Niosomes for oral delivery of peptide drugs

Niosomes loading N-acetyl-L-cysteine for cancer treatment in vivo study

Scientists are seeking to find an effective treatment for tumors that has no side effects. N-Acetyl-l-cysteine (NAC) is a thiol compound extracted from garlic. Current study explores the potential of NAC-loaded niosomes (NAC-NIO) for tumor treatment in mice. NAC-loaded niosomes' efficiency, morphology, UV absorption, size distribution, zeta potential, release, and FTIR analysis were evaluated. For vivo study, 25 male BALB/c mice were divided to five groups: gp1 negative control (receive saline), gp2 positive control (tumor group), gp3 treated with NAC, gp4 treated with NAC-NIO at the same time of tumor injection, and gp5 treated with NAC-NIO after tumor growth (day 14). The impact of NAC-NIO on the tumor treatment was evaluated by measuring tumor size progress, comet assay, oxidative stress parameters (GSH, nitric oxide, MDA), western blot analysis, and histopathological investigation of tissues. NAC-NIO showed 72 ± 3% encapsulation efficiency and zeta potential - 5.95 mV with spherical shape. It was found that oral administration of NAC-NIO in a dose of 50 mg/kg provided significant protection against tumor cells. Our formulation decreases DNA injury significantly (P < 0.05). It was noticed that NAC-NIO can increase oxidative stress levels in tumor tissue. On the other hand, the caspase 3 and caspase 9 gene expression were upregulated significantly (P < 0.001) in mice administrated NAC-NIO compared with all other groups. Histological studies confirmed the protective effect of NAC-NIO against tumor especially for treatment during tumor growth protocol. The results suggested that oral delivery of NAC-NIO formulation improved antioxidant effect.

Nanocrocin Protective Effects on Paraquat-Induced Oxidative Stress in the MRC-5 Cell Line

Paraquat (PQ) herbicide poisoning is a severe medical problem in developing countries without suitable therapy. This study aimed to investigate the effects of crocin (CCN) and nano crocin (NCCN) on PQ -induced toxicity in the MRC-5 cell line. The results showed that the particle size of NCCN was 140.3 ± 18.0 nm, and the zeta potential of the optimal crocin-loaded niosomes was 23.4 ± 2.8 mV. The NCCN was more effective than CCN in the inhibition of PQ-induced toxicity. Treatment of the MRC-5 cells leads to a decrease in ROS and an increase in SOD, CAT, GPX, and TAC levels in PQ-CCN and PQ-NCCN groups compared with the PQ group. These changes tended to be positively associated with the NCCN compared to CCN. Overall, NCCN was more effective than crocin in treating PQ-induced toxicity in vitro and deserved further preclinical consideration.

Recent Trends in Nanocarrier-Based Drug Delivery System for Prostate Cancer

Prostate cancer remains a significant global health concern, requiring innovative approaches for improved therapeutic outcomes. In recent years, nanoparticle-based drug delivery systems have emerged as promising strategies to address the limitations of conventional cancer chemotherapy. The key trends include utilizing nanoparticles for enhancing drug delivery to prostate cancer cells. Nanoparticles have some advantages such as improved drug solubility, prolonged circulation time, and targeted delivery of drugs. Encapsulation of chemotherapeutic agents within nanoparticles allows for controlled release kinetics, reducing systemic toxicity while maintaining therapeutic efficacy. Additionally, site-specific accumulation within the prostate tumor microenvironment is made possible by the functionalization of nanocarrier with targeted ligands, improving therapeutic effectiveness. This article highlights the basics of prostate cancer, statistics of prostate cancer, mechanism of multidrug resistance, targeting approach, and different types of nanocarrier used for the treatment of prostate cancer. It also includes the applications of nanocarriers for the treatment of prostate cancer and clinical trial studies to validate the safety and efficacy of the innovative drug delivery systems. The article focused on developing nanocarrier-based drug delivery systems, with the goal of translating these advancements into clinical applications in the future.

Niosomes: A Smart Drug Delivery System for Brain Targeting

Niosomes are lipid-based nanovesicles that have the potential to act as drug-delivery vehicles for a variety of agents. They are effective drug delivery systems for both ASOs and AAV vectors, with advantages such as improved stability, bioavailability, and targeted administration. In the context of brain-targeted drug delivery, niosomes have been investigated as a drug delivery system for brain targeting, but more research is needed to optimize their formulation to improve their stability and release profile and address the challenges of scale-up and commercialization. Despite these challenges, several applications of niosomes have demonstrated the potential of novel nanocarriers for targeted drug delivery to the brain. This review briefly overviews the current use of niosomes in treating brain disorders and diseases.

Anti-oxidative properties of nanocrocin in Zearalenone induced toxicity on Hek293 cell; The novel formulation and cellular assessment

BACKGROUND

Zearalenone (ZEA) is a mycotoxin produced by fungi and induces cytotoxicity by the generation of reactive oxygen species. The aim of this study was to evaluate and compare the nephroprotective effects of crocin and nano-crocin against ZEA-induced toxicity in HEK293 cell line via modulation of oxidative stress and special formulation to make nano-crocin.

METHOD

Nano-crocin physicochemical properties, such as size, load, appearance, and drug release profile were determined. Also, the viability of intoxicated HEK293 cells was evaluated by MTT assay. Furthermore, lactate dehydrogenase lipid Peroxidation (LPO), and oxidative stress biomarkers were measured.

RESULT

The best nano-crocin formulation with superior entrapment effectiveness (54.66 ± 6.02), more significant drug loading (1.89 ± 0.01), better zeta potential (-23.4 ± 2.844), and smaller particle size (140.3 ± 18.0 nm) was chosen. This study showed that treatment with crocin and nano-crocin in ZEA-induced cells, significantly decreased LDH and LPO levels and increased superoxide dismutase (SOD), catalase (CAT) activities, and total antioxidant capacity (TAC) levels compared to the control group. Moreover, nano-crocin had a more curative effect against oxidative stress than crocin.

CONCLUSION

Niosomal structure of crocin, when administered with the special formulation, may be more beneficial in reducing ZEA-induced in vitro toxicity than conventional crocin.

Comprehensive Review on Applications of Surfactants in Vaccine Formulation, Therapeutic and Cosmetic Pharmacy and Prevention of Pulmonary Failure due to COVID-19

Our world is under serious threat of environmental degradation, climate change and in association with this the out breaks of diseases as pandemics. The devastating impact of the very recent COVID-19, The sharp increase in cases of Cancer, Pulmonary failure, Heart health has triggered questions for the sustainable development of pharmaceutical and medical sciences. In the search of inclusive and effective strategies to meet today’s demand, improvised methodologies and alternative green chemical, bio-based precursors are being introduced by scientists around the globe. In this extensive review we have presented the potentiality and Realtime applications of both synthetic and bio-based surfactants in bio-medical and pharmaceutical fields. For their excellent unique amphoteric nature and ability to solubilise in both organic and inorganic drugs, surfactants are one of the most potential candidates for bio-medicinal fields such as dermatology, drug delivery, anticancer treatment, surfactant therapy, vaccine formulation, personal hygiene care and many more. The self-assembly property of surfactants is a very powerful function for drug delivery systems that increases the bio-availability of the poorly aqueous soluble pharmaceutical products by influencing their solubility. Over the decades many researchers have reported the antimicrobial, anti-adhesive, antibiofilm, anti-inflammatory, antioxidant activities of surfactants regarding its utility in medicinal purposes. In some reports surfactants are found to have spermicidal and laxative activity too. This comprehensive report is targeted to enlighten the versatile applications of Surfactants in drug delivery, vaccine formulation, Cancer Treatment, Therapeutic and cosmetic Pharmaceutical Sciences and prevention of pulmonary failure due to COVID-19.

Novel Gels: An Emerging Approach for Delivering of Therapeutic Molecules and Recent Trends

Gels are semisolid, homogeneous systems with continuous or discrete therapeutic molecules in a suitable lipophilic or hydrophilic three-dimensional network base. Innovative gel systems possess multipurpose applications in cosmetics, food, pharmaceuticals, biotechnology, and so forth. Formulating a gel-based delivery system is simple and the delivery system enables the release of loaded therapeutic molecules. Furthermore, it facilitates the delivery of molecules via various routes as these gel-based systems offer proximal surface contact between a loaded therapeutic molecule and an absorption site. In the past decade, researchers have potentially explored and established a significant understanding of gel-based delivery systems for drug delivery. Subsequently, they have enabled the prospects of developing novel gel-based systems that illicit drug release by specific biological or external stimuli, such as temperature, pH, enzymes, ultrasound, antigens, etc. These systems are considered smart gels for their broad applications. This review reflects the significant role of advanced gel-based delivery systems for various therapeutic benefits. This detailed discussion is focused on strategies for the formulation of different novel gel-based systems, as well as it highlights the current research trends of these systems and patented technologies.

Hepatoprotective effect of N-acetylcystein loaded niosomes on liver function in paraquat-induced acute poisoning

Paraquat (PQ) is widely used as a herbicide around the world. PQ intoxication causes liver disease mainly in mammals. N-acetyl cysteine (NAC) is a medication that has positive effects in reducing the liver intoxication caused by PQ. Here, after formulating a NAC noisome nanoparticle (NACNP), we compared the niosomes and NAC on liver toxicity caused by PQ. Thirty male rats were divided into 5 groups and were treated intraperitoneally with PQ and NAC and NACNP for 24 h. PQ group received 35 mg/kg/day of PQ, while NAC and NACNP groups were administered with 25 mg/kg/day of NAC and NACNP, respectively. In addition, 6 rats receiving saline solution were considered as control group. Serum and liver tissue samples were collected from all rats. Alanine (AST) and aspartate (ALT) aminotransferase levels, and oxidative stress biomarkers including total antioxidant capacity (TAC), lipid peroxidation (LPO), and total thiol groups (TTG) levels were determined. Histological samples were also analyzed using hematoxylin and eosin staining slides. PQ administration resulted in hepatic injury as evidenced by increases in serum AST and ALT levels (p < .001). NACNP decreased LPO, TAC, and TTG levels compered to PQ group in liver tissue. Treatment of animals with NACNP was significantly more effective than free NAC in reducing PQ-induced hepatotoxicity (p < .05). Histological evaluation showed that PQ caused tissue inflammation, which was reduced by NAC treatment. This reduction was stronger for NACNP. Given these results, the use of NACNP, compared to NAC, was more protective against the development of the PQ-induced liver toxicity.

Niosomal Nanocarriers for Enhanced Skin Delivery of Quercetin with Functions of Anti-Tyrosinase and Antioxidant

This study aimed to screen an effective flavonoid with promising whitening and antioxidant capacities, and design flavonoid-loaded niosomes to improve its solubility, stability, and penetration. In vitro anti-tyrosinase and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging experiments were conducted to investigate the whitening and antioxidant capacities of several flavonoids, including quercetin, morin, festin, myricetin, rutin, and breviscapine. The conductivity, viscosity, and particle size of Span60-RH40-based formulation of nonionic surfactant vesicles (niosomes) with different mass ratios were studied to determine the most appropriate formulation. Drug-loaded niosomes were characterized for size, zeta potential, morphology, and entrapment efficiency. The photostability, solubility, release behavior, ex vivo drug penetration, and skin retention were also studied. The results showed that quercetin has considerable whitening and antioxidant capacities and Span60-RH40 at a mass ratio of 9:11 forms spherical or oval niosomes of 97.6 ± 3.1 nm with a zeta potential range of 31.1 ± 0.9 mV, and drug entrapment efficiency as high as 87.3 ± 1.6%. Niosomes remarkably improved the solubility and photostability of quercetin. Furthermore, compared to quercetin solution, quercetin-niosomes had the advantages of sustained release and improved transdermal penetration, with skin retention 2.95 times higher than quercetin solution.

Advances of Non-Ionic Surfactant Vesicles (Niosomes) and Their Application in Drug Delivery

Non-Ionic surfactant based vesicles, also known as niosomes, have attracted much attention in pharmaceutical fields due to their excellent behavior in encapsulating both hydrophilic and hydrophobic agents. In recent years, it has been discovered that these vesicles can improve the bioavailability of drugs, and may function as a new strategy for delivering several typical of therapeutic agents, such as chemical drugs, protein drugs and gene materials with low toxicity and desired targeting efficiency. Compared with liposomes, niosomes are much more stable during the formulation process and storage. The required pharmacokinetic properties can be achieved by optimizing components or by surface modification. This novel delivery system is also easy to prepare and scale up with low production costs. In this paper, we summarize the structure, components, formulation methods, quality control of niosome and its applications in chemical drugs, protein drugs and gene delivery.

Enhancement of Dissolution and Skin Permeability of Pentazocine by Proniosomes and Niosomal Gel

Proniosomes (PN) are the dry water-soluble carrier systems that may enhance the oral bioavailability, stability, and topical permeability of therapeutic agents. The low solubility and low oral bioavailability due to extensive first pass metabolism make Pentazocine as an ideal candidate for oral and topical sustained release delivery. The present study was aimed to formulate the PNs by quick slurry method that are converted to niosomes (liquid dispersion) by hydration, and subsequently formulated to semisolid niosomal gel. The PNs were found in spherical shape in the SEM and stable in the physicochemical and thermal analysis (FTIR, TGA, and XRD). The quick slurry method produced high recovery (> 80% yield) and better flow properties (θ = 28.1-37.4°). After hydration, the niosomes exhibited desirable entrapment efficiency (44.45-76.23%), size (4.98-21.3 μm), and zeta potential (- 9.81 to - 21.53 mV). The in vitro drug release (T_100%) was extended to more than three half-lives (2-4 h) and showed good fit to Fickian diffusion indicated by Korsmeyer-Peppas model (n = 0.136-0.365 and R² = 0.9747-0.9954). The permeation of niosomal gel was significantly enhanced across rabbit skin compared to the pure drug-derived gel. Therefore, the PNs are found promising candidates for oral as dissolution enhancement and sustained release for oral and topical delivery of pentazocine for the management of cancer pain.

Enhancing the Therapeutic Efficacy of Tamoxifen Citrate Loaded Span-Based Nano-Vesicles on Human Breast Adenocarcinoma Cells

Serious adverse effects and low selectivity to cancer cells are the main obstacles of long term therapy with Tamoxifen (Tmx). This study aimed to develop Tmx-loaded span-based nano-vesicles for delivery to malignant tissues with maximum efficacy. The effect of three variables on vesicle size (Y₁), zeta potential (Y₂), entrapment efficiency (Y₃) and the cumulative percent release after 24 h (Y₄) were optimized using Box-Behnken design. The optimized formula was prepared and tested for its stability in different storage conditions. The observed values for the optimized formula were 310.2 nm, - 42.09 mV, 75.45 and 71.70% for Y₁, Y₂, Y₃, and Y₄, respectively. The examination using electron microscopy confirmed the formation of rounded vesicles with distinctive bilayer structure. Moreover, the cytotoxic activity of the optimized formula on both breast cancer cells (MCF-7) and normal cells (BHK) showed enhanced selectivity (9.4 folds) on cancerous cells with IC₅₀ values 4.7 ± 1.5 and 44.3 ± 1.3 μg/ml on cancer and normal cells, respectively. While, free Tmx exhibited lower selectivity (2.5 folds) than optimized nano-vesicles on cancer cells with IC₅₀ values of 9.0 ± 1.1 μg/ml and 22.5 ± 5.3 μg/ml on MCF-7 and BHK cells, respectively. The promising prepared vesicular system, with greater efficacy and selectivity, provides a marvelous tool to overcome breast cancer treatment challenges.

Establishing Structure Property Relationship in Drug Partitioning into and Release from Niosomes: Physical Chemistry Insights with Anti-Inflammatory Drugs

Understanding the physical chemistry underlying interactions of drugs with delivery formulations is extremely important in devising effective drug delivery systems. The partitioning and release kinetics of diclofenac sodium and naproxen from Brij 30 and Triton X-100 niosomal formulations have been addressed based on structural characterization, partitioning energetics, and release kinetics, thus establishing a relationship between structures and observed properties. Both the drugs partition in nonpolar regions of TX-100 niosomes via stacking of aromatic rings. The combined effects of interactions of the drugs with polar head groups and the rigidity of the niosome vesicles determine entry and partitioning of drugs into niosomes. The observed slower rate of release of the drugs from the drug encapsulated niosomes of TX-100 than those of Brij 30, suggest stable complexation of drugs in the nonpolar interior of the former. No release of drugs from the niosomes was observed until 24 h even upon varying pH conditions without SDS. However, SDS in drug loaded niosomes led to release of drugs in as early as 6 h. The sustained pattern of in vitro release kinetics of the drugs thus observed from our niosomal preparations suggest these vesicular systems to be promising for pharamaceutical applications as potential drug delivery vehicles.

Development of a Drug Delivery System Based on Chitosan Nanoparticles for Oral Administration of Interferon-α

Despite the good clinical efficacy of interferon-alpha (IFNα) to treat some types of cancer and viral infections, this biological drug is underused given its severe adverse effects and high dosing parenteral regimens. Aiming to achieve a breakthrough in therapy with IFNα, this work reports for the first time on the design and full characterization of a novel nanomedicine of IFNα-2b-loaded chitosan nanoparticles (IFN-CT NPs) for oral delivery. IFN-CT NPs produced by ionotropic gelation, encapsulating approximately 100% of the drug, showed a size of 36 ± 8 nm, zeta potential of +30 mV (dynamic light scattering), and spherical morphology (transmission electron microscopy). The antiviral activity of IFN-CT NPs in vitro was comparable to that of commercial IFNα. Remarkably, both treatments stimulated the expression of IFN response genes to a similar extent in both noninfected and infected cells with Human Lymphotropic-T Virus type 1. Finally, oral administration of IFN-CT NPs (0.3 MIU) to CF1 mice showed detectable levels of IFNα in plasma after 1 h, whereas no IFNα was detected with a commercial formulation. These results are encouraging and open a new avenue for the administration of this biological drug in a minimally invasive, safer, and more patient-compliant way.

Non-Ionic Surfactant Vesicles (Niosomes) as New Drug Delivery Systems

Lipid vesicular systems composed of hydrated amphihiles with or without bilayer inducing agents such as cholesterol. On the basis of used amphiphilic molecule different nomenclature are used as liposomes, ufasomes and niosomes. Nonionic surfactants with mono-, di- or trialkyl chains form niosomes which are lipid vesicles with more chemical stability in comparison with phospholipids of liposomes. Both hydrophobic and hydrophilic chemicals can be encapsulated in niosomes as a new drug delivery system. This drug carrier system could have administered via injection, oral, pulmonary, vaginal, rectal, ophthalmic, nasal or transdermal routes with penetration enhancing potential. This chapter presents a detailed explain about niosome forming components, methods of preparation and routes of administration. Many examples for drug delivery potential of niosomes are also available in this review. Vaccine adjuvant and genetic substances vector capabilities are not given here.

Non-Ionic Surfactant Vesicles (Niosomes) as New Drug Delivery Systems

Lipid vesicular systems composed of hydrated amphihiles with or without bilayer inducing agents such as cholesterol. On the basis of used amphiphilic molecule different nomenclature are used as liposomes, ufasomes and niosomes. Nonionic surfactants with mono-, di- or trialkyl chains form niosomes which are lipid vesicles with more chemical stability in comparison with phospholipids of liposomes. Both hydrophobic and hydrophilic chemicals can be encapsulated in niosomes as a new drug delivery system. This drug carrier system could have administered via injection, oral, pulmonary, vaginal, rectal, ophthalmic, nasal or transdermal routes with penetration enhancing potential. This chapter presents a detailed explain about niosome forming components, methods of preparation and routes of administration. Many examples for drug delivery potential of niosomes are also available in this review. Vaccine adjuvant and genetic substances vector capabilities are not given here.

A review on the strategies for oral delivery of proteins and peptides and their clinical perspectives

In the modern world, a number of therapeutic proteins such as vaccines, antigens, and hormones are being developed utilizing different sophisticated biotechnological techniques like recombinant DNA technology and protein purification. However, the major glitches in the optimal utilization of therapeutic proteins and peptides by the oral route are their extensive hepatic first-pass metabolism, degradation in the gastrointestinal tract (presence of enzymes and pH-dependent factors), large molecular size and poor permeation. These problems can be overcome by adopting techniques such as chemical transformation of protein structures, enzyme inhibitors, mucoadhesive polymers and permeation enhancers. Being invasive, parenteral route is inconvenient for the administration of protein and peptides, several research endeavors have been undertaken to formulate a better delivery system for proteins and peptides with major emphasis on non-invasive routes such as oral, transdermal, vaginal, rectal, pulmonary and intrauterine. This review article emphasizes on the recent advancements made in the delivery of protein and peptides by a non-invasive (peroral) route into the body.

Niosomes from 80s to present: the state of the art

Efficient and safe drug delivery has always been a challenge in medicine. The use of nanotechnology, such as the development of nanocarriers for drug delivery, has received great attention owing to the potential that nanocarriers can theoretically act as "magic bullets" and selectively target affected organs and cells while sparing normal tissues. During the last decades the formulation of surfactant vesicles, as a tool to improve drug delivery, brought an ever increasing interest among the scientists working in the area of drug delivery systems. Niosomes are self assembled vesicular nanocarriers obtained by hydration of synthetic surfactants and appropriate amounts of cholesterol or other amphiphilic molecules. Just like liposomes, niosomes can be unilamellar or multilamellar, are suitable as carriers of both hydrophilic and lipophilic drugs and are able to deliver drugs to the target site. Furthermore, niosomal vesicles, that are usually non-toxic, require less production costs and are stable over a longer period of time in different conditions, so overcoming some drawbacks of liposomes. The niosome properties are specifically dictated by size, shape, and surface chemistry which are able to modify the drug's intrinsic pharmacokinetics and eventual drug targeting to the areas of pathology. This up-to-date review deals with composition, preparation, characterization/evaluation, advantages, disadvantages and application of niosomes.

Niosomes in sustained and targeted drug delivery: some recent advances

Niosomes represent an emerging class of novel vesicular systems. They are composed of nonionic surfactants which are biodegradable and relatively nontoxic. They were developed as stable and inexpensive alternatives to liposomes. Since their early introduction to cosmetic industry their role has diversified to other application areas. They are now being ardently explored as potential carriers for sustained and targeted drug delivery. In addition to conventional, oral, and parenteral routes, they are amenable to be delivered by ocular, transdermal, vaginal, and inhalation routes. Delivery of biotechnological products including vaccine delivery with niosomes is also an interesting and promising research area. The introduction of provesicular approach in the form of proniosomes has further increased the relevance of these systems. More concerted research efforts, however, are still required to realize the full potential of these novel systems. This review considers the current status and explores the potential of niosomes in drug delivery with special attention to their role in drug targeting. Their methods of preparation, formulation aspects, advantages, limitations, and applications are also discussed.

Niosomes with Sorbitan Monoester as a Carrier for Vaginal Delivery of Insulin: Studies in Rats

To prepare and investigate the potential of the niosomes vaginal delivery system for systemic treatment of insulin is the goal of this study. Two kinds of vesicles with Span 40 and Span 60 were prepared by lipid phase evaporation methods with sonication. The niosomal entrapment efficiency was determined by column chromatography. The particle size and morphology of the vesicles also were evaluated. The results showed optimized niosomes prepared in this study had niosomal entrapment efficiency 26.68 +/- 1.41% for Span 40 and 28.82 +/- 1.35% for Span 60, respectively. The particle sizes of Span 40 niosomes and Span 60 niosomes were 242.5 +/- 20.5 nm and 259.7 +/- 33.8 nm, respectively. There were no significant differences in appearance between the two types of vesicles. The hypoglycemic effects, and insulin concentrations after vaginal administration of insulin vesicles to rats were investigated. Compared with subcutaneous administration of insulin solution, the relative pharmacological bioavailability and the relative bioavailability of vaginal administration of insulin vesicles were determined. Compared with subcutaneous administration of insulin solution, the relative pharmacological bioavailability and the relative bioavailability of insulin-Span 60 vesicles group were 8.43% and 9.61%, and insulin-Span 40 niosomes were 9.11% and 10.03% (p > 0.05). Span 60 and Span 40 niosomes were both higher than blank Span 40, Span 60 vesicles, and free insulin physical mixture groups (p < 0.05). The results indicates insulin-Span 60, Span 40 niosomes had an enhancing effect on vaginal delivery of insulin. Although the factors controlling the process for penetration of a portion of vaginally administrated niosomes into bloodstream from vaginal tract is still not fully understood, our results demonstrated that after encapsulation in niosomes of definite type, insulin became an active and efficiently therapeutic agent when administrated vaginally and might be a good carrier for vaginal delivery of protein drugs.

In vitro study of polyoxyethylene alkyl ether niosomes for delivery of insulin

In this study, niosomes of polyoxyethylene alkyl ethers (Brij) were prepared for encapsulation of insulin by film hydration method. Without cholesterol, brij 35 and brij 58 did not form niosomes, apparently because of relatively large polar head groups in comparison with their alkyl chains. The size of vesicles depended on the cholesterol content, charge incorporation or hydrophilicity of surfactants. Entrapment of insulin in bilayer structure of niosomes protected it against proteolytic activity of alpha-chymotrypsin, trypsin and pepsin in vitro. The maximum protection activity was seen in brij 92/cholesterol (7:3 molar ratios) in which only 26.3+/-3.98% of entrapped insulin was released during 24h in simulated intestinal fluid (SIF). The kinetic of drug release for most formulations could be best described by Baker and Lonsdale equation indicating diffusion based delivery mechanism. These results indicate that niosomes could be developed as sustained release oral dosage forms for delivery of peptides and proteins such as insulin.

In vitro enzymatic stability of dendritic peptides

PEGylated polyamidoamine (PAMAM) dendrimers as drug carriers have been a topic of interest because of their biomedically favorable features, including minimal toxicity, reduced immunogenicity, and excellent solubility in aqueous and most organic solutions. A PEG shell on dendrimer surface may provide steric hindrance, known as stealth properties of PEG, to stabilize drug molecules to be delivered. In this article, the effects of PEG and coupling sequence of drug, PEG, and dendrimer in modulating the stability of delivered drug molecules were evaluated. N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide was chosen as a model peptide. Dendritic peptides, that is, peptide-dendrimer, peptide-PAMAM-PEG, and peptide-PEG-dendrimer, were constructed based on Starbursttrade mark G3.0 PAMAM dendrimer and characterized by (1)H-NMR spectroscopy. Hydrolysis of dendritic peptides was catalyzed by alpha-chymotrypsin in pH 7.4 PBS buffer containing 5% DMF (v/v) at room temperature. The enzymatic stability of dendritic peptides was peptide-PAMAM-PEG > peptide-PAMAM > free peptide > peptide-PEG-PAMAM. The ratio of PEG/peptide could be reduced for increasing peptide loading while maintaining the delivered peptides' relatively high enzymatic stability. The quantitative analysis of dendritic peptide/enzyme interactions provided the understandings of the molecular structure/stability relationships of dendrimer/drug for the design of an optimal PEGylated dendrimer-based drug-delivery system.

Development and physical characterization of sorbitan monoester niosomes for insulin oral delivery

Niosomes of sorbitan monoesters (Span 20, 40, 60, and 80) were prepared using the film hydration method without sonication. Unlike the other surfactants, Span 80 did not form niosomes in the absence of a sufficient amount of cholesterol. The size of vesicles depended on the cholesterol molar ratio or charge incorporation. The amount of insulin released in simulated intestinal fluid from Span 40 and 60 was lower than Span 20 and 80 vesicles. Vesicles containing Span 60 showed the highest protection of insulin against proteolytic enzymes and good stability in the presence of sodium desoxycholate and storage temperatures.

In vitro evaluation of pH-sensitive polymer/niosome complexes

Large unilamellar niosome and control liposome vesicles were rendered pH-sensitive by complexation with a hydrophobically modified pH-responsive copolymer of N-isopropylacrylamide, N-glycidylacrylamide, and N-octadecylacrylamide at a copolymer/lipid mass ratio of 0.3. The vesicles were characterized and tested for their stability and pH-sensitivity in buffer and human serum. Their in vitro cytotoxicity was evaluated as well as their ability to mediate cytoplasmic delivery of encapsulated fluorescent probe using J774 murine macrophage-like cells. At pH 7.2, vesicles were found to be stable over 90 days at 4 degrees C. At 37 degrees C, the polymer destabilized the vesicles under weakly acidic conditions. However, niosomes but not liposomes were partly destabilized in human serum at 37 degrees C. Premature leakage of niosomal contents in serum was attributed to the polymer collapse which is favored in the presence of multivalent cations. On the cellular level, niosomes were cytotoxic above 0.075 mM while no appreciable decrease in cell viability was shown for the liposomes and copolymer alone at short incubation times (< 2 days). Finally, only liposomes and not niosomes were able to release their contents in the cytoplasm after internalization by phagocytosis.

Antimetastatic efficacy of niosomal pentoxifylline and its combination with activated macrophages in murine B16F10 melanoma model

The aims of the present study were a) to enhance the effectiveness of antimetastatic agent, Pentoxifylline (PTX) by encapsulation in niosomes and b) to investigate the anticancer activity by combination therapy involving activated macrophages and PTX solution/PTX niosomes. Niosomes were prepared by lipid film hydration method. Particle size distribution revealed bimodal distribution with median vesicle size of 462 nm. The entrapment efficacy of PTX niosomes was found to be 9.64%. A cumulative release of 82.43% from niosomal suspension was observed at the end of 21 hours. Intravenous administration of niosomal PTX (6 mg/kg and 10 mg/kg) resulted in significant reduction in lung nodules in an experimental metastatic B16F10 model suggesting accumulation of PTX in a distant target organ-lung. Light microscopic observations of histologic sections showed a decrease in number of tumor islands in the lung. Macrophages activated by intraperitoneal injection of Iscove's Modified Dulbecco's Medium (IMDM) containing 20% fetal calf serum (FCS) followed by in vitro incubation with muramyl dipeptide (MDP) were more effective in controlling tumor spread than those activated by FCS alone. Combination therapy of activated macrophages and PTX solution/niosomal PTX showed no additive or synergistic effect in controlling tumor spread. Carbon clearance studies revealed that PTX inhibits the phagocytic ability of activated macrophages, thereby resulting in the failure of combination therapy.

Stable reversed vesicles in oil: characterization studies and encapsulation of model compounds

The formation of reversed sucrose ester vesicles in silicon oil and mixtures of silicon oil and isopropyl palmitate was studied. The vesicles were characterized by polarized light microscopy, freeze-fracture electron microscopy, and differential scanning calorimetry. Furthermore the ability to encapsulate p-aminobenzoic acid and cholesterol in such vesicles was studied. The vesicles were multilamellar and had sizes up to several micrometers. The vesicles agglomerated but did not show fusion for at least 2 years when stored at room temperature in glass vials. The encapsulation efficiency of both p-aminobenzoic acid and cholesterol strongly depended on the oil phase in which the vesicles were prepared. Reversed sucrose ester vesicles in silicon oil encapsulated nearly 100% of the amount of p-aminobenzoic acid or cholesterol present in the dispersion. These compounds were encapsulated in different compartments of the vesicles. Reversed sucrose ester vesicles offer new perspectives regarding the development of novel pharmaceutical dosage forms.

Nonionic surfactant vesicles (niosomes) of cytarabine hydrochloride for effective treatment of leukemias: encapsulation, storage, and in vitro release

Niosome vesicles of cytarabine hydrochloride were prepared by a lipid hydration method that excluded dicetylphosphate. The sizes of the vesicles obtained ranged from 600 to 1000 nm, with the objective of producing more blood levels in vivo. The study of the release of drug from niosomes exhibited a prolonged release profile as studied over a period of 16 hr. The drug entrapment efficiency was about 80% with Tween 80, Span 60 and Tween 20; for Span 80, it was 67.5%. The physical stability profile of vesicular suspension was good as studied over a period of 4 weeks.

Current concepts in intestinal peptide absorption

Today there is considerable interest in oral peptide delivery. However, oral administration of peptides is limited by a low bioavailability and a high variability in plasma levels. A review is given of the literature describing the major barriers in peptide absorption, the basic mechanisms of intestinal peptide transport, the experimental models and the pharmaceutical approaches currently used in the investigation of peptide and protein absorption processes.