Dispersion and stabilization of cochleate nanoparticles

A novel Ca2+ double cone vector system to treat compromised skin

BACKGROUND

Stressed, damaged or very aged skin is predominantly characterized by a malfunctioning skin barrier. Underlying skin barrier malfunction is a reduced or defective calcium gradient in the epidermis. Consequently, replenishing the compromised skin's calcium stores with topical calcium could be a potential therapeutic approach.

METHODS

We investigated the effect of our novel Ca2+ double cone vector system on improving the differentiation and barrier function of reconstructed human epidermis (RHE), cultured at low basal calcium (0.3 mM) to represent very aged skin. Furthermore, in a randomized placebo-controlled clinical study the skin barrier of 20 healthy volunteers was challenged with 2% sodium lauryl sulphate (SLS) for 24 h under occlusion, following and/or prior to treatment with a gel containing 2% of our calcium vector system.

RESULTS

Culture in reduced basal calcium conditions (0.3 mM) strongly impeded the formation of a dense stratified epidermis. The apical treatment with 1.1 mM CaCl2 was not able to restore a functional differentiation. Treatment with 0.1% of the Ca2+ delivery system rescued the differentiation process and resulted in a normal stratified epidermis. Clinically, application of the Ca2+ vector system prior to and following SLS stress prevented increases in skin irritation and transepidermal water loss (TEWL) compared to placebo controls. Importantly, the treatment also significantly accelerated the recovery time following SLS stress.

CONCLUSION

With our novel Ca2+ vector system, we highlight the delivery of bioavailable Ca2+ ions into the skin as a new and successful approach to treat a damaged barrier present in stressed, aged or atopic skin.

Nanoliposomes Embedded Nanocochleates for Codelivery of Artemether and Lumefantrine: An In Vitro and In Vivo Study

Antimalarial drugs are being encapsulated in nanotechnology-based carriers because there are not enough new treatment options and people are becoming more resistant to the ones that are already available. This approach uses two or more biochemical targets of malarial parasites. The codelivery of artemether and lumefantrine (AL) combines the synergistic effect of artemether for an early onset of action followed by the prolonged effect of lumefantrine. The bioavailability of artemether and lumefantrine is low due to their low solubility. Thus, an alternative lipidic formulation, namely nanocochleate, was developed for the selected drugs by adding calcium ions into preformed nanoliposomes (AL-loaded liposomes). Using phospholipon 90H and cholesterol, a thin-film hydration method produced drug-loaded liposomes. The synthesized AL-loaded liposomes were further incorporated into nanocochleates. The formulations were evaluated for in vitro and in vivo parameters. Nanocochleates had a particle size of 200.7 nm, a zeta potential of -9.4 mV, and an entrapment efficiency of 73.12% ± 1.82% and 61.46% ± 0.78%, respectively, for artemether and lumefantrine. Whereas liposomes had a particle size of 210 nm and an entrapment efficiency of 67.34% ± 1.52% and 53.24% ± 0.78%, respectively, for artemether and lumefantrine. An X-ray diffraction study confirmed the amorphous state of artemether and lumefantrine in liposomes and nanocochleate. Nanocochleate showed a controlled release profile for loaded drugs. When compared with free drugs, nanocochleate showed low tissue distribution and a 20-fold increase in bioavailability in rats. Thus, nanocochleate offers an interesting alternative to an existing dosage form for the treatment of malaria.

Feasibility of the preparation of cochleate suspensions from naturally derived phosphatidylserines

Introduction

Cochleates are cylindrical particles composed of dehydrated phospholipid bilayers. They are typically prepared by addition of calcium ions to vesicles composed of negatively charged phospholipids such as phosphatidylserines (PS). Due to their high physical and chemical stability, they provide an interesting alternative over other lipid-based drug formulations for example to improve oral bioavailability or to obtain a parenteral sustained-release formulation.

Methods

In the present study, the feasibility to prepare cochleate suspensions from soy lecithin-derived phosphatidylserines (SPS) was investigated and compared to the "gold standard" dioleoyl-phosphatidylserine (DOPS) cochleates. The SPS lipids covered a large range of purities between 53 and >96% and computer-controlled mixing was evaluated for the preparation of the cochleate suspensions. Electron microscopic investigations were combined with small-angle x-ray diffraction (SAXD) and Laurdan generalized polarization (GP) analysis to characterize particle structure and lipid organization.

Results

Despite some differences in particle morphology, cochleate suspensions with similar internal lipid structure as DOPS cochleates could be prepared from SPS with high headgroup purity (≥96%). Suspensions prepared from SPS with lower purity still revealed a remarkably high degree of lipid dehydration and well-organized lamellar structure. However, the particle shape was less defined, and the typical cochleate cylinders could only be detected in suspensions prepared with higher amount of calcium ions. Finally, the study proves the feasibility to prepare suspensions of cochleates or cochleate-like particles directly from a calcium salt of soy-PS by dialysis.

Pharmacokinetics, biodistribution, and activity of Amphotericin B-loaded nanocochleates on the Leishmania donovani murine visceral leishmaniasis model

Amphotericin B (AmB) is an effective drug to treat visceral leishmaniasis but its use is limited by its poor oral bioavailability. This article describes the in-vivo evaluation of AmB-loaded, lipid-based cochleate systems designed for the oral route. Two different cochleate formulations were studied: one based on the synthetic phospholipid dioleoylphosphatidylserine (DOPS) and another optimized formulation based on a naturally occurring phosphatidylserine (Lipoid PSP70) that would render the formulation more affordable in developing countries. Their antiparasitic activity was evaluated in a mouse model of visceral leishmaniasis. Limited efficacy was observed for the DOPS-based cochleates after three doses of AmB at 1 mg/kg. The Lipoid PSP70-based cochleates were administered either as a buffered suspension or in enteric-coated capsules. AmB-loaded cochleates administered as a suspension at a high dose (3 × 20 mg/kg) exhibited significant antiparasitic activity while AmB-loaded cochleates in enteric-coated capsules at a lower dose (3 × 5 mg/kg) presented a slightly higher significant activity. A pharmacokinetic and biodistribution study in rats was performed with the Lipoid PSP70-based cochleates, with a single oral dose of 7.5 mg AmB/kg. Cochleates in both administration forms led to lower concentrations of Amphotericin B in the plasma than intravenous AmBisome®. However, more accumulation in the organs of interest (liver, spleen) was observed for both presentations of cochleates than for AmBisome® by the oral route. Therefore, cochleate formulations of AmB that could be produced at a cost accessible for developing countries show promise for the treatment of visceral leishmaniasis.

Cochleate drug delivery systems: An approach to their characterization

Cochleate systems formed from phospholipids have very useful properties as drug delivery systems with sustained release capabilities, which are able to improve bioavailability and efficacy, reduce toxicity and increase the shelf-life of encapsulated molecules. These nanometric or micrometric structures are usually obtained after interaction of negatively charged liposomes with a positively charged bridging agent. Many different methods are now available to prepare cochleates and there are also numerous techniques that can be used to characterize them, some of which can be easily applied while others require more sophisticated equipment or analysis. The present review describes the important features of this drug delivery system; including their structural properties and potential applications, as well as a brief account of methods for their preparation and an extensive description of the techniques used for their characterization. This information could guide formulators in their choice of methods of characterization that would be best suited to their needs in terms of time, precision and technological difficulty.

Cochleate formulations of Amphotericin b designed for oral administration using a naturally occurring phospholipid

The purpose of this work was to formulate the poor soluble antifungal and antiparasitic agent Amphotericin B (AmB) in cost-effective lipid-based formulations suitable for oral use in developing countries, overcoming the limitations of poor water solubility, nephrotoxicity and low oral bioavailability. The antifungal agent was formulated, at different molar proportions, in cochleate nanocarriers prepared using an accessible naturally occurring phospholipid rich in phosphatidylserine (Lipoid PSP70). These nanoassemblies were prepared by condensation of negatively charged phospholipid membrane vesicles with divalent cations (Ca²⁺). Small-angle X-ray scattering studies revealed the Ca²⁺-triggered condensation of loosely packed multilamellar vesicles into tightly packed bilayers of strongly dehydrated multilamellar organization characterized by narrow Bragg peaks. Transmission electron microscopy and quasi-elastic light scattering studies demonstrated the formation of nanosized particles. AmB drug loading was above 55% in all formulations. Circular dichroism demonstrated the prevalence of monomeric and complexed forms of AmB over toxic aggregates. The stability of AmB in gastric medium was improved by loading in cochleates and its release in gastrointestinal media was retarded. Confocal microscopy studies revealed the in-vitro interactions of Lipoid PSP70-based cochleates with Caco2 intestinal cell monolayers. The results suggest that the low-cost AmB-loaded cochleates may increase the therapeutic range of this drug.

Oral Nano Drug Delivery Systems for the Treatment of Type 2 Diabetes Mellitus: An Available Administration Strategy for Antidiabetic Phytocompounds

In view of the worldwide serious health threat of type 2 diabetes mellitus (T2DM), natural sources of chemotherapies have been corroborated as the promising alternatives, with the excellent antidiabetic activities, bio-safety, and more cost-effective properties. However, their clinical application is somewhat limited, because of the poor solubility, instability in the gastrointestinal tract (GIT), low bioavailability, and so on. Nowadays, to develop nanoscaled systems has become a prominent strategy to improve the drug delivery of phytochemicals. In this review, we primarily summarized the intervention mechanisms of phytocompounds against T2DM and presented the recent advances in various nanosystems of antidiabetic phytocompounds. Selected nanosystems were grouped depending on their classification and structures, including polymeric NPs, lipid-based nanosystems, vesicular systems, inorganic nanocarriers, and so on. Based on this review, the state-of-the-art nanosystems for phytocompounds in T2DM treatment have been presented, suggesting the preponderance and potential of nanotechnologies.

Novel osteoprotective nanocochleate formulation: A dual combination therapy-codelivery system against glucocorticoid induced osteoporosis

Phosphatidylserine nanocochleates (Nanocochs) are novel delivery systems that may play a prominent osteoprotective role with their cargo, vitamin D3 (Vit-D3), against osteoporosis. Therefore, this study was conducted to characterize a Nanococh containing vitamin D3 (Nanococh-D3) and investigate its potential role in improving GIO in a rat model. Roll-shaped Nanococh-D3 particles were obtained in a size range of 320 nm with a sustained release performance. Oral Nanococh-D3 significantly increased the bioavailability of Vit-D3, enhanced bone mechanical strength, and improved osteogenic biomarkers including B-ALP, osteocalcin, Ca, and OPG in GIO rats. This formulation markedly suppressed gene expression of RANK and RANKL in treated rats. Histomorphometric analysis showed significant repairs in bone tissues and TRAP staining indicated a significant decrease in osteoclasts using Nanococh-D3 in osteoporotic rats. Nanococh alone similar to Nanococh-D3 acted better than AL as a standard anti-osteoporotic drug in the improvement of bone strength. In conclusion, our results established the potential role of Nanococh-D3 against osteoporosis in rats.

Stable, Monodisperse, and Highly Cell-Permeating Nanocochleates from Natural Soy Lecithin Liposomes

(1) Background: Andrographolide (AN), the main diterpenoid constituent of Andrographis paniculata, has a wide spectrum of biological activities. The aim of this study was the development of nanocochleates (NCs) loaded with AN and based on phosphatidylserine (PS) or phosphatidylcholine (PC), cholesterol and calcium ions in order to overcome AN low water solubility, its instability under alkaline conditions and its rapid metabolism in the intestine. (2) Methods: The AN-loaded NCs (AN⁻NCs) were physically and chemically characterised. The in vitro gastrointestinal stability and biocompatibility of AN⁻NCs in J77A.1 macrophage and 3T3 fibroblasts cell lines were also investigated. Finally, the uptake of nanocarriers in macrophage cells was studied. (3) Results: AN⁻NCs obtained from PC nanoliposomes were suitable nanocarriers in terms of size and homogeneity. They had an extraordinary stability after lyophilisation without the use of lyoprotectants and after storage at room temperature. The encapsulation efficiency was 71%, while approximately 95% of AN was released in PBS after 24 h, with kinetics according to the Hixson⁻Crowell model. The in vitro gastrointestinal stability and safety of NCs, both in macrophages and 3T3 fibroblasts, were also assessed. Additionally, NCs had extraordinary uptake properties in macrophages. (4) Conclusions: NCs developed in this study could be suitable for both AN oral and parental administration, amplifying its therapeutic value.