Effect of polysorbate 80 on the intranasal absorption and brain distribution of tetramethylpyrazine phosphate in rats

Development of nanomedicines for the treatment of Alzheimer's disease: Raison d'être, strategies, challenges and regulatory aspects

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by progressive loss of memory. Presently, AD is challenging to treat with current drug therapy as their delivery to the brain is restricted by the presence of the blood-brain barrier. Nanomedicines, due to their size, high surface volume ratio, and ease of tailoring drug release characteristics, showed their potential to treat AD. The nanotechnology-based formulations for brain targeting are expected to enter the market in the near future. So, regulatory frameworks are required to ensure the quality, safety, and effectiveness of the nanomedicines to treat AD. In this review, we discuss different strategies, in-vitro blood-brain permeation models, in-vivo permeation assessment, and regulatory aspects for the development of nanomedicine to treat AD.

Enhanced brain distribution of Ginsenoside F1 via intranasal administration in combination with absorption enhancers

Ginsenoside F1 (GF1) is a potential drug candidate for the treatment of Alzheimer's disease. Nevertheless, its low oral bioavailability and poor solubility limit clinical application. By utilizing either a direct or indirect approach, intranasal administration is a non-invasive drug delivery method that can deliver drugs to the brain rapidly. But large molecule drug delivered to the brain through intranasal administration may be insufficient to reach required concentration for therapeutic effect. In this study, using GF1 as a model drug, the feasibility of intranasal administration in combination with absorption enhancers to increase brain distribution of GF1 was explored. First of all, the appropriate absorption enhancers were screened by in situ nasal perfusion study. GF1-HP-β-CD inclusion complex was prepared and characterized. Thereafter, in vivo absorption of GF1 after intranasal or intravenous administration of its inclusion complex with/without absorption enhancers was investigated, and safety of the formulations was evaluated. The results showed that 2% Solutol HS 15 was a superior absorption enhancer. HP-β-CD inclusion complex improved GF1 solubility by 150 fold. Following intranasal delivery, the absolute bioavailability of inclusion complex was 46%, with drug brain targeting index (DTI) 247% and nose-to-brain direct transport percentage (DTP) 58%. Upon further addition of 2% Solutol HS 15, the absolute bioavailability was increased to 75%, with DTI 315% and DTP 66%. Both nasal cilia movement and biochemical substances (total protein and lactate dehydrogenase) leaching studies demonstrated 2% Solutol HS 15 was safe to the nasal mucosa. In conclusion, intranasal administration combining with safe absorption enhancers is an effective strategy to enhance drug distribution in the brain, showing promise for treating disorders related to the central nervous system.

A Historical Review of Brain Drug Delivery

The history of brain drug delivery is reviewed beginning with the first demonstration, in 1914, that a drug for syphilis, salvarsan, did not enter the brain, due to the presence of a blood-brain barrier (BBB). Owing to restricted transport across the BBB, FDA-approved drugs for the CNS have been generally limited to lipid-soluble small molecules. Drugs that do not cross the BBB can be re-engineered for transport on endogenous BBB carrier-mediated transport and receptor-mediated transport systems, which were identified during the 1970s-1980s. By the 1990s, a multitude of brain drug delivery technologies emerged, including trans-cranial delivery, CSF delivery, BBB disruption, lipid carriers, prodrugs, stem cells, exosomes, nanoparticles, gene therapy, and biologics. The advantages and limitations of each of these brain drug delivery technologies are critically reviewed.

Mucoadhesive meloxicam-loaded nanoemulsions: Development, characterization and nasal applicability studies

Intranasally administered non-steroidal anti-inflammatory drugs (NSAIDs) offer an innovative opportunity in the field of pain management. Combination of the nasal physiological advantages such as the rich vascularization and large absorption area along with novel nanomedical formulations can fulfill all the necessary criteria of an advanced drug delivery system. Nanoemulsions represent a versatile formulation approach suitable for nasal drug delivery by increasing the absorption and the bioavailability of many drugs for systemic and nose-to-brain delivery due to their stability, small droplet size and optimal solubilization properties. In this study we aimed to develop meloxicam (MX)-loaded mucoadhesive nanoemulsions and to investigate the nasal applicability of the optimized formulations. Our results indicated the optimized nanoemulsion formulation (MX-NE3) had a droplet size of 158.5 nm in monodisperse droplet size distribution (polydispersity index of 0.211). The surface charge was -11.2 mV, which helped with the colloidal stability upon dilution at simulated nasal conditions and storage. The high encapsulation efficiency (79.2%) mediated a 15-fold drug release and a 3-fold permeability increase at nasal conditions compared to the initial MX. Proper wetting properties associated with high mucoadhesion prosper the increased residence time on the surface of the nasal mucosa. No cytotoxic effect of the formulations was observed on NIH/3T3 mouse embryonic fibroblast cell lines, which supports the safe nasal applicability.

Surface Modification of Curcumin Microemulsions by Coupling of KLVFF Peptide: A Prototype for Targeted Bifunctional Microemulsions

Curcumin is one of the most promising natural therapeutics for use against Alzheimer’s disease. The major limitations of curcumin are its low oral bioavailability and difficulty in permeating the blood–brain barrier. Therefore, designing a delivery system of curcumin to overcome its limitations must be employed. KLVFF, a peptide known as an amyloid blocker, was used in this study as a targeting moiety to develop a targeted drug delivery system. A prototype of transnasal KLVFF conjugated microemulsions containing curcumin (KLVFF-Cur-ME) for the nose-to-brain delivery was fabricated. The KLVFF-Cur-ME was developed by a titration method. A conjugation of KLVFF was performed through a carbodiimide reaction, and the conjugation efficiency was confirmed by FTIR and DSC technique. KLVFD-Cur-ME was characterized for the drug content, globule size, zeta potential, and pH. A transparent and homogeneous KLVFF-Cur-ME is achieved with a drug content of 80.25% and a globule size of 76.1 ± 2.5 nm. The pH of KLVFF-Cur-ME is 5.33 ± 0.02, indicating non-irritation to nasal tissues. KLVFD-Cur-ME does not show nasal ciliotoxicity. An ex vivo diffusion study revealed that KLVFF-Cur-ME partitions the porcine nasal mucosa through diffusion, following the Higuchi model. This investigation demonstrates the successful synthesis of a bifunctional KLVFF-Cur-ME as a novel prototype to deliver anti-Aβ aggregation via an intranasal administration.

Formulation, Characterization, and Cytotoxicity Evaluation of Lactoferrin Functionalized Lipid Nanoparticles for Riluzole Delivery to the Brain

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with a very poor prognosis. Its treatment is hindered by a lack of new therapeutic alternatives and the existence of the blood-brain barrier (BBB), which restricts the access of drugs commonly used in ALS, such as riluzole, to the brain. To overcome these limitations and increase brain targeting, riluzole-loaded nanostructured lipid carriers (NLC) were prepared and functionalized with lactoferrin (Lf), facilitating transport across the BBB by interacting with Lf receptors expressed in the brain endothelium. NLC were characterized with respect to their physicochemical properties (size, zeta potential, polydispersity index) as well as their stability, encapsulation efficiency, morphology, in vitro release profile, and biocompatibility. Moreover, crystallinity and melting behavior were assessed by DSC and PXRD. Nanoparticles exhibited initial mean diameters between 180 and 220 nm and a polydispersity index below 0.3, indicating a narrow size distribution. NLC remained stable over at least 3 months. Riluzole encapsulation efficiency was very high, around 94-98%. FTIR and protein quantification studies confirmed the conjugation of Lf on the surface of the nanocarriers, with TEM images showing that the functionalized NLC presented a smooth surface and uniform spherical shape. An MTT assay revealed that the nanocarriers developed in this study did not cause a substantial reduction in the viability of NSC-34 and hCMEC/D3 cells at a riluzole concentration up to 10 μM, being therefore biocompatible. The results suggest that Lf-functionalized NLC are a suitable and promising delivery system to target riluzole to the brain.

Preparation, characterization, and in vivo biodistribution study of intranasal 131I-clonazepam-loaded phospholipid magnesome as a promising brain delivery system: Biodistribution and pharmacokinetic behavior of intranasal 131I-Clonazepam loaded phospholipid magnesome as a potential brain targeting system

OBJECTIVE

Clonazepam (CP) is a potent long-acting nitrobenzodiazepine derivative that could be used for targeting peripheral benzodiazepine receptors. Phospholipid magnesome is a new vesicular nanosystem recently developed for brain targeting. Improving the uptake of ¹³¹I-CP to the brain might be effective for the diagnosis and/or radiotherapy of certain brain diseases and/or tumors.

METHODS

CP was radiolabeled with ¹³¹I using direct electrophilic substitution reaction. Quality control of ¹³¹I-CP was performed using different techniques. Different formulas of ¹³¹I-CP were prepared and characterized according to particle size and polydispersity index. The structural features of the optimized formula were then interpreted using transmission electron microscopy and scanning electron microscopy, whereas pharmacokinetic and in vivo behaviors were estimated using the intravenous and intranasal delivery routes.

RESULTS

The heart and blood demonstrated lower uptake of ¹³¹I-CP, which inevitably decreased the nontarget effects of radioiodine. Intranasally administered ¹³¹I-CP-loaded magnesomes (INMg) had noticeably higher brain uptake (7.1 ± 0.09%ID/g) with rapid onset of action within 5 min and effective pharmacokinetic behavior. INMg had a drug targeting efficiency and nose-to-brain direct transport percentage of 121.1% and 94.6%, respectively as well as a relative bioavailability of 441.04 ± 75.5%.

CONCLUSION

The present study showed that ¹³¹I-CP-loaded magnesomes can be a beneficial brain-targeting approach for improving the diagnosis and/or radiotherapy of certain brain diseases.

Polysorbate-Based Drug Formulations for Brain-Targeted Drug Delivery and Anticancer Therapy

Polysorbates (PSs) are synthetic nonionic surfactants consisting of polyethoxy sorbitan fatty acid esters. PSs have been widely employed as emulsifiers and stabilizers in various drug formulations and food additives. Recently, various PS-based formulations have been developed for safe and efficient drug delivery. This review introduces the general features of PSs and PS-based drug carriers, summarizes recent progress in the development of PS-based drug formulations, and discusses the physicochemical properties, biological safety, P-glycoprotein inhibitory properties, and therapeutic applications of PS-based drug formulations. Additionally, recent advances in brain-targeted drug delivery using PS-based drug formulations have been highlighted. This review will help researchers understand the potential of PSs as effective drug formulation agents.

Classical Active Ingredients and Extracts of Chinese Herbal Medicines: Pharmacokinetics, Pharmacodynamics, and Molecular Mechanisms for Ischemic Stroke

Stroke is a leading cause of death and disability worldwide, and approximately 87% of cases are attributed to ischemia. The main factors that cause ischemic stroke include excitotoxicity, energy metabolism disorder, Ca⁺ overload, oxidative damage, apoptosis, autophagy, and inflammation. However, no effective drug is currently available for the comprehensive treatment of ischemic stroke in clinical applications; thus, there is an urgent need to find and develop comprehensive and effective drugs to treat postischemic stroke. Traditional Chinese medicine (TCM) has unique advantages in treating ischemic stroke, with overall regulatory effects at multiple levels and on multiple targets. Many researchers have studied the effective components of TCMs and have achieved undeniable results. This paper reviews studies on the anticerebral ischemia effects of TCM monomers such as tetramethylpyrazine (TMP), dl-3-n-butylphthalide (NBP), ginsenoside Rg1 (Rg1), tanshinone IIA (TSA), gastrodin (Gas), and baicalin (BA) as well as effective extracts such as Ginkgo biloba extract (EGB). Research on the anticerebral ischemia effects of TCMs has focused mostly on their antioxidative stress, antiapoptotic, anti-inflammatory, proangiogenic, and proneurogenic effects. However, the research on the use of TCM to treat ischemic stroke remains incompletely characterized. Thus, we summarized and considered this topic from the perspective of pharmacokinetics, pharmacological effects, and mechanistic research, and we have provided a reference basis for future research and development on anticerebral ischemia TCM drugs.

Enhanced nose-to-brain delivery of tranilast using liquid crystal formulations

Intranasal administration is poised as a competent method in delivering drugs to the brain, because the nasal route has a direct link with the central nervous system bypassing the formidable blood-brain barrier. C₁₇-monoglycerol ester (MGE) and glyceryl monooleate (GMO) as liquid crystal (LC)-forming lipids possess desirable formulation characteristics as drug carriers for intranasally administered drugs. This study investigated the effect of LC formulations on the pharmacokinetics of tranilast (TL), a lipophilic model drug, and its distribution in the therapeutic target regions of the brain in rats. The anatomical biodistribution of LC formulations was monitored using micro-computed tomography tandem in vivo imaging systems. MGE and GMO effectively formed LC with suitable particle size, zeta potential, and viscosity supporting the delivery of TL to the brain. MGE and GMO LC formulations enhanced brain uptake by 10- to 12-fold and 2- to 2.4- fold, respectively, compared with TL solution. The olfactory bulb had the highest TL concentration and fluorescent signals among all the brain regions, indicating a direct nose-to-brain delivery pathway of LC formulations. LC-forming lipids, MGE and GMO, are potential biomaterials in formulations intended for intranasal administration.

Optimization of Curcumin Nanocrystals as Promising Strategy for Nose-to-Brain Delivery Application

Intranasal (IN) drug delivery is recognized to be an innovative strategy to deliver drugs to the Central Nervous System. One of the main limitations of IN dosing is the low volume of drug that can be administered. Accordingly, two requirements are necessary: the drug should be active at a low dosage, and the drug solubility in water must be high enough to accommodate the required dose. Drug nanocrystals may overcome these limitations; thus, curcumin was selected as a model drug to prepare nanocrystals for potential IN administration. With this aim, we designed curcumin nanocrystals (NCs) by using Box Behnken design. A total of 51 formulations were prepared by the sonoprecipitation method. Once we assessed the influence of the independent variables on nanocrystals' mean diameter, the formulation was optimized based on the desirability function. The optimized formulation was characterized from a physico-chemical point of view to evaluate the mean size, zeta potential, polidispersity index, pH, osmolarity, morphology, thermotropic behavior and the degree of crystallinity. Finally, the cellular uptake of curcumin and curcumin NCs was evaluated on Olfactory Ensheathing Cells (OECs). Our results showed that the OECs efficiently took up the NCs compared to the free curcumin, showing that NCs can ameliorate drug permeability.

Development of a microemulsion for encapsulation and delivery of gallic acid. The role of chitosan

A novel water-in-oil (W/O) microemulsion based on natural oils, namely extra virgin olive oil (EVOO) and sunflower oil (SO), in the presence of non-ionic surfactants was successfully formulated. The novel microemulsion was used as a carrier for gallic acid (GA) to assure its protection and efficacy upon nasal administration. The work presents evidence that this microemulsion can be used as a nasal formulation for the delivery of polar antioxidants, especially, after incorporation of chitosan (CH) in its aqueous phase. The structure of the system was studied by Small Angle X-ray Scattering (SAXS), Dynamic Light Scattering (DLS) and Electron Paramagnetic Resonance (EPR) spectroscopy techniques. By the addition of CH, the diameter of the microemulsion remained unaltered at 47 nm whereas after the incorporation of GA, micelles with 51 nm diameter were detected. The dynamic properties of the surfactant monolayer were affected by both the incorporation of CH and GA. Moreover, the antioxidant activity of the latter remained unaltered (99 %). RPMI 2650 cell line was used as the in vitro model for cell viability and for GA nasal epithelial transport studies after microemulsion administration. The results suggested that the nasal epithelial permeation of GA was enhanced, 3 h post administration, by the presence of 0.2 % v/v microemulsion in the culture medium. However, the concentration of the transported antioxidant in the presence of CH was higher indicating the polymer's effect on the transport of the GA. The study revealed that nasal administration of hydrophilic antioxidants could be used as an alternative route besides oral administration.