM deposition in the brain was linear over this range of concentrations and inversely related to age. The results of this investigation indicate that increased BBB permeability in the youngest rats enhances brain deposition of the insecticide. Plasma protein binding of DLM in immature rats and humans is not sufficiently diminished to impact its brain uptake. [ABSTRACT FROM AUTHOR]

The advent of dissolution dynamic nuclear polarization (DNP) led to the emergence of a new kind of magnetic resonance (MR) measurements providing the opportunity to probe metabolism in vivo in real time. It has been shown that, following the injection of hyperpolarized substrates prepared using dissolution DNP, specific metabolic bioprobes that can be used to differentiate between healthy and pathological tissue in preclinical and clinical studies can be readily detected by MR thanks to the tremendous signal enhancement. The present article aims at reviewing the studies of cerebral function and metabolism based on the use of hyperpolarized MR. The constraints and future opportunities that this technology could offer are discussed. [ABSTRACT FROM AUTHOR]

Objective: Ferulic acid (Fer) displays antioxidant/anti-inflammatory properties useful against neurodegenerative diseases. To increase Fer uptake and its central nervous system residence time, a dimeric prodrug, optimizing the Fer loading on nasally administrable solid lipid microparticles (SLMs), was developed., Methods: The prodrug was synthesized as Fer dimeric conjugate methylated on the carboxylic moiety. Prodrug antioxidant/anti-inflammatory properties and ability to release Fer in physiologic environments were evaluated. Tristearin or stearic acid SLMs were obtained by hot emulsion technique. In vivo pharmacokinetics were quantified by HPLC., Results: The prodrug was able to release Fer in physiologic environments (whole blood and brain homogenates) and induce in vitro antioxidant/anti-inflammatory effects. Its half-life in rats was 18.0 ± 1.9 min. Stearic acid SLMs, exhibiting the highest prodrug loading and dissolution rate, were selected for nasal administration to rats (1 mg/kg dose), allowing to obtain high prodrug bioavailability and prolonged residence in the cerebrospinal fluid, showing AUC (Area Under Concentration) values (108.5 ± 3.9 μg∙mL -1 ∙min) up to 30 times over those of Fer free drug, after its intravenous/nasal administration (3.3 ± 0.3/5.16 ± 0.20 μg∙mL -1 ∙min, respectively) at the same dose. Chitosan presence further improved the prodrug brain uptake., Conclusions: Nasal administration of prodrug-loaded SLMs can be proposed as a noninvasive approach for neurodegenerative disease therapy.

O-Desmethylvenlafaxine (desvenlafaxine, ODV) is a recently approved antidepressant which in some clinical studies failed to meet a satisfactory end-point. The aim of this study was to prepare a series of phenolic esters of ODV and evaluate their potential as ODV prodrugs with improved brain uptake. Fifteen phenolic esters (compounds 1a–o) were synthesized and their pharmacokinetic profiles evaluated in rat. The four compounds producing the highest relative bioavailability of ODV in rat (compounds 1c, 1e, 1n, 1o) were then studied to evaluate their brain uptake. Of these four compounds, compound 1n (the piperonylic acid ester of ODV) demonstrated the highest Cmax of ODV both in the rat hypothalamus and total brain. Finally the pharmacokinetics of 1n were evaluated in beagle dog where the increase in relative bioavailability of ODV was found to be as great as in rat. This high relative bioavailability of ODV coupled with its good brain penetration make 1n the most promising candidate for development as an ODV prodrug.