How to measure release from nanosized carriers?

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.

Surface engineering of lipid nanoparticles: targeted nucleic acid delivery and beyond

Harnessing surface engineering strategies to functionalize nucleic acid-lipid nanoparticles (LNPs) for improved performance has been a hot research topic since the approval of the first siRNA drug, patisiran, and two mRNA-based COVID-19 vaccines, BNT162b2 and mRNA-1273. Currently, efforts have been mainly made to construct targeted LNPs for organ- or cell-type-specific delivery of nucleic acid drugs by conjugation with various types of ligands. In this review, we describe the surface engineering strategies for nucleic acid-LNPs, considering ligand types, conjugation chemistries, and incorporation methods. We then outline the general purification and characterization techniques that are frequently used following the engineering step and emphasize the specific techniques for certain types of ligands. Next, we comprehensively summarize the currently accessible organs and cell types, as well as the other applications of the engineered LNPs. Finally, we provide considerations for formulating targeted LNPs and discuss the challenges of successfully translating the "proof of concept" from the laboratory into the clinic. We believe that addressing these challenges could accelerate the development of surface-engineered LNPs for targeted nucleic acid delivery and beyond.

Developing a robust in vitro release method for a polymeric nanoparticle: Challenges and learnings

Nanomedicines have emerged as a promising approach for targeted therapeutic delivery and specifically as a beneficial alternative to conventional cancer therapies as they can deliver higher concentrations of chemotherapeutic agents at the tumour site compared to healthy tissue, thus providing improved drug efficacy and lower systemic toxicity. Long acting injectables are increasingly becoming the focus of pharmaceutical research, as they can reduce dosing frequency and improve the life quality of patients. Development of an in vitro release (IVR) method for modified release nanomedicines is challenging because of the uniqueness and range of different formulation design approaches, as well as the complex nature of drug release mechanisms which may result in inherent variability. Regulatory guidance on the development of dissolution or release methods for parenteral products is limited relative to oral products. This article details the extensive in vitro release method development work conducted on a polymeric nanoparticle to develop the release media composition and selection of suitable apparatus and sampling technique to separate the released drug from the formulation. The aim was to develop a suitably robust analytical method that generated clinically relevant in vitro release data.

How wound environments trigger the release from Rifampicin-loaded liposomes

BACKGROUND

Chronic wounds often contain high levels of proinflammatory cytokines that prolong the wound-healing process. Patients suffering from these conditions are likely to benefit from topical rifampicin therapy. Although recent research indicates considerable anti-inflammatory properties of the antibiotic, currently, there are no commercial topical wound healing products available. To address this medical need, a liposomal drug delivery system was developed. A mechanistic investigation outlined major influences of wound environments that affect the release kinetics and, as a consequence, local bioavailability.

METHODS

Liposomes were prepared using the thin-film hydration method and subsequently freeze-dried at the pilot scale to improve their stability. We investigated the influence of oxidation, plasma proteins, and lipolysis on the in vitro release of rifampicin and its two main degradation products using the Dispersion Releaser technology. A novel simulated wound fluid provided a standardized environment to study critical influences on the release. It reflects the pathophysiological environment regarding pH, buffer capacity, and protein content.

RESULTS

During storage, the liposomes efficiently protect rifampicin from degradation. After the dispersion of the vesicles in simulated wound fluid, despite the significant albumin binding (>70%), proteins have no considerable effect on the release. Also, the presence of lipase at pathophysiologically elevated concentrations did not trigger the liberation of rifampicin. Surprisingly, the oxidative environment of the wound bed represents the strongest accelerating influence and triggers the release.

CONCLUSION

A stable topical delivery system of rifampicin has been developed. Once the formulation comes in contact with simulated wound fluid, drug oxidation accelerates the release. The influence of lipases that are assumed to trigger the liberation from liposomes depends on the drug-to-lipid ratio. Considering that inflamed tissues exhibit elevated levels of oxidative stress, the trigger mechanism identified for rifampicin contributes to targeted drug delivery.

Reliable Kinetics for Drug Delivery with a Microfluidic Device Integrated with the Dialysis Bag

The clinical success of a drug delivery system turns back to performing experiments with more reliable data. The dialysis bag has been one of the most employed technologies to monitor drug release from nanocarriers, membranes, and scaffolds. Unfortunately, this technology has several challenges regarding the accuracy of the obtained results. In this study, the development of a new system by integrating a microfluidic device and dialysis bag named "MF-dialysis" was carried out to evaluate the accuracy of the reported data. The release study was performed focusing on two drug delivery systems: (i) nanocarrier: Artemisia Absinthium extract-loaded soy protein isolate nanoparticle and (ii) sodium alginate film loaded with the nanocarrier. The obtained nanocarrier was analyzed by SEM, DLS, and zeta potential. The final experimental data were modeled using SigmaPlot software. Based on the results, two distinct but fitted models for the dialysis bag (power model, R² = 0.99) and MF-dialysis (exponential model, R² = 0.95) were obtained. MF-dialysis approved that after a while, NPs and films showed more drug release compared to the dialysis bag. To sum up, the MF-dialysis system can be a good candidate for a quick and more reliable study of drug delivery systems.

In vitro-in vivo correlation in nanocarriers: From protein corona to therapeutic implications

Understanding and establishing a link between the physicochemical characteristics of nanoparticles (NPs) and their biological interactions poses to be a great challenge in the field of nanotherapeutics. Recent analytical advancements concerning bio-nanointerfaces have accelerated the quest to comprehend the fate of nanocarrier systems in vivo. Scientists have discovered that protein corona, an adsorbed layer of biomolecules on the surface of NPs takes a leading part in interacting with cells and in the cellular uptake process, thereby determining the in vivo behaviour of NPs. Another useful method to assess the in vivo fate of NPs is by performing dissolution testing. This forms the basis for in vitro in vivo correlation (IVIVC), relating in vitro dissolution of NPs and their in vivo properties. Scientists are continuously directing their efforts towards establishing IVIVC for different nanocarrier systems while concurrently gaining insights into protein corona. This review primarily summarizes the importance of protein corona and its interaction with nanoparticles. It also gives an insight into the factors affecting the interaction and various in vitro dissolution media used for varied nanocarrier systems. The article concludes with a discussion of the limitations of IVIVC modelling and its position from a regulatory perspective.

Myocardial Cell Preservation from Potential Cardiotoxic Drugs: The Role of Nanotechnologies

Cardiotoxic therapies, whether chemotherapeutic or antibiotic, represent a burden for patients who may need to interrupt life-saving treatment because of serious complications. Cardiotoxicity is a broad term, spanning from forms of heart failure induction, particularly left ventricular systolic dysfunction, to induction of arrhythmias. Nanotechnologies emerged decades ago. They offer the possibility to modify the profiles of potentially toxic drugs and to abolish off-target side effects thanks to more favorable pharmacokinetics and dynamics. This relatively modern science encompasses nanocarriers (e.g., liposomes, niosomes, and dendrimers) and other delivery systems applicable to real-life clinical settings. We here review selected applications of nanotechnology to the fields of pharmacology and cardio-oncology. Heart tissue-sparing co-administration of nanocarriers bound to chemotherapeutics (such as anthracyclines and platinum agents) are discussed based on recent studies. Nanotechnology applications supporting the administration of potentially cardiotoxic oncological target therapies, antibiotics (especially macrolides and fluoroquinolones), or neuroactive agents are also summarized. The future of nanotechnologies includes studies to improve therapeutic safety and to encompass a broader range of pharmacological agents. The field merits investments and research, as testified by its exponential growth.

Biopredictive tools for the development of injectable drug products

INTRODUCTION

Biopredictive release tests are commonly used in the evaluation of oral medicines. They support decision-making in formulation development and allow predictions of the expected in-vivo performances. So far, there is limited experience in the application of these methodologies to injectable drug products.

AREAS COVERED

Parenteral drug products cover a variety of dosage forms and administration sites including subcutaneous, intramuscular, and intravenous injections. In this area, developing biopredictive and biorelevant methodologies often confronts us with unique challenges and knowledge gaps. Here, we provide a formulation-centric approach and explain the key considerations and workflow when designing biopredictive assays. Also, we outline the key role of computational methods in achieving clinical relevance and put all considerations into context using liposomal nanomedicines as an example.

EXPERT OPINION

Biopredictive tools are the need of the hour to exploit the tremendous opportunities of injectable drug products. A growing number of biopharmaceuticals such as peptides, proteins, and nucleic acids require different strategies and a better understanding of the influences on drug absorption. Here, our design strategy must maintain the balance of robustness and complexity required for effective formulation development.

Nanocarrier Drug Delivery Systems: Characterization, Limitations, Future Perspectives and Implementation of Artificial Intelligence

There has been an increasing demand for the development of nanocarriers targeting multiple diseases with a broad range of properties. Due to their tiny size, giant surface area and feasible targetability, nanocarriers have optimized efficacy, decreased side effects and improved stability over conventional drug dosage forms. There are diverse types of nanocarriers that have been synthesized for drug delivery, including dendrimers, liposomes, solid lipid nanoparticles, polymersomes, polymer-drug conjugates, polymeric nanoparticles, peptide nanoparticles, micelles, nanoemulsions, nanospheres, nanocapsules, nanoshells, carbon nanotubes and gold nanoparticles, etc. Several characterization techniques have been proposed and used over the past few decades to control and predict the behavior of nanocarriers both in vitro and in vivo. In this review, we describe some fundamental in vitro, ex vivo, in situ and in vivo characterization methods for most nanocarriers, emphasizing their advantages and limitations, as well as the safety, regulatory and manufacturing aspects that hinder the transfer of nanocarriers from the laboratory to the clinic. Moreover, integration of artificial intelligence with nanotechnology, as well as the advantages and problems of artificial intelligence in the development and optimization of nanocarriers, are also discussed, along with future perspectives.

Ethanolic Fenugreek Extract: Its Molecular Mechanisms against Skin Aging and the Enhanced Functions by Nanoencapsulation

Fenugreek, or Trigonella foenum-graecum L. (family Leguminosae) seeds, are typically used as food supplements to increase postnatal lactation. Fenugreek extract displays antioxidative and anti-inflammatory properties, but its mechanisms against skin aging have not been exploited. In this research, we are the first to define an in vitro collagenase inhibitory activity of fenugreek extract (IC₅₀ = 0.57 ± 0.02 mg/mL), which is 2.6 times more potent than vitamin C (IC₅₀ = 1.46 mg/mL). Nanoencapsulation has been applied to improve the extract stability, and subsequently enhanced its bioactivities. Liponiosome encapsulating fenugreek extract (LNF) was prepared using a high-speed homogenizer, resulting in homogeneous spherical nanoparticles with sizes in the range of 174.7 ± 49.2 nm, 0.26 ± 0.04 in PdI, and 46.6 ± 7.4% of entrapment efficiency. LNF formulation significantly facilitated a sustained release and significantly enhanced skin penetration over the extracts, suggesting a potential use of LNF for transdermal delivery. The formulated LNF was highly stable, not toxic to human fibroblast, and was able to enhance cell viability, collagen production, and inhibit MMP1, MMP9, IL-6, and IL-8 secretions compared to the extract in the co-cultured skin model. Therefore, ethanolic fenugreek extract and its developed LNF display molecular mechanisms against skin aging and could potentially be used as an innovative ingredient for the prevention of skin aging.

Need for Expansion of Pharmacy Education Globally for the Growing Field of Nanomedicine

The emerging landscape of nanomedicine includes a wide variety of active pharmaceutical ingredients and drug formulations. Their design provides nanomedicines with unique features leading to improved pharmacokinetics and pharmacodynamics. They are manufactured using conventional or biotechnological manufacturing processes. Their physical characteristics are vastly different from traditional small-molecule drugs. Pharmacists are important members of the multi-disciplinary team of scientists involved in their development and clinical application. Consequently, their training should lead to an understanding of the complexities associated with the production and evaluation of nanomedicines. Therefore, student pharmacists, post-doctoral researchers, and trainees should be given more exposure to this rapidly evolving class of therapeutics. This commentary will provide an overview of nanomedicine education within the selection of pharmacy programs globally, discuss the current regulatory challenges, and describe different approaches to incorporate nanomedicine science in pharmacy programs around the world.

Overcoming hydrolytic degradation challenges in topical delivery: non-aqueous nano-emulsions

INTRODUCTION

Non-aqueous nano-emulsions (NANEs) are colloidal lipid-based dispersions with nano-sized droplets formed by mixing two immiscible phases, none of which happens to be an aqueous phase. Their ability to incorporate water and oxygen sensitive drugs without any susceptibility to degradation makes them the optimum dosage form for such candidates. In NANEs, polar liquids or polyols replace the aqueous phase while surfactants remain same as used in conventional emulsions. They are a part of the nano-emulsion family albeit with substantial difference in composition and application.

AREAS COVERED

The present review provides a brief insight into the strategies of loading water-sensitive drugs into NANEs. Further advancement in these anhydrous systems with the use of solid particulate surfactants in the form of Pickering emulsions is also discussed.

EXPERT OPINION

NANEs offer a unique platform for delivering water-sensitive drugs by loading them in anhydrous formulation. The biggest advantage of NANEs vis-à-vis the other nano-cargos is that they can also be prepared without using equipment-intensive techniques. However, the use of NANEs in drug delivery is quite limited. Looking at the small number of studies available in this direction, a need for further research in this field is required to explore this delivery system further.

Nanomedicine at the crossroads - A quick guide for IVIVC

For many years, nanomedicine is pushing the boundaries of drug delivery. When applying these novel therapeutics, safety considerations are not only a key concern when entering clinical trials but also an important decision point in product development. Standing at the crossroads, nanomedicine may be able to escape the niche markets and achieve wider acceptance by the pharmaceutical industry. While there is a new generation of drug delivery systems, the extracellular vesicles, standing on the starting line, unresolved issues and new challenges emerge from their translation from bench to bedside. Some key features of injectable nanomedicines contribute to the predictability of the pharmacological and toxicological effects. So far, only a few of the physicochemical attributes of nanomedicines can be justified by a direct mathematical relationship between the in vitro and the in vivo responses. To further develop extracellular vesicles as drug carriers, we have to learn from more than 40 years of clinical experience in liposomal delivery and pass on this knowledge to the next generation. Our quick guide discusses relationships between physicochemical characteristics and the in vivo response, commonly referred to as in vitro-in vivo correlation. Further, we highlight the key role of computational methods, lay open current knowledge gaps, and question the established design strategies. Has the recent progress improved the predictability of targeted delivery or do we need another change in perspective?

An Update to Dialysis-Based Drug Release Testing-Data Analysis and Validation Using the Pharma Test Dispersion Releaser

Currently, a wide variety of complex non-oral dosage forms are entering the global healthcare market. Although many assays have been described in recent research, harmonized procedures and standards for testing their in vitro performance remain widely unexplored. Among others, dialysis-based techniques such as the Pharma Test Dispersion Releaser are developed for testing the release of drugs from nanoparticles, liposomes, or extracellular vesicle preparations. Here, we provide advanced strategies and practical advice for the development and validation of dialysis-based techniques, including documentation, analysis, and interpretation of the raw data. For this purpose, key parameters of the release assay, including the hydrodynamics in the device at different stirring rates, the selectivity for particles and molecules, as well as the effect of excipients on drug permeation were investigated. At the highest stirring rate, a more than twofold increase in the membrane permeation rate (from 0.99 × 10⁻³ to 2.17 × 10⁻³ cm²/h) was observed. Additionally, we designed a novel computer model to identify important quality parameters of the dialysis experiment and to calculate error-corrected release profiles. Two hydrophilic creams of diclofenac, Voltaren^® Emulgel, and Olfen^® gel, were tested and provide first-hand evidence of the robustness of the assay in the presence of semisolid dosage forms.

Reliable release testing for nanoparticles with the NanoDis System, an innovative sample and separate technique

One of the critical quality attributes of nanoparticle formulations is drug release. Their release properties should therefore be well characterized with predictive and discriminative methods. However, there is presently still no standard method for the release testing of extended release nanoformulations. Dialysis techniques are widely used in the literature but suffer from severe drawbacks. Burst release of formulations can be masked by slow permeation kinetics of the free drug through the dialysis membrane, saturation in the membrane, and absence of agitation in the membrane. In this study, the release profile of poly(lactic co-glycolic) (PLGA) nanocapsules loaded with all-trans retinoic acid was characterized using an innovative sample and separate set-up, the NanoDis System, and compared to the release profile measured with a dialysis technique. The NanoDis System showed clear superiority over the dialysis method and was able to accurately characterize the burst release from the capsules and furthermore discriminate between different all-trans retinoic acid nanoparticle formulations.

Simulate SubQ: The Methods and the Media

For decades, there has been a growing interest in injectable subcutaneous formulations to improve the absorption of drugs into the systemic circulation and to prolong their release over a longer period. However, fluctuations in the blood plasma levels together with bioavailability issues often limit their clinical success. This warrants a closer look at the performance of long-acting depots, for example, and their dependence on the complex interplay between the dosage form and the physiological microenvironment. For this, biopredictive performance testing is used for a thorough understanding of the biophysical processes affecting the absorption of compounds from the injection site in vivo and their simulation in vitro. In the present work, we discuss in vitro methodologies including methods and media developed for the subcutaneous route of administration on the background of the most relevant absorption mechanisms. Also, we highlight some important knowledge gaps and shortcomings of the existing methodologies to provide the reader with a better understanding of the scientific evidence underlying these models.

Injectable drug delivery systems of doxorubicin revisited: In vitro-in vivo relationships using human clinical data

A growing number of nanomedicines entered the clinical trials and improved our understanding of the in vivo responses expected in humans. The in vitro drug release represents an important critical quality attribute involved in pharmacokinetics. Establishing in vitro-in vivo relationships for nanomedicines requires a careful analysis of the clinical data with respect to the unique differences between drugs and nanomedicines. Also, the biorelevant assay must reflect the release mechanism of the carrier. Four drug delivery systems of doxorubicin were evaluated for their in vitro release behavior under biorelevant conditions using the dispersion releaser. The pharmacokinetics observed during the first-in-men clinical trials were analyzed using a custom-made physiologically-based nanocarrier biopharmaceutics model. The drug product Lipodox® and the clinical candidate NanoCore-7.4 were evaluated to validate the model. Afterward, the in vivo performances of the preclinical candidates NanoCore-6.4 and doxorubicin-loaded nano-cellular vesicle technology systems (an extracellular vesicle preparation) were predicted. In vitro and in vivo release were in good correlation as indicated by the coefficients of determination of 0.98648 (NanoCore-7.4) and 0.94107 (Lipodox®). The predictions required an estimation of the carrier half-life in blood circulation leading to considerable uncertainty. Still, the simulations narrow down the possible scenarios in the clinical evaluation of nanomedicines and provide a valuable addition to animal studies.

Controlling the semi-permeability of protein nanocapsules influences the cellular response to macromolecular payloads

Nanocapsules are an excellent platform for the delivery of macromolecular payloads such as proteins, nucleic acids or polyprodrugs, since they can both protect the sensitive cargo and target its delivery to the desired site of action. However, the release of macromolecules from nanocapsules remains a challenge due to their restricted diffusion through the nanoshell compared to small molecule cargo. Here, we designed degradable protein nanocapsules with varying crosslinking densities of the nanoshell to control the release of model macromolecules. While the crosslinking did not influence the degradability of the capsules by natural proteases, it significantly affected the release profiles. Furthermore, the optimized protein nanocapsules were successfully used to deliver and effectively release a bioactive macromolecular vaccine adjuvant in vitro and, thus, can be used as an efficient platform for the design of potential nanovaccines.

UNGAP best practice for improving solubility data quality of orally administered drugs

An important goal of the European Cooperation in Science and Technology (COST) Action UNGAP (UNderstanding Gastrointestinal Absorption-related Processes, www.ungap.eu) is to improve standardization of methods relating to the study of oral drug absorption. Solubility is a general term that refers to the maximum achievable concentration of a compound dissolved in a liquid medium. For orally administered drugs, relevant information on drug properties is crucial during drug (product) development and at the regulatory level. Collection of reliable and reproducible solubility data requires careful application and understanding of the limitations of the selected experimental method. In addition, the purity of a compound and its solid state form, as well as experimental parameters such as temperature of experimentation, media related factors, and sample handling procedures can affect data quality. In this paper, an international consensus developed by the COST UNGAP network on recommendations for collecting high quality solubility data for the development of orally administered drugs is proposed.

Progress in the development of stabilization strategies for nanocrystal preparations

In recent years, nanocrystal technology has been extensively investigated. Due to the submicron particle size and unique physicochemical properties of nanocrystals, they overcome the problems of low drug solubility and poor bioavailability. Although the structures of nanocrystals are simple, the further development of these materials is hindered by their stability. Drug nanocrystals with particle sizes of 1∼1000 nm usually require the addition of stabilizers such as polymers or surfactants to enhance their stability. The stability of nanocrystal suspensions and the redispersibility of solid nanocrystal drugs are the key factors for the large-scale production of nanocrystal preparations. In this paper, the factors that affect the stability of drug nanocrystal preparations are discussed, and related methods for solving the stability problem are put forward.

Recent Progress in Drug Release Testing Methods of Biopolymeric Particulate System

Biopolymeric microparticles have been widely used for long-term release formulations of short half-life chemicals or synthetic peptides. Characterization of the drug release from microparticles is important to ensure product quality and desired pharmacological effect. However, there is no official method for long-term release parenteral dosage forms. Much work has been done to develop methods for in vitro drug release testing, generally grouped into three major categories: sample and separate, dialysis membrane, and continuous flow (flow-through cell) methods. In vitro drug release testing also plays an important role in providing insight into the in vivo performance of a product. In vitro release test with in vivo relevance can reduce the cost of conducting in vivo studies and accelerate drug product development. Therefore, investigation of the in vitro–in vivo correlation (IVIVC) is increasingly becoming an essential part of particulate formulation development. This review summarizes the principles of the in vitro release testing methods of biopolymeric particulate system with the recent research articles and discusses their characteristics including IVIVC, accelerated release testing methods, and stability of encapsulated drugs.

The key role of the drug self-aggregation ability to obtain optimal nanocarriers based on aromatic-aromatic drug-polymer interactions

The efficient association and controlled release of hydrophilic and aromatic low molecular-weight drugs (HALMD) still remains a challenge due to their relatively weak interactions with excipients and strong affinity to water. Considering that a wide variety of drugs to treat chronic diseases are HALMD, their inclusion in polymeric nanoparticles (NPs) constitutes an attractive possibility by providing to these drugs with controllable physiochemical properties, preventing crisis episodes, decreasing dose-dependent side effects and promoting therapeutic adhesiveness. However, the strong interaction of HALMD with the aqueous medium jeopardizes their encapsulation and controlled release. In this work, the role of the self-assembly tendency of HALMD on their association with the aromatic excipient poly(sodium 4-styrensulfonate) (PSS) to form NPs is studied. For this aim, the widely used drugs amitriptyline (AMT), promethazine (PMZ), and chlorpheniramine (CPM) are selected due to their well described critical aggregation concentration (cac) (36 mM for AMT, 36 mM for PMZ, and 69.5 mM for CPM). These drugs undergo aromatic-aromatic interactions with the polymer, which stabilize their mutual binding, as seen by NMR. The simple mixing of solutions of opposite charged molecules (drug + PSS) allowed obtaining NPs. Importantly, comparing the three drugs, the formation of NPs occurred at significantly lower absolute concentration and significantly lower drug/polymer ratio as the cac takes lower values, indicating a stronger binding to the polymer, as also deduced from the respective drug/polymer dissociation constant values. In addition, the number of formed NPs is similar for all formulations, even though a much lower concentration of the drug and polymer is present in systems comprising lower cac. The obtained NPs are spheroidal and present size between 100 and 160 nm, low polydispersity (≤0.3) and negative zeta potential (from -30 to -60 mV). The association efficiency reaches values ≥ 83% and drug loading could achieve values up to 68% (never evidenced before for systems comprising HALMD). In addition, drug release studies are also significantly influenced by cac, providing more prolonged release for AMT and PMZ (lower cac), whose delivery profiles adjust to the Korsmeyer-Peppas equation. As a novelty of this work, a synergic contribution of drug self-association tendency and aromatic-aromatic interaction between the drug and polymers is highlighted, a fact that could be crucial for the rational design and development of efficient drug delivery systems.

Comparison of imidacloprid, propiconazole, and nanopropiconazole effects on the development, behavior, and gene expression biomarkers of the Pacific oyster (Magallana gigas)

Coastal areas are final recipients of various contaminants including pesticides. The effects of pesticides on non-target organisms are often unclear, especially at environmentally relevant concentrations. This study investigated the impacts of insecticide imidacloprid (IMI) and fungicide propiconazole (PRO), some of the most detected pesticides in the Arcachon Bay in France. This work also included the research of propiconazole nanoformulation (nanoPRO). The effects were assessed studying the development of the early life stages of the Pacific oyster (Magallana gigas). Oyster embryos were exposed for 24, 30, and 42 h (depending on the endpoint) at 24 °C to environmentally relevant concentrations of the two pesticides as well as to nanoPRO. The research focused on sublethal endpoints such as the presence of developmental malformations, alterations of locomotion patterns, or changes in the gene expression levels. No developmental abnormalities were observed after exposure to environmental concentrations detected in the Arcachon Bay in recent years (maximal detected concentration of IMI and PRO were 174 ng/L and 29 ng/L, respectively). EC₅₀ of PRO and nanoPRO were comparable, 2.93 ± 1.35 and 2.26 ± 1.36 mg/L, while EC₅₀ of IMI exceeded 200 mg/L. IMI did not affect larval behavior. PRO affected larval movement trajectory and decreased average larvae swimming speed (2 μg/L), while nanoPRO increased the maximal larvae swimming speed (0.02 μg/L). PRO upregulated especially genes linked to reactive oxygen species (ROS) production and detoxification. NanoPRO effects on gene expression were less pronounced - half of the genes were altered in comparison with PRO. IMI induced a strong dose-response impact on the genes linked to the detoxification, ROS production, cell cycle, and apoptosis regulation. In conclusion, our results suggest that current pesticide concentrations detected in the Arcachon Bay are safe for the Pacific oyster early development, but they might have a small direct effect via altered gene expressions, whose longer-term impacts cannot be ruled out.

Development of a Nanostructured Lipid Carrier (NLC) by a Low-Energy Method, Comparison of Release Kinetics and Molecular Dynamics Simulation

Lipid nanocarriers have a great potential for improving the physicochemical characteristics and behavior of poorly water-soluble drugs, such as aqueous dispersibility and oral bioavailability. This investigation presents a novel nanostructured lipid carrier (NLC) based on a mixture of solid lipid glycerides, fatty acid esters of PEG 1500 (Gelucire^® 44/14), and an oil mix composed of capric and caprylic triglycerides (Miglyol^® 812). These NLCs were developed by a simple low-energy method based on melt emulsification to yield highly encapsulating and narrowly distributed nanoparticles (~100 nm, PdI = 0.1, and zeta potential = ~−10 mV). Rhodamine 123 was selected as a poorly water-soluble drug model and owing to its spectroscopic properties. The novel NLCs were characterized by dynamic light scattering (DLS), zeta potential, nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and colloidal stability. The drug release was determined through a dialysis bag and vertical Franzs’ cells to provide insights about the methods’ suitability, revealing similar performance regardless of their different fluid dynamics. Rhodamine 123 followed a characteristic biphasic release profile owing to the swelling of the hydrophilic polymer coating and diffusion process from the lipid core as revealed by the Korsmeyers–Peppas kinetic modeling. Moreover, to elucidate the formation and incorporation of Rhodamine 123 into the NLC core, several molecular dynamics simulations were conducted. The temperature was shown to be an important condition to improve the formation of the nanoparticles. In addition, the liquid lipid incorporation to the formulation forms nanoparticles with imperfect centers, in contrast to nanoparticles without it. Moreover, Miglyol^® 812 improves hydrophobic molecule solubility. These results suggest the potential of novel NLC as a drug delivery system for poorly water-soluble drugs.

Asymmetric flow field-flow fractionation as a multifunctional technique for the characterization of polymeric nanocarriers

The importance of polymeric nanocarriers in the field of drug delivery is ever-increasing, and the accurate characterization of their properties is paramount to understand and predict their behavior. Asymmetric flow field-flow fractionation (AF4) is a fractionation technique that has gained considerable attention for its gentle separation conditions, broad working range, and versatility. AF4 can be hyphenated to a plurality of concentration and size detectors, thus permitting the analysis of the multifunctionality of nanomaterials. Despite this potential, the practical information that can be retrieved by AF4 and its possible applications are still rather unfamiliar to the pharmaceutical scientist. This review was conceived as a primer that clearly states the "do's and don'ts" about AF4 applied to the characterization of polymeric nanocarriers. Aside from size characterization, AF4 can be beneficial during formulation optimization, for drug loading and drug release determination and for the study of interactions among biomaterials. It will focus mainly on the advances made in the last 5 years, as well as indicating the problematics on the consensus, which have not been reached yet. Methodological recommendations for several case studies will be also included.

Exploring the Interplay between Drug Release and Targeting of Lipid-Like Polymer Nanoparticles Loaded with Doxorubicin

Targeted delivery of doxorubicin still poses a challenge with regards to the quantities reaching the target site as well as the specificity of the uptake. In the present approach, two colloidal nanocarrier systems, NanoCore-6.4 and NanoCore-7.4, loaded with doxorubicin and characterized by different drug release behaviors were evaluated in vitro and in vivo. The nanoparticles utilize a specific surface design to modulate the lipid corona by attracting blood-borne apolipoproteins involved in the endogenous transport of chylomicrons across the blood–brain barrier. When applying this strategy, the fine balance between drug release and carrier accumulation is responsible for targeted delivery. Drug release experiments in an aqueous medium resulted in a difference in drug release of approximately 20%, while a 10% difference was found in human serum. This difference affected the partitioning of doxorubicin in human blood and was reflected by the outcome of the pharmacokinetic study in rats. For the fast-releasing formulation NanoCore-6.4, the AUC_0→1h was significantly lower (2999.1 ng × h/mL) than the one of NanoCore-7.4 (3589.5 ng × h/mL). A compartmental analysis using the physiologically-based nanocarrier biopharmaceutics model indicated a significant difference in the release behavior and targeting capability. A fraction of approximately 7.310–7.615% of NanoCore-7.4 was available for drug targeting, while for NanoCore-6.4 only 5.740–6.057% of the injected doxorubicin was accumulated. Although the targeting capabilities indicate bioequivalent behavior, they provide evidence for the quality-by-design approach followed in formulation development.

Sustained-release hot melt extrudates of the weak acid TMP-001: A case study using PBB modelling

Over the last 30 years, hot melt extrusion has become a leading technology in the manufacture of amorphous drug delivery systems. Mostly applied as an 'enabling formulation' for poorly soluble compounds, application in the design of sustained-release formulations increasingly attracts the attention of the pharmaceutical industry. The drug candidate TMP-001 is currently under evaluation for the early treatment of Multiple Sclerosis. Although this weak acid falls into class II of the Biopharmaceutics Classification System, the compound exhibits high solubility in the upper intestine resulting in high peroral bioavailability. In the present studies, four different formulation prototypes varying in their sustained-release behavior were developed, using L-arginine as a pore-forming agent in concentrations ranging between 0 and 20%. Initially, biorelevant release testing was applied to assess the dissolution behavior of the prototypes. For these formulations, a total drug release of 44.7%, 64.6%, 75%, and 90.5% was achieved in FaSSIF-v2 after 24 h. Two candidates were selected for further characterization considering the crystal structure and the physical stability of the amorphous state of TMP-001 in the formulations together with the release behavior in Level II biorelevant media. Our findings indicate L-arginine as a valuable excipient in the formulation of hot melt extrudates, as its presence led to a considerable stabilization of the amorphous state and favorably impacted the milling process and release behavior of TMP-001. To properly evaluate the proposed formulations and the importance of colonic dissolution and absorption on the overall bioavailability, a physiologically-based biopharmaceutics model was used.

Development of nanoparticle-based orodispersible palatable pediatric formulations

Despite a collaborative effort towards developing suitable oral drug products for pediatrics over the past decade, appropriate pediatric dosage forms have remained lacking due to special considerations in dose flexibility, swallowability, palatability, and safety of excipients for pediatrics. The present research aims to develop a nanoparticle-based orodispersible pediatric drug delivery platform to improve oral bioavailability and taste of poorly water-soluble and unpalatable therapeutics. Two Biopharmaceutics Classification System II/IV compounds lopinavir (LPV) and ritonavir (RTV) with unpleasant taste were chosen as the model compounds. LPV and RTV Eudragit® E PO nanoparticles (NP) were prepared using a nanoprecipitation method and their key quality attributes and taste-masking effect were evaluated. Moreover, in vitro dissolution testing was conducted at simulated gastrointestinal pH conditions. The in vivo bioavailability of the developed NP formulations was assessed using a rat model. Following the formulation optimization, over 98% encapsulation efficiency was obtained for both LPV and RTV NP and both drugs remained amorphous in its respective NP. LPV/RTV NP combination (4/1, w/w) showed comparable in vitro dissolution to that of the commercial LPV/RTV tablet (Kaletra®). In addition, the taste-masking effect of the developed NP formulations was confirmed by an E-tongue study. The lyophilized LPV and RTV NP were completely dispersible in water within 7 sec and remained stable at 4 ± 2 °C over three months. Lastly, the pharmacokinetic study demonstrated that the LPV/RTV NP combination (4/1, w/w) had improved oral bioavailability compared to Kaletra® and their corresponding raw drug powders. The results demonstrated a novel nanoparticle-based orodispersible platform that is capable of improving oral bioavailability and taste of poorly water-soluble and unpalatable therapeutics for pediatric use.

Predicting drug release and degradation kinetics of long-acting microsphere formulations of tacrolimus for subcutaneous injection

Today, tacrolimus represents a cornerstone of immunosuppressive therapy for liver and kidney transplants and remains subject of preclinical and clinical investigations, aiming at the development of long-acting depot formulations for subcutaneous injection. One major challenge arises from establishing in vitro-in vivo correlations due to the absence of meaningful in vitro methods predictive for the in vivo situation, together with a strong impact of multiple kinetic processes on the plasma concentration-time profile. In the present approach, two microsphere formulations were compared with regards to their in vitro release and degradation characteristics. A novel biorelevant medium provided the physiological ion and protein background. Release was measured using the dispersion releaser technology under accelerated conditions. A release of 100% of the drug from the carrier was achieved within 7 days. The capability of the in vitro performance assay was verified by the level A in vitro-in vivo correlation analysis. The contributions of in vitro drug release, drug degradation, diffusion rate and lymphatic transport to the absorption process were quantitatively investigated by means of a mechanistic modelling approach. The degradation rate, together with release and diffusion characteristics provides an estimate of the bioavailability and therefore can be a guide to future formulation development.

Predicting the environmental emissions arising from conventional and nanotechnology-related pharmaceutical drug products

Today, environmental pollution with pharmaceutical drugs and their metabolites poses a major threat to the aquatic ecosystems. Active substances such as fenofibrate, are processed to pharmaceutical drug formulations before they are degraded by the human body and released into the wastewater. Compared to the conventional product Lipidil® 200, the pharmaceutical product Lipidil 145 One® and Ecocaps take advantage of nanotechnology to improve uptake and bioavailability of the drug in humans. In the present approach, a combination of in vitro drug release studies and physiologically-based biopharmaceutics modeling was applied to calculate the emission of three formulations of fenofibrate (Lipidil® 200, Lipidil 145 One®, Ecocaps) into the environment. Special attention was paid to the metabolized and non-metabolized fractions and their individual toxicity, as well as to the emission of nanomaterials. The fish embryo toxicity test revealed a lower aquatic toxicity for the metabolite fenofibric acid and therefore an improved toxicity profile. When using the microparticle formulation Lipidil® 200, an amount of 126 mg of non-metabolized fenofibrate was emitted to the environment. Less than 0.05% of the particles were in the lower nanosize range. For the nanotechnology-related product Lipidil 145 One®, the total drug emission was reduced by 27.5% with a nanomaterial fraction of approximately 0.5%. In comparison, the formulation prototype Ecocaps reduced the emission of fenofibrate by 42.5% without any nanomaterials entering the environment. In a streamlined life cycle assessment, the lowered dose in combination with a lowered drug-to-metabolite ratio observed for Ecocaps led to a reduction of the full life cycle impacts of fenofibrate with a reduction of 18% reduction in the global warming potential, 61% in ecotoxicity, and 15% in human toxicity. The integrated environmental assessment framework highlights the outstanding potential of advanced modeling technologies to determine environmental impacts of pharmaceuticals during early drug development using preclinical in vitro data.

Design of Chitosan Nanocapsules with Compritol 888 ATO® for Imiquimod Transdermal Administration. Evaluation of Their Skin Absorption by Raman Microscopy

PURPOSE

Design imiquimod-loaded chitosan nanocapsules for transdermal delivery and evaluate the depth of imiquimod transdermal absorption as well as the kinetics of this absorption using Raman Microscopy, an innovative strategy to evaluate transdermal absorption. This nanovehicle included Compritol 888ATO®, a novel excipient for formulating nanosystems whose administration through the skin has not been studied until now.

METHODS

Nanocapsules were made by solvent displacement method and their physicochemical properties was measured by DLS and laser-Doppler. For transdermal experiments, newborn pig skin was used. The Raman spectra were obtained using a laser excitation source at 532 nm and a 20/50X oil immersion objective.

RESULTS

The designed nanocapsules, presented nanometric size (180 nm), a polydispersity index <0.2 and a zeta potential +17. The controlled release effect of Compritol was observed, with the finding that half of the drug was released at 24 h in comparison with control (p < 0.05). It was verified through Raman microscopy that imiquimod transdermal penetration is dynamic, the nanocapsules take around 50 min to penetrate the stratum corneum and 24 h after transdermal administration, the drug was in the inner layers of the skin.

CONCLUSIONS

This study demonstrated the utility of Raman Microscopy to evaluate the drugs transdermal penetration of in the different layers of the skin. Graphical Abstract New imiquimod nanocapsules: evaluation of their skin absorption by Raman Microscopy and effect of the compritol 888ATO® in the imiquimod release profile.

Purification and characterization of the major protein isolated from Semen Armeniacae Amarum and the properties of its thermally induced nanoparticles

From the aqueous extract of Semen Armeniacae Amarum, a major protein isolate was purified and characterized as a novel member of the 11S globulin family, which is composed of three polypeptides linked by disulfide bond. Furthermore, the feasibility of using the isolated protein for fabricating nanocarriers was investigated. The results indicate that thermal treatment of the globulin induced the rearrangement of the disulfide bond to form homodimers of acid polypeptides during the formation of nanoparticles. The harvested nanoparticles produced by heat-induced assembly are spherical in shape, with an average size of 92 nm and exhibited low cytotoxicity to L-02 and MDCK cell lines. These nanoparticles are capable to encapsulate paclitaxel, estimated the maximum encapsulation efficiency of paclitaxel loaded to the nanoparticles was 92.6% and the maximum release of paclitaxel was 57.4%. This research suggests that the screening of traditional herbal extracts could provide a novel source of protein nanocarriers.

Nanomedicines - Tiny particles and big challenges

After decades of research, nanotechnology has been used in a broad array of biomedical products including medical devices, drug products, drug substances, and pharmaceutical-grade excipients. But like many great achievements in science, there is a fine balance between the risks and opportunities of this new technology. Some materials and surface structures in the nanosize range can exert unexpected toxicities and merit a more detailed safety assessment. Regulatory agencies such as the United States Food and Drug Administration or the European Medicines Agency have started dealing with the potential risks posed by nanomaterials. Considering that a thorough characterization is one of the key aspects of controlling such risks this review presents the regulatory background of nanosafety assessment and provides some practical advice on how to characterize nanomaterials and drug formulations. Further, the challenges of how to maintain and monitor pharmaceutical quality through a highly complex production processes will be discussed.

Kinetic Study of Controlled Asphaltene Inhibitor Release from Nanoemulsions

Asphaltene aggregation and subsequent precipitation in the nonpolar medium may have a profound effect on plugging wellbores and production equipment. Continuing our work on controlled release of asphaltene inhibitor (AI) by using nanoemulsions (NEs), this work provides new evidence about long-term asphaltene stability by using optical measurement and reveals the kinetic processes of inhibitor transport/release mechanisms. Multiple light scattering (Turbiscan) and dynamic light scattering have been used to study "in situ" the effectiveness and performance of the proposed controlled release in three cases of asphaltene aggregation/precipitation in the presence of: (i) strong organic acids (dodecyl benzene sulfonic acid, DBSA), (ii) NEs (blank NEs), and (iii) NEs loaded with DBSA (DBSA NEs). The results suggested that the new approach reduced the amount of AI by ∼20 times and achieved high asphaltene inhibition efficiency of ∼84% with a prolonged release time. A mechanistic understanding of the controlled release effect was proposed based on the effect of DBSA NEs on the asphaltene particle morphology variation, which was related to the hydrophilicity of DBSA and the strong intermolecular interactions among all DBSA NE components. The release mechanism of the AI from the NE was evaluated using eight release models and was found to follow the Korsmeyer-Peppas kinetic model.

A dialysis-based in vitro drug release assay to study dynamics of the drug-protein transfer of temoporfin liposomes

Today, a growing number of nanotherapeutics is utilized to deliver poorly soluble compounds using the intravenous route of administration. The drug release and the direct transfer of the active pharmaceutical ingredient to serum proteins plays an important role in bioavailability and accumulation of the drug at the target site. It is closely related to the formation of a protein corona as well as the plasma protein binding of the compound. In the present study, two in vitro drug release methods, the flow-through cell and the dispersion releaser technology, were evaluated with regards to their capability to measure a time-resolved profile of the serum protein binding. In this context, the photosensitizer temoporfin and temoporfin-loaded liposomes were tested. While in the fine capillaries of the flow-through cell a rapid agglomeration of proteins occurred, the dispersion releaser technology in combination with the four-step model enabled the measurement of the transfer of drugs from liposomes to proteins. In presence of 10% of fetal calf serum approximately 20% of the model compound temoporfin were bound to serum proteins within the first 3 h. At higher serum concentration this binding remained stable for approximately 10 h.

Interpreting non-linear drug diffusion data: Utilizing Korsmeyer-Peppas model to study drug release from liposomes

The aim of this work was to clarify the dynamics behind the influence of ionic strength on the changes in drug release from large unilamellar vesicles (LUVs). For this purpose, we have investigated the transport of two different model drugs (caffeine and hydrocortisone) formulated into liposomes through different types of barriers with different retention properties (regenerated cellulose and the newly introduced biomimetic barrier, Permeapad®). Drug release from liposomes was studied utilizing the standard Franz diffusion cells. LUV dispersions were exposed to the isotonic, hypotonic and hypertonic environment (difference of 300 mOsm/kg between the initial LUVs and the environment) and experimental data treated with both linear and non-linear (Korsmeyer-Peppas) regression models. To alter the rigidity of the liposomal membranes, cholesterol was introduced in the liposomal barriers (up to 25% w/w). Korsmeyer-Peppas model was proven to be suited to analyse experimental data throughout the experimental time frame, providing important additive information in comparison to standard linear approximation. The obtained results are highly relevant as they improve the interpretation of drug release kinetics from LUVs under osmotic stress. Moreover, the findings can be utilized in the development of liposomal formulations intended for nose-to-brain targeted drug delivery.

Advanced in silico modeling explains pharmacokinetics and biodistribution of temoporfin nanocrystals in humans

Foscan®, a formulation comprising temoporfin dissolved in a mixture of ethanol and propylene glycol, has been approved in Europe for palliative photodynamic therapy of squamous cell carcinoma of the head and neck. During clinical and preclinical studies it was observed that considering the administration route, the drug presents a rather atypical plasma profile as plasma concentration peaks delayed. Possible explanations, as for example the formation of a drug depot or aggregation after intravenous administration, are discussed in current literature. In the present study an advanced in silico model was developed and evaluated for the detailed description of Foscan® pharmacokinetics. Therefore, in vitro release data obtained from experiments with the dispersion releaser technology investigating dissolution pressures of various release media on the drug as well as in vivo data obtained from a clinical study were included into the in silico models. Furthermore, precipitation experiments were performed in presence of biorelevant media and precipitates were analyzed by nanoparticle tracking analysis. Size analysis and particle fraction were also incorporated in this model and a sensitivity analysis was performed. An optimal description of the in vivo situation based on in vitro release and particle characterization data was achieved, as demonstrated by an absolute average fold error of 1.21. This in vitro-in vivo correlation provides an explanation for the pharmacokinetics of Foscan® in humans.

Development and Characterization of Florfenicol-Loaded BSA Nanoparticles as Controlled Release Carrier

Florfenicol (FLO) is a broad-spectrum fluorinated antibiotic used for the treatment of bacterial diseases such as bovine respiratory disease (BRD) in cattle. FLO is a poorly soluble drug in aqueous solution, and its encapsulation in various nanovehicles has been reported to be less than 30%. In this context, the use of bovine serum albumin (BSA) as a nanocarrier for FLO is an interesting approach. BSA is a biocompatible, biodegradable, nontoxic, and nonimmunogenic natural protein, allowing the vehiculization of hydrophilic and hydrophobic drugs with a well-tolerated administration. The present work focuses on the fabrication and characterization of florfenicol-loaded BSA (FLO-BSA NPs), incorporation efficiency, and in vitro release pattern. FLO-BSA NPs nanoparticles were successfully obtained by a simple, low-cost and in a few steps method. The physicochemical properties of the obtained nanoparticles such as size (~ 120 nm), polydispersity index (0.04), and zeta potential (approximately - 40 mV) suggest a high colloidal stability and suitable characteristics for drug delivery. The drug loading reveals a high incorporation of florfenicol in the nanoparticles, in which 33.6 molecules of FLO are encapsulated per each molecule of BSA. The in vitro release profile exhibits an initial stage characterized by the burst effect and then a prolonged release of FLO from the albumin matrix, which is compatible with the Higuchi model and which follows a Fickian diffusion. The results together suggest a suitable tool for future investigations in drug delivery field in order to use this nanomaterial in food, pharmaceutical, and veterinary industry.