A Density-Changing Centrifugation Method for Efficient Separation of Free Drugs from Drug-Loaded Particulate Delivery Systems

Assessment of In Vitro Release Testing Methods for Colloidal Drug Carriers: The Lack of Standardized Protocols

Although colloidal carriers have been in the pipeline for nearly four decades, standardized methods for testing their drug-release properties remain to be established in pharmacopeias. The in vitro assessment of drug release from these colloidal carriers is one of the most important parameters in the development and quality control of drug-loaded nano- and microcarriers. This lack of standardized protocols occurs due to the difficulties encountered in separating the released drug from the encapsulated one. This review aims to compare the most frequent types of release testing methods (i.e., membrane diffusion techniques, sample and separate methods and in situ detection techniques) in terms of the advantages and disadvantages of each one and of the key parameters that influence drug release in each case.

Pluronic F127 coating performance on PLGA nanoparticles: Enhanced flocculation and instability

Nanoparticles (NPs) can be incorporated into hydrogels to obtain multifunctional hybrid systems to meet the delivery needs of different drugs. However, the stability of NPs in hydrogels is rarely revealed. In this article, we tried to explore the underlying mechanism of an interesting phenomenon that poly(lactic-co-glycolic acid) (PLGA) nanoparticles (PNPs) could flocculate and deposit in Pluronic F127 (F127) hydrogels at 4 °C. The results showed that this flocculation was relevant to the type of emulsifier formulated in PNPs, the particle materials and the F127 concentration, but independent of PLGA polymer end groups. Exactly, PNPs containing polyvinyl alcohol (PVA) as the emulsifier flocculated in F127 solution with a concentration above 15 %. The flocculated PNPs possessed increased particle size, decreased zeta potential, reduced hydrophobicity and an obvious coating layer, and these characteristics could be restored almost to the original state after two washes of flocculated PNPs with water. Moreover, the flocculation had no impact on the long-term size stability and drug-loading capacity of PNPs, and F127-treated PNPs showed improved cellular uptake than untreated PNPs. These results provide the evidence that adsorption of high concentrations of F127 on the surface of PNPs/PVA may lead to flocculation, and the flocculation is reversible by simply washing the flocs with water. To the best of our knowledge, this is the first study to scientifically explore the stability of PNPs in F127 hydrogels, providing theoretical and experimental support for the rational design and further development of nanoparticle-hydrogel composite.

RK, R. AT, P. GM, S. P, John A. Bilosomes as a Potential Carrier to Enhance Cognitive Effects of Bacopa monnieri Extract on Oral Administration

The Indian system of medicine, Ayurveda employs Bacopa monnieri extract (BME) for memory enhancement. This study attempts to prepare and test a more potent formulation by incorporating BME in nanovesicles. BME-loaded liposomes and bilosomes (bile salt-stabilized liposomes) were formulated using soy phosphatidylcholine. Liposomes and bilosomes had homogeneous size distribution and an average size of 285.7 nm and 84 nm, respectively, with satisfactory zeta potential. Spherical multilamellar bilosomes and unilamellar liposomes were observed under transmission electron microscope (TEM), with BME entrapment efficiency of 85% and 45%, respectively. During a 72 h interval, bilosomes and liposomes released 78% and 65% of the loaded BME, exhibiting a biphasic release, following the Higuchi model diffusion. Both liposomes and bilosomes were stable in simulated gastric and intestinal fluids. When tested on dementia-induced Swiss albino mouse models using the Y-maze apparatus, the bilosome-treated group showed significant cognition enhancement activity than those treated with liposomal vesicles. The better pharmacological effect shown by bilosomes may be attributed to better bioavailability, possibly augmented by higher entrapment efficiency, and improved vesicle integrity afforded by bile salts. Likewise, bilosomes were more stable than liposomes in simulated gastric and intestinal fluids. Taken together, innovative formulation techniques hold substantial promise for enhancing the ethnopharmacological claims of BME.

Current hurdles to the translation of nanomedicines from bench to the clinic

The field of nanomedicine has significantly influenced research areas such as drug delivery, diagnostics, theranostics, and regenerative medicine; however, the further development of this field will face significant challenges at the regulatory level if related guidance remains unclear and unconsolidated. This review describes those features and pathways crucial to the clinical translation of nanomedicine and highlights considerations for early-stage product development. These include identifying those critical quality attributes of the drug product essential for activity and safety, appropriate analytical methods (physical, chemical, biological) for characterization, important process parameters, and adequate pre-clinical models. Additional concerns include the evaluation of batch-to-batch consistency and considerations regarding scaling up that will ensure a successful reproducible manufacturing process. Furthermore, we advise close collaboration with regulatory agencies from the early stages of development to assure an aligned position to accelerate the development of future nanomedicines.

Spotlight on the protein corona of liposomes

Although an established drug delivery platform, liposomes have not fulfilled their true potential. In the body, interactions of liposomes are mediated by the layer of plasma proteins adsorbed on the surface, the protein corona. The review aims to collect the data of the last decade on liposome protein corona, tracing the path from interactions of individual proteins to the effects mediated by the protein corona in vivo. It offers a classification of the approaches to exploitation of the protein corona-rather than elimination thereof-based on the bilayer composition-corona composition-molecular interactions-biological performance framework. The multitude of factors that affect each level of this relationship urge to the widest implementation of bioinformatics tools to predict the most effective liposome compositions relying on the data on protein corona. Supplementing the picture with new pieces of accurately reported experimental data will contribute to the accuracy and efficiency of the predictions. STATEMENT OF SIGNIFICANCE: The review focuses on liposomes as an established nanomedicine platform and analyzes the available data on how the protein corona formed on liposome surface in biological fluids affects performance of the liposomes. The review offers a rigorous account of existing literature and critical analysis of methodology currently applied to the assessment of liposome-plasma protein interactions. It introduces a classification of the approaches to exploitation of the protein corona and tailoring liposome carriers to advance the field of nanoparticulate drug delivery systems for the benefit of patients.

Is centrifugal ultrafiltration a robust method for determining encapsulation efficiency of pesticide nanoformulations?

Loading active ingredients on nanocarrier systems is becoming a common strategy for improving pesticide formulations. One of the most important properties of these nanoformulations is the proportion of pesticide associated with the nanocarriers (encapsulation efficiency, EE). EE is often determined by centrifugal ultrafiltration. However, the losses of active ingredient in the centrifugal ultrafiltration devices are typically not assessed, potentially leading to erroneous results. In this work, the losses of three pesticides (tebuconazole, terbuthylazine and chlorpyrifos) during centrifugal ultrafiltration have been systematically evaluated for nine different devices. Results suggest that centrifugal ultrafiltration is not suitable for determining the EE of compounds such as chlorpyrifos as 100% losses were observed on all the devices tested. Losses of tebuconazole and terbuthylazine were highly variable according to the type of membrane and the lowest losses were observed in the devices with hydrophilic regenerated cellulose membranes. Based on these results, we propose a correction factor and demonstrate its application to calculate the EE of two nanoformulations based on poly(ε-caprolactone) nanocarriers. The approach extends the applicability of centrifugal ultrafiltration to a wider range of pesticide nanoformulations. We also discuss the effect of dilution on EE and make recommendations to improve the characterisation of nanoparticles-based pesticide nanoformulations in the future.