The relationship between the rigidity of the liposomal membrane and the absorption of insulin after nasal administration of liposomes modified with an enhancer containing insulin in rabbits

Insulin Delivery to the Brain via the Nasal Route: Unraveling the Potential for Alzheimer's Disease Therapy

This comprehensive review delves into the potential of intranasal insulin delivery for managing Alzheimer's Disease (AD) while exploring the connection between AD and diabetes mellitus (DM). Both conditions share features of insulin signalling dysregulation and oxidative stress that accelerate inflammatory response. Given the physiological barriers to brain drug delivery, including the blood-brain barrier, intranasal administration emerges as a non-invasive alternative. Notably, intranasal insulin has shown neuroprotective effects, impacting Aβ clearance, tau phosphorylation, and synaptic plasticity. In preclinical studies and clinical trials, intranasally administered insulin achieved rapid and extensive distribution throughout the brain, with optimal formulations exhibiting minimal systemic circulation. The detailed mechanism of insulin transport through the nose-to-brain pathway is elucidated in the review, emphasizing the role of olfactory and trigeminal nerves. Despite promising prospects, challenges in delivering protein drugs from the nasal cavity to the brain remain, including enzymes, tight junctions, mucociliary clearance, and precise drug deposition, which hinder its translation to clinical settings. The review encompasses a discussion of the strategies to enhance the intranasal delivery of therapeutic proteins, such as tight junction modulators, cell-penetrating peptides, and nano-drug carrier systems. Moreover, successful translation of nose-to-brain drug delivery necessitates a holistic understanding of drug transport mechanisms, brain anatomy, and nasal formulation optimization. To date, no intranasal insulin formulation has received regulatory approval for AD treatment. Future research should address challenges related to drug absorption, nasal deposition, and the long-term effects of intranasal insulin. In this context, the evaluation of administration devices for nose-to-brain drug delivery becomes crucial in ensuring precise drug deposition patterns and enhancing bioavailability.

An overview of in vitro and in vivo techniques for characterization of intranasal protein and peptide formulations for brain targeting

The surge in neurological disorders necessitates innovative strategies for delivering active pharmaceutical ingredients to the brain. The non-invasive intranasal route has emerged as a promising approach to optimize drug delivery to the central nervous system by circumventing the blood-brain barrier. While the intranasal approach offers numerous advantages, the lack of a standardized protocol for drug testing poses challenges to both in vitro and in vivo studies, limiting the accurate interpretation of nasal drug delivery and pharmacokinetic data. This review explores the in vitro experimental assays employed by the pharmaceutical industry to test intranasal formulation. The focus lies on understanding the diverse techniques used to characterize the intranasal delivery of drugs targeting the brain. Parameters such as drug release, droplet size measurement, plume geometry, deposition in the nasal cavity, aerodynamic performance and mucoadhesiveness are scrutinized for their role in evaluating the performance of nasal drug products. The review further discusses the methodology for in vivo characterization in detail, which is essential in evaluating and refining drug efficacy through the nose-to-brain pathway. Animal models are indispensable for pre-clinical drug testing, offering valuable insights into absorption efficacy and potential variables affecting formulation safety. The insights presented aim to guide future research in intranasal drug delivery for neurological disorders, ensuring more accurate predictions of therapeutic efficacy in clinical contexts.

Regulation of Nanoliposome Rigidity and Bioavailability of Oligomeric Proanthocyanidin with Phytosterols Containing Different C3 Branches

The rigidity of nanoliposomes significantly influences their physical stability and in vitro and in vivo behaviors (e.g., cellular uptake, blood circulation, biodistribution, etc.). This study aimed to quantify the rigidity of the nanoliposomes composed of phytosterol with varying C3 branches and phospholipids (DPPC, DOPC) using atomic force microscopy. Young's modulus, determined by the Shell model, effectively differentiated between mechanical differences in nanoliposomes with varying components and component structure and phase states. FTIR results indicated that P-SG exhibited the highest Young's modulus (175.98 ± 10.53 MPa) due to the hydrogen bond between the glucose residue of steryl glycosides (SGs) and the phospholipid polar head. However, the rigidity of DOPC nanoliposomes was not significantly different due to the unsaturated bond. The addition of oligomeric proanthocyanidin (OPC) did not change the order of rigidity among the nanoliposomes, with P-SG-OPC having the highest Young's modulus (126.27 ± 2.06 MPa). In the simulated gastrointestinal tract experiment, P-SG-OPC exhibited the greatest stability, with minimal particle aggregation. Cellular uptake experiments revealed that DPPC nanoliposomes with high rigidity had optimal endocytosis, while DOPC nanoliposome uptake was independent of rigidity. In melanin production inhibition tests, the inhibitory effect correlated directly with Young's modulus and P-SG-OPC had the best inhibitory effect on melanin generation. Our findings in this study provide valuable insights into the design and optimization of nanoliposomes for the efficient delivery of active substances, offering potential solutions for improving the efficacy of drug delivery systems.

Extracellular Vesicles from Mesenchymal Stem Cells: Towards Novel Therapeutic Strategies for Neurodegenerative Diseases

Neurodegenerative diseases are fatal disorders of the central nervous system (CNS) which currently lack effective treatments. The application of mesenchymal stem cells (MSCs) represents a new promising approach for treating these incurable disorders. Growing evidence suggest that the therapeutic effects of MSCs are due to the secretion of neurotrophic molecules through extracellular vesicles. The extracellular vesicles produced by MSCs (MSC-EVs) have valuable innate properties deriving from parental cells and could be exploited as cell-free treatments for many neurological diseases. In particular, thanks to their small size, they are able to overcome biological barriers and reach lesion sites inside the CNS. They have a considerable pharmacokinetic and safety profile, avoiding the critical issues related to the fate of cells following transplantation. This review discusses the therapeutic potential of MSC-EVs in the treatment of neurodegenerative diseases, focusing on the strategies to further enhance their beneficial effects such as tracking methods, bioengineering applications, with particular attention to intranasal delivery as a feasible strategy to deliver MSC-EVs directly to the CNS in an effective and minimally invasive way. Current progresses and limiting issues to the extent of the use of MSC-EVs treatment for human neurodegenerative diseases will be also revised.

A novel strategy for production of liraglutide precursor peptide and development of a new long-acting incretin mimic

Nowadays, a small number of incretin mimics are used to treat type 2 diabetes mellitus (T2DM) due to their longer half-life. The present study aimed to introduce a novel method for producing the liraglutide precursor peptide (LPP) and developing a potentially new incretin mimic. Here, human αB-crystallin (αB-Cry) was ligated to the LPP at the gene level, and the gene construct was expressed in Escherichia coli with a relatively good efficiency. The hybrid protein (αB-lir) was then purified by a precipitation method followed by anion exchange chromatography. After that, the peptide was released from the carrier protein by a chemical cleavage method yielding about 70%. The LPP was then purified by gel filtration chromatography, and HPLC estimated its purity to be about 98%. Also, the molecular mass of the purified peptide was finally confirmed by mass spectroscopy analysis. Assessment of the secondary structures suggested a dominant α-helical structure for the LPP and a β-sheet rich structure for the hybrid protein. The subcutaneous injection of the LPP and the αB-lir hybrid protein significantly reduced the blood sugar levels in healthy and diabetic mice and stimulated insulin secretion. Also, the hybrid protein exerts its bioactivities more effectively than the LPP over a relatively longer period of time. The results of this study suggested a novel method for the easy and cost-effective production of the LPP and introduced a new long-acting incretin mimic that can be potentially used for the treatment of T2DM patients.

Nanotechnologies for the delivery of biologicals: Historical perspective and current landscape

Biological macromolecule-based therapeutics irrupted in the pharmaceutical scene generating a great hope due to their outstanding specificity and potency. However, given their susceptibility to degradation and limited capacity to overcome biological barriers new delivery technologies had to be developed for them to reach their targets. This review aims at analyzing the historical seminal advances that shaped the development of the protein/peptide delivery field, along with the emerging technologies on the lead of the current landscape. Particularly, focus is made on technologies with a potential for transmucosal systemic delivery of protein/peptide drugs, followed by approaches for the delivery of antigens as new vaccination strategies, and formulations of biological drugs in oncology, with special emphasis on mAbs. Finally, a discussion of the key challenges the field is facing, along with an overview of prospective advances are provided.

Intranasal Nanoparticulate Systems as Alternative Route of Drug Delivery

There is always a need for alternative and efficient methods of drug delivery. The nasal cavity can be considered as a non-invasive and efficient route of administration. It has been used for local, systemic, brain targeting, and vaccination delivery. Although many intranasal products are currently available on the market, the majority is used for local delivery with fewer products available for the other targets. As nanotechnology utilization in drug delivery has rapidly spread out, the nasal delivery has become attractive as a promising approach. Nanoparticulate systems facilitate drug transportation across the mucosal barrier, protect the drug from nasal enzyme degradation, enhance the delivery of vaccines to the lymphoid tissue of the nasal cavity with an adjuvant activity, and offer a way for peptide delivery into the brain and the systemic circulation, in addition to their potential for brain tumor treatment. This review article aims at discussing the potential benefit of the intranasal nanoparticulate systems, including nanosuspensions, lipid and surfactant, and polymer-based nanoparticles as regards productive intranasal delivery. The aim of this review is to focus on the topicalities of nanotechnology applications for intranasal delivery of local, systemic, brain, and vaccination purposes during the last decade, referring to the factors affecting delivery, regulatory aspects, and patient expectations. This review further identifies the benefits of applying the Quality by Design approaches (QbD) in product development. According to the reported studies on nanotechnology-based intranasal delivery, potential attention has been focused on brain targeting and vaccine delivery with promising outcomes. Despite the significant research effort in this field, nanoparticle-based products for intranasal delivery are not available. Thus, further efforts are required to promote the introduction of intranasal nanoparticulate products that can meet the requirements of regulatory affairs with high patient acceptance.

Nanotechnology in Insulin Delivery for Management of Diabetes

Diabetes is a group of diseases characterized by hyperglycemia and originating from the deficiency or resistance to insulin, or both. Ultimately, the most effective treatment for patients with diabetes involves subcutaneous injections of insulin. However, this route of administration is often painful and inconvenient, as most patients will have to selfadminister it at least twice a day for the rest of their lives. Also, infection, insulin precipitation, and either lipoatrophy or lipohypertrophy are frequently observed at the site of injection. To date, several alternative routes of insulin administration have been explored, including nasal, pulmonary and oral. Although the delivery of insulin is an ideal route for diabetic patients, several limitations have to be overcome such as the rapid degradation of insulin in gastric fluid and low oral bioavailability. Numerous strategies have been carried out to improve these limited parameters such as the use of enzyme inhibitors, absorption enhancers, mucoadhesive polymers and chemical modification for receptor-mediated absorption. Also, insulin-loaded nanocarriers bypass several physiological barriers. This current review focuses on the various barriers existing in the delivery of insulin through the oral route and the strategies undertaken so far to overcome those obstacles using nanocarriers as a potential vehicle of insulin.

Residence time and uptake of porous and cationic maltodextrin-based nanoparticles in the nasal mucosa: Comparison with anionic and cationic nanoparticles

Different types of biodegradable nanoparticles (NP) have been studied as nasal mucosa cell delivery systems. These nanoparticles need to strongly interact with mucosa cells to deliver their payload. However, only a few simultaneous comparisons have been made and it is therefore difficult to determine the best candidate. Here we compared 5 types of nanoparticles with different surface charge (anionic or cationic) and various inner compositions as potential vectors: cationic and anionic liposomes, cationic and anionic PLGA (Poly Lactic co-Glycolic Acid) NP and porous and cationic maltodextrin NP (cationic surface with an anionic lipid core: NPL). We first quantified their nasal residence time after nasal administration in mice using in vivo live imaging and NPL showed the longest residence time. In vitro endocytosis on mucosal cells (airway epithelial cells, macrophages and dendritic cells) using labeled nanoparticles were performed by flow cytometry and confocal microscopy. Among the 5 nanoparticles, NPL were taken up to the greatest extent by the 3 different cell lines and the endocytosis mechanisms were characterized. Taken together, we observed that the nanoparticles' cationic surface charge is insufficient to improve mucosal residence time and cellular uptake and that the NPL are the best candidates to interact with airway mucosal cells.

Biophysical, biopharmaceutical and toxicological significance of biomedical nanoparticles

Understanding of interplay between nanoparticles physicochemical and biophysical properties, and their impact on pharmacokinetic biodistribution and toxicological properties help designing of appropriate nanoparticle products for biomedical applications.

Nasal-nanotechnology: revolution for efficient therapeutics delivery

CONTEXT

In recent years, nanotechnology-based delivery systems have gained interest to overcome the problems of restricted absorption of therapeutic agents from the nasal cavity, depending upon the physicochemical properties of the drug and physiological properties of the human nose.

OBJECTIVE

The well-tolerated and non-invasive nasal drug delivery when combined with the nanotechnology-based novel formulations and carriers, opens the way for the effective systemic and brain targeting delivery of various therapeutic agents. To accomplish competent drug delivery, it is imperative to recognize the interactions among the nanomaterials and the nasal biological environment, targeting cell-surface receptors, drug release, multiple drug administration, stability of therapeutic agents and molecular mechanisms of cell signaling involved in patho-biology of the disease under consideration.

METHODS

Quite a few systems have been successfully formulated using nanomaterials for intranasal (IN) delivery. Carbon nanotubes (CNTs), chitosan, polylactic-co-glycolic acid (PLGA) and PLGA-based nanosystems have also been studied in vitro and in vivo for the delivery of several therapeutic agents which shown promising concentrations in the brain after nasal administration.

RESULTS AND CONCLUSION

The use of nanomaterials including peptide-based nanotubes and nanogels (NGs) for vaccine delivery via nasal route is a new approach to control the disease progression. In this review, the recent developments in nanotechnology utilized for nasal drug delivery have been discussed.

Emerging micro- and nanotechnology based synthetic approaches for insulin delivery

Insulin is essential for type 1 and advanced type 2 diabetics to maintain blood glucose levels and prolong lives. The traditional administration requires frequent subcutaneous insulin injections that are associated with poor patient compliance, including pain, local tissue necrosis, infection, and nerve damage. Taking advantage of emerging micro- and nanotechnologies, numerous alternative strategies integrated with chemical approaches for insulin delivery have been investigated. This review outlines recent developments in the controlled delivery of insulin, including oral, nasal, pulmonary, transdermal, subcutaneous and closed-loop insulin delivery. Perspectives from new materials, formulations and devices at the micro- or nano-scales are specifically surveyed. Advantages and limitations of current delivery methods, as well as future opportunities and challenges are also discussed.

A novel fatty acid lipophilic index and risk of CHD in US men: the health professionals follow-up study

Few epidemiological studies have examined the association between an overall fatty acid (FA) profile and CHD risk. The aim of the present study was to examine a novel index that summarises individual FA levels based on FA affinity and fluidity in relation to CHD risk in men. In a prospective nested case–control study, FA in plasma and erythrocytes were measured in 459 CHD cases and 879 matched controls. Lipophilic index (LI) was computed by summing the products between FA levels and melting point of each FA to reflect the overall FA lipophilicity. Among controls, higher plasma LI was significantly correlated with adverse profiles of blood lipids, inflammatory markers and adiponectin. After multivariate adjustment for age, smoking, BMI and other CHD risk factors, plasma LI was significantly associated with an increased risk of CHD: the relative risk was 1·61 (95% CI 1·03, 2·53; P for trend¼0·04) comparing extreme quintiles. This association was attenuated to 1·21 (95% CI 0·48, 3·09; P for trend¼0·77) after adjusting for plasma levels of total trans-FA, long-chain n-3 FA and polyunsaturated:saturated fat ratio. Erythrocyte LI was not significantly associated with CHD risk. The present data indicate that a novel LI is associated with an adverse profile of cardiovascular risk markers and increased risk of CHD in men; its usefulness as a complement of individual FA in assessing disease risk needs to be elucidated in future studies.

The effect of polymer coatings on physicochemical properties of spray-dried liposomes for nasal delivery of BSA

This work describes the development of spray dried polymer coated liposomes composed of soy phosphatidylcholine (SPC) and phospholipid dimyristoyl phosphatidylglycerol (DMPG) coated with alginate, chitosan or trimethyl chitosan (TMC), that are able to penetrate through the nasal mucosa and offer enhanced penetration over uncoated liposomes when delivered as a dry powder. All the liposome formulations, loaded with BSA as model antigen, were spray-dried to obtain powder size and liposome size in a suitable range for nasal delivery. Although coating resulted in some reduction in encapsulation efficiency, levels were still maintained between 60% and 69% and the structural integrity of the entrapped protein and its release characteristics were maintained. Coating with TMC gave the best product characteristics in terms of entrapment efficiency, glass transition (T(g)) and mucoadhesive strength, while penetration of nasal mucosal tissue was very encouraging when these liposomes were administered as dispersions although improved results were observed for the dry powders.

Liposomal delivery of proteins and peptides

INTRODUCTION

A number of delivery issues exist for biotech molecules including peptides, proteins and gene-based medicines that now make up over 60% of the drug pipeline. The problems comprise pharmaceutical ad biopharmaceutical issues. One of the common approaches to overcome these issues is the use of a carrier and liposomes as carriers have been investigated extensively over the last decade.

AREAS COVERED

The review has been discussed in terms of formulation and preclinical development studies and in vivo studies encompassing different delivery routes including parenteral, oral, buccal, pulmonary, intranasal, ocular and transdermal involving liposomes as carriers. Important research findings have been tabulated under each side heading and an expert opinion has been summarised for each delivery route.

EXPERT OPINION

The conclusion and expert opinion - conclusion sections discuss in detail troubleshooting aspects related to the use of liposomes as carriers for delivery of biopharmaceutical moieties and scrutinises the aspects behind the absence of a protein/peptide-containing liposome in market.

Development, optimization and in vitro evaluation of alginate mucoadhesive microspheres of carvedilol for nasal delivery

The present research work was aimed at development and optimization of alginate mucoadhesive microspheres of carvedilol for nasal delivery to avoid first pass metabolism and to improve the therapeutic efficacy in the treatment of hypertension and angina pectoris. The microspheres were prepared by a water-in-oil (w/o) emulsification technique. A 2(3) factorial design was employed with drug : polymer ratio, calcium chloride concentration and cross-linking time as independent variables while particle size of the microspheres and in vitro mucoadhesion were the dependent variables. Regression analysis was performed to identify the best formulation conditions. Particle size was analysed by dynamic laser light diffraction technique and found to be in the range of 26.36-54.32 microm, which is favourable for intranasal absorption. The shape and surface characteristics were determined by scanning electron microscopy (SEM) which depicted the spherical nature and nearly smooth surfaces of the microspheres. The percentage encapsulation efficiency was found to be in the range between 36.62-56.18. In vitro mucoadhesion was performed by adhesion number using sheep nasal mucosa and was observed in a range from 69.25-85.28. Differential scanning calorimetry and X-ray diffraction results indicated a molecular level dispersion of carvedilol in the microspheres. In vitro release studies in pH 6.2 phosphate buffer indicated non-Fickian or anomalous type of transport for the release of carvedilol from the microspheres.

Effects of polyamidoamine (PAMAM) dendrimers on the nasal absorption of poorly absorbable drugs in rats

The absorption enhancing effects of polyamidoamine (PAMAM) dendrimers with various concentrations and generations on the nasal absorption of fluorescein isothiocyanate-labeled dextran with an average molecular weight of 4400 (FD4) were initially studied in rats. PAMAM dendrimers with different generations improved the nasal absorption of FD4 and the absorption enhancing effects of PAMAM dendrimers were generation dependent. The rank order of absorption enhancement effects of PAMAM dendrimers was G3>G2>G1>G0. The absorption enhancing effects of PAMAM dendrimers were shown to be concentration dependent for the same generation of PAMAM dendrimers. The nasal membrane toxicity of these PAMAM dendrimers was evaluated by measuring the release of protein and lactate dehydrogenase (LDH) in nasal cavity lavage fluid. PAMAM dendrimers with higher generations and concentrations caused some membrane damage to the nasal tissues, but it was much less than the damage caused by sodium deoxycholate as a positive control. Based on the consideration between the efficacy and safety of PAMAM dendrimers, 1% (w/v) G3 dendrimer with high effectiveness and low toxicity was considered to be a best absorption enhancer for improving the nasal absorption of FD4. 1% (w/v) G3 dendrimer also improved the nasal absorption of macromolecular compounds and drugs including FD10, FD70, insulin and calcitonin. Finally, we measured the zeta potentials of drug solutions with or without PAMAM dendrimers to elucidate their absorption enhancing mechanisms. The zeta potentials of model drug solutions changed to positive by the addition of 1% (w/v) G3 dendrimer. This changing might trigger the absorption enhancing effects of PAMAM dendrimers on the nasal absorption of FDs, insulin and calcitonin, as the first step of mechanisms. In conclusion, 1% (w/v) G3 dendrimer is a promising absorption enhancer for improving the nasal absorption of FDs, insulin and calcitonin without any membrane damage to the nasal tissues.

Improved absorption of salmon calcitonin by ultraflexible liposomes through intranasal delivery

The objective of this work was to explore the potential of ultraflexible liposomes as carriers for improving the absorption of salmon calcitonin (sCT) through intranasal administration. The average diameters of positively charged ultraflexible liposomes ranged from about 73 to 99 nm, while those of negatively charged ones were 114 and 157.6 nm, respectively. The content of sodium deoxycholate in liposomes markedly affected the size and encapsulated efficiency of liposomes. The absorption of sCT through intranasal administration was evaluated by hypocalcemic efficacy in rats. The total Ca decrease D% of sCT-loaded ultraflexible liposomes with positive and negative charges were significantly bigger than that of sCT solution, while there was no significant difference in the hypocalcemic efficacy between plain liposome and sCT solution. Unexpectedly, the hypocalcemic efficacy of sCT-loaded ultraflexible liposomes with positive charges was not significantly better than those with negative charges. The decrease rate and extent of the serum calcium level for subcutaneous injection of sCT solution were almost equivalent to those for intranasal administration of negatively and positively charged ultraflexible liposomes within the first 2h, indicating that the ultraflexible liposomes could quickly enhance the penetration of the drug during their residence in the nasal cavity. The results of the toxicity of sCT-loaded ultraflexible liposomes to nasal mucosa demonstrated that the ultraflexible liposomes exerted slight toxicity on the nasal mucosa. On an overall evaluation, the ultraflexible liposomes may be a useful vehicle for intranasal delivery of sCT.

Acyclovir liposomes for intranasal systemic delivery: development and pharmacokinetics evaluation

Intranasal route is one of the most attractive routes for distributing drugs to systemic circulation. Liposomes are used as biocompatible carriers to improve delivery properties across nasal mucosa. The objective of the present study was to formulate acyclovir liposomes and partition into poly-N-vinyl-2-pyrrolidone. Entrapment efficiency showed that multilamellar and unilamellar liposomes were 43.2% +/- 0.83 and 21% +/- 1.01, respectively. The bioavailability of acyclovir from nasal mucoadhesive gel was 60.72% compared with intravenous route. The use of liposomes acyclovir and mucoadhesive gel not only promoted the prolonged contact between the drug and the absorptive sites in the nasal cavity, but also facilitated direct absorption through the nasal mucosa.

Effect of cell-penetrating peptides on the nasal absorption of insulin

The goal of this study was to evaluate whether cell-penetrating peptides (CPPs) affect the nasal absorption of insulin. L- or D-forms of penetratin, or the L- or D-forms of octaarginine (L- or D-R8), was used as first time for nasal insulin delivery. Furthermore, the concentration of lactate dehydrogenase (LDH) in nasal lavage fluid was determined and a histopathological study of nasal respiratory epithelium was conducted. CPPs dramatically increased nasal insulin absorption, and it was more pronounced for L- and D-penetratin than L- or D-R8. L-penetratin was the most effective promoter of insulin absorption compared with others CPPs. A dose-dependent relationship of L-penetratin and insulin bioavailability was statically significant. The pharmacological availability and bioavailability of nasally administered insulin was up to 76.7% and 50.7% relative to the subcutaneous route, respectively. In contrast, increasing the D-penetratin concentration decreased the efficiency of nasal insulin absorption. There was no significant difference in the release of LDH in nasal lavage fluid and the integrity of nasal respiratory epithelium when L-penetratin was present. In conclusion, these data demonstrate that L-penetratin markedly increased the permeability of insulin across the nasal membrane without causing detectable damage to the integrity of cells in the nasal respiratory mucosa.

A study of rivastigmine liposomes for delivery into the brain through intranasal route

The present study is mainly aimed at delivering a drug into the brain via the intranasal route using a liposomal formulation. For this purpose, rivastigmine, which is used in the management of Alzheimer's disease, was selected as a model drug. Conventional liposomes were formulated by the lipid layer hydration method using cholesterol and soya lecithin as lipid components. The concentration of rivastigmine in brain and plasma after intranasal liposomes, free drug and per oral administration was studied in rat models. A significantly higher level of drug was found in the brain with intranasal liposomes of rivastigmine compared to the intranasal free drug and the oral route. Intranasal liposomes had a longer half-life in the brain than intranasally or orally administered free drug. Delivering rivastigmine liposomes through the intranasal route for the treatment of Alzheimer's disease might be a new approach to the management of this condition.

Novel ultra-deformable vesicles entrapped with bleomycin and enhanced to penetrate rat skin

Beta-sitosterol 3-beta-D-glucoside (Sit-G), an absorption enhancer, was incorporated into ultra-deformable vesicles containing bleomycin to attenuate drug toxicity in human keratinocytes. The presence of Sit-G increased drug entrapment and improved in vitro stability of ultra-deformable vesicles. Confocal laser scanning microscopy revealed the extent to which Sit-G facilitated the penetration of ultra-deformable vesicles containing fluorescent probes into rat skin upon non-occlusive topical application. Furthermore, treatment with preparations incorporating Sit-G resulted in elevated epidermal and dermal concentrations of bleomycin. Ultra-deformable formulation contained Sit-G maintained flexibility for penetration through the skin, increased entrapment efficiency of bleomycin and stability in vitro, and significantly increased distribution of bleomycin in epidermis and dermis compared with those without Sit-G.

Cholesteryl hemisuccinate as a membrane stabilizer in dipalmitoylphosphatidylcholine liposomes containing saikosaponin-d

In the present study, cholesteryl hemisuccinate (CHEMS) was evaluated for use as a membrane stabilizer in dipalmitoylphosphatidylcholine (DPPC) liposomes. Differential scanning calorimetry (DSC) and a calcein release study showed that CHEMS was more effective than cholesterol (CHOL) in increasing DPPC membrane stability. The findings of Fourier transform infrared spectroscopy (FT-IR) also suggested that CHEMS interacts with DPPC via both hydrogen bonding and electrostatic interaction. More importantly, CHEMS did not interact with saikosaponin-d (SSD), a triterpene saponin from Bupleurum species, unlike CHOL. SSD-containing liposomes with DPPC, CHEMS and DSPE-PEG could greatly decrease the hemolytic activity of SSD. This study demonstrated that CHEMS has more stabilization ability than CHOL since CHEMS may exhibit both hydrogen bond interaction and electrostatic interaction with DPPC membrane while CHOL only has hydrogen bond interaction, resulting in stable and low-hemolytic SSD-liposomes.

beta-Sitosterol, beta-Sitosterol Glucoside, and a Mixture of beta-Sitosterol and beta-Sitosterol Glucoside Modulate the Growth of Estrogen-Responsive Breast Cancer Cells In Vitro and in Ovariectomized Athymic Mice

We hypothesized that the phytosterols beta-sitosterol (BSS), beta-sitosterol glucoside (BSSG), and Moducare (MC; BSS:BSSG = 99:1) could modulate the growth of estrogen-dependent human breast cancer cells in vitro and in vivo. The present study evaluated the estrogenic and antiestrogenic effects of BSS, BSSG, and MC (0.001 to 150 micromol/L) on the proliferation of Michigan Cancer Foundation 7 (MCF-7) cells in vitro. Both BSS (>1 micromol/L) and MC (>50 micromol/L) increased MCF-7 cell proliferation. Treatment with 150 micro mol/L of BSS and MC increased cell growth by 2.4 and 1.5 times, respectively, compared to the negative control (NC) group. However, BSSG had no effect at the concentrations tested. The effects of dietary BSS, BSSG, and MC on the growth of MCF-7 cells implanted in ovariectomized athymic mice were also evaluated. Estrogenic effects of the phytosterols were evaluated in the NC, BSS, BSSG, and MC treatment groups, and antiestrogenic effects were evaluated in the 17 beta-estradiol (E(2)), E(2) + BSS, E(2) + BSSG, and E(2) + MC treatment groups. Mice were treated with dietary BSS (9.8 g/kg AIN93G diet), BSSG (0.2 g/kg diet), or MC (10.0 g/kg diet) for 11 wk. Dietary BSS, BSSG, and MC did not stimulate MCF-7 tumor growth. However, dietary BSS, BSSG, and MC reduced E(2)-induced MCF-7 tumor growth by 38.9% (P < 0.05), 31.6% (P = 0.08), and 42.13% (P < 0.05), respectively. The dietary phytosterols lowered serum E(2) levels by 35.1, 30.2, and 36.5% in the E(2) + BSS, E(2) + BSSG, and E(2) + MC groups, respectively (P < 0.05), compared to that of the E(2) treatment group. Estrogen-responsive pS2 mRNA expression in tumors did not differ among groups, but expression of the antiapoptotic marker B-cell lymphoma/leukemia-2 (bcl-2) in tumors from the E(2) + MC group was downregulated, compared to that of the E(2) treatment group. In summary, BSS and MC stimulated MCF-7 cell growth in vitro. Although BSSG comprises only 1% of MC, BSSG made MC less estrogenic than BSS alone in vitro. However, dietary BSS and MC protected against E(2)-stimulated MCF-7 tumor growth and lowered circulating E(2) levels.

Absorption enhancers for nasal drug delivery

This paper describes the basic concepts for the transmucosal delivery of drugs, and in particular the use of the nasal route for delivery of challenging drugs such as polar low-molecular-weight drugs and peptides and proteins. Strategies for the exploitation of absorption enhancers for the improvement of nasal delivery are discussed, including consideration of mechanisms of action and the correlation between toxic effect and absorption enhancement. Selected enhancer systems, such as cyclodextrins, phospholipids, bioadhesive powder systems and chitosan, are discussed in detail. Examples of the use of these enhancers in preclinical and clinical studies are given. Methods for assessing irritancy and damage to the nasal membrane from the use of absorption enhancers are also described. Finally, the mucosal use of absorption enhancers (chitosan) for the improved nasal delivery of vaccines is reported with reference to recent phase I/II clinical studies.

Oral colon-specific drug delivery for bee venom peptide: development of a coated calcium alginate gel beads-entrapped liposome

Colon-specific drug delivery systems (CDDSs) can be used to improve the bioavailability of protein and peptide drugs through the oral route. A novel formulation for oral administration using coated calcium alginate gel beads-entrapped liposome and bee venom peptide as a model drug has been investigated for colon-specific drug delivery in vitro. Drug release studies under conditions mimicking stomach to colon transit have shown that the drug was protected from being released completely in the physiological environment of the stomach and small intestine. The release rate of bee venom from the coated calcium alginate gel beads-entrapped liposome was dependent on the concentration of calcium and sodium alginate, the amount of bee venom in the liposome, as well as the coating. Furthermore, a human gamma-scintigraphy technique was used in vivo to determine drug delivery more precisely. The colonic arrival time of the tablets was found to be 4-5 h. The results clearly demonstrated that the coated calcium alginate gel beads-entrapped liposome is a potential system for colon-specific drug delivery.

Permeability issues in nasal drug delivery

The nasal route is one of the most permeable and highly vascularized site for drug administration ensuring rapid absorption and onset of therapeutic action. It has been potentially explored as an alternative route for drugs with poor bioavailability and for the delivery of biosensitive and high molecular weight (MW) compounds such as proteins, peptides, steroids, vaccines, and so on. This review discusses the major factors affecting the permeability of drugs or biomolecules through the nasal mucosa, including biological, formulation and device-related factors. This information could potentially help to achieve desired plasma concentrations of drugs without compromising or altering the normal physiology of the nasal cavity.

Preparation of desmopressin-containing liposomes for intranasal delivery

The loading and leakage characteristics of the desmopressin-containing liposomes and the effect of liposomes on the nasal mucosa permeation and antidiuresis of desmopressin were investigated. Higher loading efficiency of desmopressin for positively charged liposomes than negatively charged liposomes was obtained, and neutral liposomes resulted in a similar loading efficiency as that of positively charged liposomes. Greater leakage of desmopressin from negatively charged liposomes than from positively charged and neutral liposomes was shown. The increase of permeability of desmopressin through the nasal mucosa indicated positively charged liposomes>negatively charged liposomes>solution. It was suggested that the enhanced contact time of positively charged liposomes with negatively charged nasal mucosa led to a high local desmopressin concentration on the penetration site to promote an effective penetration of desmopressin through the nasal mucosa. The desmopressin antidiuresis result after intranasal administration was in good agreement with the permeability result in the order of positively charged liposomes>negatively charged liposomes>solution. One of the mechanisms for the explanation of the best result on the enhancement of antidiuresis for positively charged liposomes may be the bioadhesive effect of the liposomes on the negatively charged nasal mucosa.