Toxicological assessment of nanoparticle interactions with the pulmonary system

Nanoparticle(NP)-based materials have breakthrough applications in many fields of life, such as in engineering, communications and textiles industries; food and bioenvironmental applications; medicines and cosmetics, etc. Biomedical applications of NPs are very active areas of research with successful translation to pharmaceutical and clinical uses overcoming both pharmaceutical and clinical challenges. Although the attractiveness and enhanced applications of these NPs stem from their exceptional properties at the nanoscale size, i.e. 1-1000 nm, they exhibit completely different physicochemical profiles and, subsequently, toxicological profiles from their parent bulk materials. Hence, the clinical evaluation and toxicological assessment of NPs interactions within biological systems are continuously evolving to ensure their safety at the nanoscale. The pulmonary system is one of the primary routes of exposure to airborne NPs either intentionally, via aerosolized nanomedicines targeting pulmonary pathologies such as cancer or asthma, or unintentionally, via natural NPs and anthropogenic (man-made) NPs. This review presents the state-of-the-art, contemporary challenges, and knowledge gaps in the toxicological assessment of NPs interactions with the pulmonary system. It highlights the main mechanisms of NP toxicity, factors influencing their toxicity, the different toxicological assessment methods and their drawbacks, and the recent NP regulatory guidelines based on literature collected from the research pool of NPs interactions with lung cell lines, in vivo inhalation studies, and clinical trials.

Fabrication and characterization of glimepiride nanosuspension by ultrasonication-assisted precipitation for improvement of oral bioavailability and in vitro α-glucosidase inhibition

Purpose

We aimed to enhance the solubility, dissolution rate, oral bioavailability, and α-glucosidase inhibition of glimepiride (Glm) by fabricating its nanosuspension using a precipitation-ultrasonication approach.

Methods

Glm nanosuspensions were fabricated using optimized processing conditions. Characterization of Glm was performed using Malvern Zetasizer, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry, and powder X-ray diffraction. Minimum particle size and polydispersity index (PDI) values were found to be 152.4±2.42 nm and 0.23±0.01, respectively, using hydroxypropyl methylcellulose: 6 cPs, 1% w/v, polyvinylpyrrolidone K30 1% w/v, and sodium lauryl sulfate 0.12% w/v, keeping ultrasonication power input at 400 W, with 15 minutes' processing at 3-second pauses. In vivo oral bioavailability was assessed using rabbits as a model.

Results

The saturation solubility of the Glm nanosuspensions was substantially enhanced 3.14-fold and 5.77-fold compared to unprocessed drug in stabilizer solution and unprocessed active pharmaceutical ingredient. Also, the dissolution rate of the nanosuspensions ws substantially boosted when compared to the marketed formulation and unprocessed drug candidate. The results showed that >85% of Glm nanosuspensions dissolved in the first 10 minutes compared to 10.17% of unprocessed Glm), 42.19% of microsuspensions, and 19.94% of marketed tablets. In-vivo studies conducted in animals, i.e. rabbits, demonstrated that maximum concentration and AUC_0-24 with oral dosing were twofold (5 mg/kg) and 1.74-fold (2.5 mg/kg) and 1.80-fold (5 mg/kg) and 1.63-fold (2.5 mg/kg), respectively, and compared with the unprocessed drug formulation. In-vitro α-glucosidase inhibition results showed that fabricated nanosuspensions had a pronounced effect compared to unprocessed drug.

Conclusion

The optimized batch fabricated by ultrasonication-assisted precipitation can be useful in boosting oral bioavailability, which may be accredited to enhanced solubility and dissolution rate of Glm, ultimately resulting in its faster rate of absorption due to nanonization.

Enhanced Oral Bioavailability of Celecoxib Nanocrystalline Solid Dispersion based on Wet Media Milling Technique: Formulation, Optimization and In Vitro/In Vivo Evaluation

Celecoxib (CLX), a selective COX-2 inhibitor, is a biopharmaceutics classification system (BCS) class II drug with its bioavailability being limited by thepoor aqueoussolubility. The purpose of this study was to develop and optimize CLX nanocrystalline(CLX-NC) solid dispersion prepared by the wet medium millingtechnique combined with lyophilizationto enhance oral bioavailability. In formulation screening, the resulting CLX-NC usingpolyvinylpyrrolidone (PVP) VA64 and sodiumdodecyl sulfate (SDS) as combined stabilizers showed the minimum particle size and a satisfactory stability. The formulation and preparation processwere further optimized by central composite experimentaldesign with PVP VA64 concentration (X₁), SDS concentration (X₂) and milling times (X₃) as independent factors and particle size (Y₁), polydispersity index (PDI, Y₂) and zeta potential (Y₃) as response variables. The optimal condition was determined as a combination of 0.75% PVP VA64, 0.11% SDS with milling for 90 min.The particle size, PDI and zeta potential of optimized CLX-NC were found to be 152.4 ± 1.4 nm, 0.191 ± 0.012 and −34.4 ± 0.6 mV, respectively. The optimized formulation showed homogeneous rod-like morphology as observed by scanning electron microscopy and was in a crystalline state as determined by differential scanning calorimetry and powder X-ray diffraction. In a storage stability study, optimized CLX-NC exhibited an excellent physical stability during six months’ storage at both the refrigeration and room conditions. In vivo pharmacokinetic research in Sprague-Dawley ratsdisplayed that C_max and AUC_0–∞ of CLX-NC were increased by 2.9 and 3.1 fold, compared with physical mixture. In this study, the screening and optimizing strategy of CLX-NC formulation represents a commercially viable approach forenhancing the oral bioavailability of CLX.

Bioavailability Enhancement of Poorly Soluble Drugs: The Holy Grail in Pharma Industry

Background:

Bioavailability, one of the prime pharmacokinetic properties of a drug, is defined as the fraction of an administered dose of unchanged drug that reaches the systemic circulation and is used to describe the systemic availability of a drug. Bioavailability assessment is imperative in order to demonstrate whether the drug attains the desirable systemic exposure for effective therapy. In recent years, bioavailability has become the subject of importance in drug discovery and development studies.

Methods:

A systematic literature review in the field of bioavailability and the approaches towards its enhancement have been comprehensively done, purely focusing upon recent papers. The data mining was performed using databases like PubMed, Science Direct and general Google searches and the collected data was exhaustively studied and summarized in a generalized manner.

Results:

The main prospect of this review was to generate a comprehensive one-stop summary of the numerous available approaches and their pharmaceutical applications in improving the stability concerns, physicochemical and mechanical properties of the poorly water-soluble drugs which directly or indirectly augment their bioavailability.

Conclusion:

The use of novel methods, including but not limited to, nano-based formulations, bio-enhancers, solid dispersions, lipid-and polymer-based formulations which provide a wide range of applications not only increases the solubility and permeability of the poorly bioavailable drugs but also improves their stability, and targeting efficacy. Although, these methods have drastically changed the pharmaceutical industry demand for the newer potential methods with better outcomes in the field of pharmaceutical science to formulate various dosage forms with adequate systemic availability and improved patient compliance, further research is required.

Activity and Cell-Death Pathway in Leishmania infantum Induced by Sugiol: Vectorization Using Yeast Cell Wall Particles Obtained From Saccharomyces cerevisiae

Visceral leishmaniasis, caused by Leishmania infantum, is a neglected tropical disease, to which efforts in the innovation of effective and affordable treatments remain limited, despite the rising incidence in several regions of the world. In this work, the antileishmanial effects of sugiol were investigated in vitro. This compound was isolated from the bark of Cupressus lusitanica and showed promising activity against L. infantum. In spite of the positive results, it is known that the compound is a poorly water-soluble diterpene molecule, which hinders further investigation, especially in preclinical animal studies. Thus, in an alternative delivery method, sugiol was entrapped in glucan-rich particles obtained from Saccharomyces cerevisiae yeast cell walls (YCWPs). To evaluate the activity of sugiol, the experiments were divided into two parts: (i) the in vitro investigation of antileishmanial activity of free sugiol against L. infantum promastigotes after 24, 48, and 72 h of treatment and (ii) the evaluation of antileishmanial activity of sugiol entrapped in glucan-rich particles against intracellular L. infantum amastigotes. Free sugiol induced the cell-death process in promastigotes, which was triggered by enhancing cytosolic calcium level and promoting the autophagy up to the first 24 h. Over time, the presence of autophagic vacuoles became rarer, especially after treatment with lower concentrations of sugiol, but other cellular events intensified, like ROS production, cell shrinkage, and phosphatidylserine exposure. Hyperpolarization of mitochondrial membrane potential was found at 72 h, induced by the mitochondria calcium uptake, causing an increase in ROS production and lipid peroxidation as a consequence. These events resulted in the cell death of promastigotes by secondary necrosis. Sugiol entrapped in glucan-rich particles was specifically recognized by dectin-1 receptor on the plasma membrane of macrophages, the main host cell of Leishmania spp. Electron micrographs revealed particles containing sugiol within the infected macrophages and these particles were active against the intracellular L. infantum amastigotes without affecting the host cell. Therefore, the YCWPs act like a Trojan horse to successfully deliver sugiol into the macrophage, presenting an interesting strategy to deliver water-insoluble drugs to parasitized cells.

Finding key nanoprecipitation variables for achieving uniform polymeric nanoparticles using neurofuzzy logic technology

Nanoprecipitation is a simple and fast method to produce polymeric nanoparticles (Np); however, most applications require filtration or another separation technique to isolate the nanosuspension from aggregates or polydisperse particle production. In order to avoid variability introduced by these additional steps, we report here a systematic study of the process to yield monomodal and uniform Np production with the nanoprecipitation method. To further identify key variables and their interactions, we used artificial neural networks (ANN) to investigate the multiple variables which influence the process. In this work, a polymethacrylate derivative was used for Np (NpERS) and a database with several formulations and conditions was developed for the ANN model. The resulting ANN model had a high predictability (> 70%) for NpERS characteristics measured (mean size, PDI, zeta potential, and number of particle populations). Moreover, the model identified production variables leading to polymer supersaturation, such as mixing time and turbulence, as key in achieving monomodal and uniform NpERS in one production step. Polymer concentration and type of solvent, modifiers of polymer diffusion and supersaturation, were also shown to control NpERS characteristics. The ANN study allowed the identification of key variables and their interactions and resulted in a predictive model to study the NpERS production by nanoprecipitation. In turn, we have achieved an optimized method to yield uniform NpERS which could pave way for polymeric nanoparticle production methods with potential in biological and drug delivery applications.

A comprehensive review on biological activities and toxicology of crocetin

Natural products with high pharmacological potential and low toxicity have been considered as the novel therapeutic agents. Crocetin is an active constituent of saffron (Crocus sativus L.) stigma, which in its free-acid form is insoluble in water and most organic solvents. Crocetin exhibits various health-promoting properties including anti-tumor, neuroprotective effects, anti-diabetics, anti-inflammatory, anti-hyperlipidemia, etc. These therapeutic effects can be achieved with different mechanisms such as improvement of oxygenation in hypoxic tissues, antioxidant effects, inhibition of pro-inflammatory mediators, anti-proliferative activity and stimulation of apoptosis in cancer cells. It is also worth considering that crocetin could be tolerated without major toxicity at therapeutic dosage in experimental models. In the present review, we discuss the biosynthesis, pharmacokinetic properties of crocetin and provide a comprehensive study on the biological activities and toxicity along with the mechanism of actions and clinical trials data of crocetin.

Mesoporous Silica Nanoparticles as a Prospective and Promising Approach for Drug Delivery and Biomedical Applications

Background:

With the development of nanotechnology, nanocarrier has widely been applied in such fields as drug delivery, diagnostic and medical imaging and engineering in recent years. Among all of the available nanocarriers, mesoporous silica nanoparticles (MSNs) have become a hot issue because of their unique properties, such as large surface area and voidage, tunable drug loading capacity and release kinetics, good biosafety and easily modified surface.

Objective:

We described the most recent progress in silica-assisted drug delivery and biomedical applications according to different types of Cargo in order to allow researchers to quickly learn about the advance in this field.

Methods:

Information has been collected from the recently published literature available mainly through Title or Abstract search in SpringerLink and PubMed database. Special emphasis is on the literature available during 2008-2017.

Results:

In this review, the major research advances of MSNs on the drug delivery and biomedical applications were summarized. The significant advantages of MSNs have also been listed. It was found that the several significant challenges need to be addressed and investigated to further advance the applications of these structurally defined nanomaterials.

Conclusion:

Through approaching this review, the researchers can be aware of many new synthetic methods, smart designs proposed in the recent year and remaining questions of MSNs at present.

Hybrid drug nanocrystals

Nanocrystals show promise to deliver poorly water-soluble drugs to yield systemic exposure. However, our knowledge regarding the in vivo fate of nanocrystals is in its infancy, as nanocrystallization is simply viewed as an approach to enhance the dissolution of drug crystals. The dying crystal phenomenon inspired the development of hybrid nanocrystals by physically embedding fluorophores into the crystal lattice. This approach achieved concurrent therapy and bioimaging and is well-established to study pharmacokinetics and nanocrystal dissolution in vivo. Nanocrystals also offer the advantage of long-term durability in the body for interacting with biological tissues and cells. This review introduces the hybrid nanocrystal technique, including the theoretical concepts, preparation, and applications. We also discuss the latest development in self-discriminative hybrid nanocrystals utilizing environment-responsive probes. This review will stimulate further development and application of nanocrystal-based drug delivery systems for theranostic strategies.

Drug nanocrystals: Fabrication methods and promising therapeutic applications

The drug nanocrystals (NCs) with unique physicochemical properties are now considered as a promising drug delivery system for poorly water-soluble drugs. So far >20 formulations of NCs have been approved in the market. In this review, we summarized recent advances of NCs with emphasis on their therapeutic applications based on administration route and disease states. At the end, we present a brief description of the future perspectives of NCs and their potential role as a promising drug delivery system. As a strategy for solubilization and bioavailability enhancement, the NCs have gained significant success. Besides this, the function of NCs is still far from developed. The emerging NC-based drug delivery approach would widen the applications of NCs in drug delivery and bio-medical field. Their in vitro and in vivo fate is extremely unclear; and the development of hybrid NCs with environment-sensitive fluorophores may assist to extend the scope of bio-imaging and provide better insight to their intracellular uptake kinetics, in vitro and in vivo.

Evaluation of improved oral bioavailability of ritonavir nanosuspension

The main objective of this study was to evaluate the pharmacokinetics of ritonavir (RTV) nanosuspension in rats in both fed and fasted state in comparison with coarse powder, physical mixture and commercial product (Norvir®). The point to point relation model was generated between the results of in vitro dissolution and in vivo pharmacokinetic studies. The oral RTV nanosuspension was prepared with microfluidization method. Nanosuspension was obtained with 540-550 nm of particle size, 0.1-0.4 of particle size distribution and about -20 mV of zeta potential values. According to in vivo pharmacokinetic studies in rats, C_max and AUC_0-t values in nanosuspension displayed an 8.9- and 12.5-fold increase compared to the coarse powder, and a 1.9- and 2.1-fold increase compared to the commercial product, respectively in the fed group. The point to point relation model showed that the correlation model was significant. It is concluded that nanosuspension is a promising drug delivery system to enhance oral bioavailability of ritonavir.

An Evaluation of Curcumin-Encapsulated Chitosan Nanoparticles for Transdermal Delivery

Curcumin-loaded chitosan nanoparticles were synthesised and evaluated in vitro for enhanced transdermal delivery. Zetasizer® characterisation of three different formulations of curcumin nanoparticles (Cu-NPs) showed the size ranged from 167.3 ± 3.8 nm to 251.5 ± 5.8 nm, the polydispersity index (PDI) values were between 0.26 and 0.46 and the zeta potential values were positive (+ 18.1 to + 20.2 mV). Scanning electron microscopy (SEM) images supported this size data and confirmed the spherical shape of the nanoparticles. All the formulations showed excellent entrapment efficiency above 80%. FTIR results demonstrate the interaction between chitosan and sodium tripolyphosphate (TPP) and confirm the presence of curcumin in the nanoparticle. Differential scanning calorimetry (DSC) studies of Cu-NPs indicate the presence of curcumin in a disordered crystalline or amorphous state, suggesting the interaction between the drug and the polymer. Drug release studies showed an improved drug release at pH 5.0 than in pH 7.4 and followed a zero order kinetics. The in vitro permeation studies through Strat-M® membrane demonstrated an enhanced permeation of Cu-NPs compared to aqueous curcumin solution (p ˂ 0.05) having a flux of 0.54 ± 0.03 μg cm^-2 h^-1 and 0.44 ± 0.03 μg cm^-2 h^-1 corresponding to formulations 5:1 and 3:1, respectively. The cytotoxicity assay on human keratinocyte (HaCat) cells showed enhanced percentage cell viability of Cu-NPs compared to curcumin solution. Cu-NPs developed in this study exhibit superior drug release and enhanced transdermal permeation of curcumin and superior percentage cell viability. Further ex vivo and in vivo evaluations will be conducted to support these findings.

Optimization of Extended-Release ZL-004 Nanosuspensions for In Vivo Pharmacokinetic Study to Enhance Low Solubility and Compliance

ZL-004, a promising small molecule that increases white blood cell counts, was developed for extended-release nanosuspensions to improve low solubility and compliance of patients. In vivo pharmacokinetic studies of nanosuspensions with different particle sizes and administration volumes were conducted. Unexpectedly, C_max of NS-PC-L (1156 nm) was 1.3 fold higher than NS-PB-L (836 nm), and area under plasma concentration-time curve (AUC) was similar. It suggested that in vivo behavior of nanosuspensions was influenced significantly by the original dissolved drug, which did not only rely on the particle size but also the amount of the free stabilizers. In addition, smaller administration volume (0.1 mL) achieved significantly lower C_max and AUC than the higher volume (0.5 mL), due to the reduced amount of dissolved drug. DSC and XPRD demonstrated that the crystal forms of nanosuspensions prepared by the precipitation method and high-pressure homogenization were similar; therefore, in vivo behaviors did not show significant differences. An additional 0.15% PEG 4000 enhanced the redispersity and maintained the particle size for 3 months. Finally, a nanosuspensions with the desired initial release was achieved, which lasted approximately 32 days steadily after a single dose. AUC and t_1/2 were 161.2 fold and 22.9 fold higher than oral administration.

A nanoparticle-based approach to improve the outcome of cancer active immunotherapy with lipopolysaccharides

This study sought to develop a simple nanoparticle-based approach to enhance the efficiency and tolerability of lipopolysaccharide (LPS), a potent ligand of Toll-like Receptor 4 (TLR4), for immunotherapy in cancer. Despite holding promise within this context, the strong pro-inflammatory properties of LPS also account for its low tolerability given localized and systemic side effects, which restrict the administrable dosage. Herein, we investigated the effect of LPS decoration as a surface-active molecule on a polymeric matrix upon its efficiency and tolerability. The LPS-decorated nanoparticles (LPS-NP) were about 150 nm in size, with slightly negative zeta potential (about -15 mV) and acceptable LPS incorporation (about 70%). In vitro, the particles accounted for a higher induction of apoptosis in tumor cells cultured with murine splenocytes compared to LPS solution. When used for the treatment of a murine syngeneic colorectal tumor model, higher intratumoral deposition of the particle-bound LPS was observed. Furthermore, unlike LPS solution, which accounted for localized necrosis at high concentrations, treatment of tumor-bearing animals with equivalent doses of LPS-NP was well tolerated. We propose that the observed localized necrosis can be Shwartzman phenomenon, which, due to modulated 24-h post-injection systemic TNF-α and LPS concentrations, have been avoided in case of LPS-NP. This has in turn enhanced the therapeutic efficiency and enabled complete tumor regression at concentrations at which LPS solution was intolerable. The findings indicate that nanoparticles can serve as beyond carriers for the delivery of superficially decorated LPS molecules, but impact their overall efficiency and tolerability in cancer therapy.

Enhanced dissolution of naproxen from pure-drug, crystalline nanoparticles: A case study formulated into spray-dried granules and compressed tablets

This is a case study of the use of rapidly-dissolving naproxen crystalline nanoparticles to prepare compressed tablets. The dissolution rates of different formulations were determined: the crystalline pure-drug nanodispersion, a pure-drug microsuspension, a granule prepared by spray drying the nanodispersion with mannitol, and a tablet prepared by compressing the granule with a bulking agent and a disintegrant. The goal was to determine the influence of each of the process steps on the rapid dissolution of the nanodispersion. A procedure was developed to allow sampling during the first 120 s of dissolution. Dissolution of the nanodispersion was completed after 60 s under both sink and non-sink conditions. Spray drying with mannitol delayed dissolution slightly under both sink and non-sink conditions. Under sink conditions a microsuspension (volume median size 11 µm) showed similar rapid dissolution to the nanodispersion. We propose this to be a result of rapid shrinkage of the microparticles on dissolution under sink conditions. This nullifies any effects of specific surface on dissolution rate. Under non-sink conditions the microparticles retain their lower specific surface for a longer time during dissolution and dissolve therefore more slowly. When compressed into tablets, the dissolution rates of nanoparticles or microparticles were determined primarily by the tablet disintegration time; the influence of sink or non-sink conditions was only observable after disintegration.

Amorphous Nanoparticulate Formulation of Sirolimus and Its Tablets

Nanocrystallization and amorphization have proven to be two effective strategies to improve the bioavailability of water-insoluble drugs. The purpose of our work was to develop a nano-formulated tablet of sirolimus (SRL) for enhanced dissolution. Amorphous SRL nanocomposites were prepared using anti-solvent precipitation via a high-gravity rotating packed bed. Various factors that affect particle size and size distribution, such as excipients, rotating speed, antisolvent/solvent flow rate, were investigated. Structure, stability and in vitro dissolution of the as-prepared SRL were evaluated. Furthermore, the nanoparticulated SRL tablet formula was screened to control drug release. Importantly, SRL tablets exhibit different dissolution profile by adjusting HPMC (hydroxypropyl methyl cellulose) content, which makes them more suitable for various formulation developments.

Plasmon Resonance of Silver Nanoparticles as a Method of Increasing Their Antibacterial Action

In this article, a series of silver-containing dressings are prepared by metal-vapor synthesis (MVS), and their antibacterial properties are investigated. The antibacterial activity of the dressings containing silver nanoparticles (AgNPs) against some Gram-positive, and Gram-negative microorganisms (Staphylococcus aureus, Staphylococcus haemolyticus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Moraxella spp.) has been determined. Based on the plasmon resonance frequency of these nanoparticles, the frequency of laser irradiation of the dressing was chosen. The gauze bandage examined showed pronounced antibacterial properties, especially to Staphylococcus aureus strain. When 470 nm laser radiation, with a power of 5 mW, was applied for 5 min, 4 h after inoculating the Petri dish, and placing a bandage containing silver nanoparticles on it, the antibacterial effect of the latter significantly increased—both against Gram-positive and Gram-negative microorganisms. The structure and chemical composition of the silver-containing nanocomposite were studied by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS). The synthesized AgNPs demonstrate narrow and monomodal particle size distribution with an average size of 1.75 nm. Atoms of metal in Ag/bandage system are mainly in Ag⁰ state, and the oxidized atoms are in the form of Ag-Ag-O groups.

Nanocrystals of Poorly Soluble Drugs: Drug Bioavailability and Physicochemical Stability

Many approaches have been developed over time to overcome the bioavailability limitations of poorly soluble drugs. With the advances in nanotechnology in recent decades, science and industry have been approaching this issue through the formulation of drugs as nanocrystals, which consist of “pure drugs and a minimum of surface active agents required for stabilization”. They are defined as “carrier-free submicron colloidal drug delivery systems with a mean particle size in the nanometer range, typically between 10–800 nm”. The primary importance of these nanoparticles was the reduction of particle size to nanoscale dimensions, with an increase in the particle surface area in contact with the dissolution medium, and thus in bioavailability. This approach has been proven successful, as demonstrated by the number of such drug products on the market. Nonetheless, despite the definition that indicates nanocrystals as a “carrier-free” system, surface active agents are necessary to prevent colloidal particles aggregation and thus improve stability. In addition, in more recent years, nanocrystal properties and technologies have attracted the interest of researchers as a means to obtain colloidal particles with modified biological properties, and thus their interest is now also addressed to modify the drug delivery and targeting. The present work provides an overview of the achievements in improving the bioavailability of poorly soluble drugs according to their administration route, describes the methods developed to overcome physicochemical and stability-related problems, and in particular reviews different stabilizers and surface agents that are able to modify the drug delivery and targeting.

Electrospun amorphous solid dispersions of poorly water-soluble drugs: A review

The development of oral dosage forms for poorly water-soluble active pharmaceutical ingredients (APIs) is a persistent challenge. A range of methods has been explored to address this issue, and amorphous solid dispersions (ASDs) have received increasing attention. ASDs are typically prepared by starting with a liquid precursor (a solution or melt) and applying energy for solidification. Many techniques can be used, with the emergence of electrospinning as a potent option in recent years. This method uses electrical energy to induce changes from liquid to solid. Through the direct applications of electrical energy, electrospinning can generate nanofiber-based ASDs from drug-loaded solutions, melts and melt-solutions. The technique can also be combined with other approaches using the application of mechanical, thermal or other energy sources. Electrospinning has numerous advantages over other approaches to produce ASDs. These advantages include extremely rapid drying speeds, ease of implentation, compatibility with a wide range of active ingredients (including those which are thermally labile), and the generation of products with large surface areas and high porosity. Furthermore, this technique exhibits the potential to create so-called 'fifth-generation' ASDs with nanostructured architectures, such as core/shell or Janus systems and their combinations. These advanced systems can improve dissolution behaviour and provide programmable drug release profiles. Additionally, the fiber components and their spatial distributions can be precisely controlled. Electrospun fiber-based ASDs can maintain an incorporated active ingredient in the amorphous physical form for prolonged periods of time because of their homogeneous drug distribution within the polymer matrix (typically they comprise solid solutions), and ability to inhibit molecular motion. These ASDs can be utilised to generate oral dosage forms for poorly water-soluble drugs, resulting in linear or multiple-phase release of one or more APIs. Electrospun ASDs can also be exploited as templates for manipulating molecular self-assembly, offering a bridge between ASDs and other types of dosage forms. This review addresses the development, advantages and pharmaceutical applications of electrospinning for producing polymeric ASDs. Material preparation and analysis procedures are considered. The mechanisms through which performance has been improved are also discussed.

Formulation and Molecular Dynamics Simulations of a Fusidic Acid Nanosuspension for Simultaneously Enhancing Solubility and Antibacterial Activity

The aim of the present study was to formulate a nanosuspension (FA-NS) of fusidic acid (FA) to enhance its aqueous solubility and antibacterial activity. The nanosuspension was characterized using various in vitro, in silico, and in vivo techniques. The size, polydispersity index, and zeta potential of the optimized FA-NS were 265 ± 2.25 nm, 0.158 ± 0.026, and -16.9 ± 0.794 mV, respectively. The molecular dynamics simulation of FA and Poloxamer-188 showed an interaction and binding energy of -74.42 kJ/mol and -49.764 ± 1.298 kJ/mol, respectively, with van der Waals interactions playing a major role in the spontaneous binding. There was an 8-fold increase in the solubility of FA in a nanosuspension compared to the bare drug. The MTT assays showed a cell viability of 75-100% confirming the nontoxic nature of FA-NS. In vitro antibacterial activity revealed a 16- and 18-fold enhanced activity against Staphylococcus aureus (SA) and methicillin-resistant SA (MRSA), respectively, when compared to bare FA. Flowcytometry showed that MRSA cells treated with FA-NS had almost twice the percentage of dead bacteria in the population, despite having an 8-fold lower MIC in comparison to the bare drug. The in vivo skin-infected mice showed a 76-fold reduction in the MRSA load for the FA-NS treated group compared to that of the bare FA. These results show that the nanosuspension of antibiotics can enhance their solubility and antibacterial activity simultaneously.

Application of the solubility parameter concept to assist with oral delivery of poorly water-soluble drugs – a PEARRL review

Objectives

Solubility parameters have been used for decades in various scientific fields including pharmaceutics. It is, however, still a field of active research both on a conceptual and experimental level. This work addresses the need to review solubility parameter applications in pharmaceutics of poorly water-soluble drugs.

Key findings

An overview of the different experimental and calculation methods to determine solubility parameters is provided, which covers from classical to modern approaches. In the pharmaceutical field, solubility parameters are primarily used to guide organic solvent selection, cocrystals and salt screening, lipid-based delivery, solid dispersions and nano- or microparticulate drug delivery systems. Solubility parameters have been applied for a quantitative assessment of mixtures, or they are simply used to rank excipients for a given drug.

Summary

In particular, partial solubility parameters hold great promise for aiding the development of poorly soluble drug delivery systems. This is particularly true in early-stage development, where compound availability and resources are limited. The experimental determination of solubility parameters has its merits despite being rather labour-intensive because further data can be used to continuously improve in silico predictions. Such improvements will ensure that solubility parameters will also in future guide scientists in finding suitable drug formulations.

Core-shell nanoparticles for targeted and combination antiretroviral activity in gut-homing T cells

A major sanctuary site for HIV infection is the gut-associated lymphoid tissue (GALT). The α4β7 integrin gut homing receptor is a promising therapeutic target for the virus reservoir because it leads to migration of infected cells to the GALT and facilitates HIV infection. Here, we developed a core-shell nanoparticle incorporating the α4β7 monoclonal antibody (mAb) as a dual-functional ligand for selectively targeting a protease inhibitor (PI) to gut-homing T cells in the GALT while simultaneously blocking HIV infection. Our nanoparticles significantly reduced cytotoxicity of the PI and enhanced its in vitro antiviral activity in combination with α4β7 mAb. We demonstrate targeting function of our nanocarriers in a human T cell line and primary cells isolated from macaque ileum, and observed higher in vivo biodistribution to the murine small intestines where they accumulate in α4β7+ cells. Our LCNP shows the potential to co-deliver ARVs and mAbs for eradicating HIV reservoirs.

Design and characterization of loratadine nanosuspension prepared by ultrasonic-assisted precipitation

Nanoparticle engineering is a well-defined technique employed as a novel and effective method in drug design and delivery. It is widely used to control particle size, as well as the morphological and physicochemical properties of active pharmaceutical ingredients. Furthermore, it serves as a method of pre-dispersion preparation for various dosage form developments. Nanotechnology produces nanomaterials with enhanced properties in terms of solubility, dissolution and permeability. In this work, ultrasonic-assisted precipitation was employed to produce nanosuspensions of poorly water-soluble loratadine, using different stabilizers. The objective of our study was attempting to prepare solid nanoparticles of loratadine to be used as a possible intermediate for designing various dosage forms. The effects of the type(s) and concentration(s) of stabilizer(s) on mean particle size were assessed. Optimal process parameters required to produce homogeneous nanoparticles with particle size below 500 nm and polydispersity less than 0.3 were determined both for precipitation and ultrasonication. Pre-dispersions were evaluated for their particle size, polydispersity index and zeta potential. Freeze-drying was employed to produce dry nanoparticles. Particle size, particle size distribution and zeta potential of the dried nanoparticles were measured after reconstitution in water. Besides thermal analysis using DSC and structural analyses (XRPD and FT-IR), the morphological characteristics and dissolution behaviors were also investigated. The selected freeze-dried nanoparticles had a mean particle size range of 353-441 nm, a polydispersity index ranging between 0.167 and 0.229 and a zeta potential between -25.7 and -20.7 mV. These results suggest that material and process parameters were successfully optimized. DSC and XRPD spectra confirmed interactions between the formulation's components during freeze-drying. The solid nanoparticles showed 30-42% of cumulative release after 10 min compared to less than 1% of dissolution characterizing loratadine without pre-processing. This study demonstrates that preparing dried loratadine nanoparticles suitable for designing effective drug preparations is a feasible approach.

Long acting systemic HIV pre-exposure prophylaxis: an examination of the field

Oral pre-exposure prophylaxis for the prevention of HIV-1 transmission (HIV PrEP) has been widely successful as demonstrated by a number of clinical trials. However, studies have also demonstrated the need for patients to tightly adhere to oral dosing regimens in order to maintain protective plasma and tissue concentrations. This is especially true for women, who experience less forgiveness from dose skipping than men in clinical trials of HIV PrEP. There is increasing interest in long-acting (LA), user-independent forms of HIV PrEP that could overcome this adherence challenge. These technologies have taken multiple forms including LA injectables and implantables. Phase III efficacy trials are ongoing for a LA injectable candidate for HIV PrEP. This review will focus on the design considerations for both LA injectable and implantable platforms for HIV PrEP. Additionally, we have summarized the existing LA technologies currently in clinical and pre-clinical studies for HIV PrEP as well as other technologies that have been applied to HIV PrEP and contraceptives. Our discussion will focus on the potential application of these technologies in low resource areas, and their use in global women's health.

Modifications of quinolones and fluoroquinolones: hybrid compounds and dual-action molecules

ABSTRACT

This review is aimed to provide extensive survey of quinolones and fluoroquinolones for a variety of applications ranging from metal complexes and nanoparticle development to hybrid conjugates with therapeutic uses. The review covers the literature from the past 10 years with emphasis placed on new applications and mechanisms of pharmacological action of quinolone derivatives. The following are considered: metal complexes, nanoparticles and nanodrugs, polymers, proteins and peptides, NO donors and analogs, anionic compounds, siderophores, phosphonates, and prodrugs with enhanced lipophilicity, phototherapeutics, fluorescent compounds, triazoles, hybrid drugs, bis-quinolones, and other modifications. This review provides a comprehensive resource, summarizing a broad range of important quinolone applications with great utility as a resource concerning both chemical modifications and also novel hybrid bifunctional therapeutic agents.

GRAPHICAL ABSTRACT

Production of pure drug nanocrystals and nano co-crystals by confinement methods

The use of drug nanocrystals in the drug formulation is increasing due to the large number of poorly water-soluble drug compounds synthetized and due to the advantages brought by the nanonization process. The downsizing processes are done using a top-down approach (milling and homogenization currently employed at the industrial level), while the crystallization process is performed by bottom-up techniques (e.g., antisolvent precipitation, use of supercritical fluids or spray and freeze drying). In addition, the production of nanocrystals in confined environment can be achieved within microfluidics channels. This review analyzes the processes for the preparation of nanocrystals and co-crystals, divided by top-down and bottom-up approaches, together with their combinations. The combination of both strategies merges the favorable features of each process and avoids the disadvantages of single processes. Overall, the applicability of drug nanocrystals is highlighted by the widespread research on the production processes at the engineering, pharmaceutical, and nanotechnology level.

Tablets made from paper

The possibility to compress ordinary paper into tablets was systematically investigated in this study. Results proved that tablets can be made from paper, independent of the type of paper used. The tablets appear shiny and with a smooth surface. The pharmaceutical quality was acceptable, i.e. all tablets fulfilled the requirements for tablets according to the European Pharmacopeia. Drug-loaded tablets were produced by compression of drug-loaded paper. Drug loading did not alter the pharmaceutical quality. However, the uncoated tablets possessed an extremely fast disintegration, i.e. intense swelling upon contact with water, which might hamper the swallowing after oral administration. To avoid swelling tablets were successfully coated with a polymer film, leading to a prevention of swelling but immediate disintegration in simulated gastric fluid. In fact, tablets made from paper are a novel and promising strategy for improved oral drug delivery. They can be easily produced without any further excipients and possess pharmaceutical quality according to the European Pharmacopeia.

Supercritical carbon dioxide-based technologies for the production of drug nanoparticles/nanocrystals - A comprehensive review

Low drug bioavailability, which is mostly a result of poor aqueous drug solubilities and of inadequate drug dissolution rates, is one of the most significant challenges that pharmaceutical companies are currently facing, since this may limit the therapeutic efficacy of marketed drugs, or even result in the discard of potential highly effective drug candidates during developmental stages. Two of the main approaches that have been implemented in recent years to overcome poor drug solubility/dissolution issues have frequently involved drug particle size reduction (i.e., micronization/nanonization) and/or the modification of some of the physicochemical and structural properties of poorly water soluble drugs. A large number of particle engineering methodologies have been developed, tested, and applied in the synthesis and control of particle size/particle-size distributions, crystallinities, and polymorphic purities of drug micro- and nano-particles/crystals. In recent years pharmaceutical processing using supercritical fluids (SCF), in general, and supercritical carbon dioxide (scCO₂), in particular, have attracted a great attention from the pharmaceutical industry. This is mostly due to the several well-known advantageous technical features of these processes, as well as to other increasingly important subjects for the pharmaceutical industry, namely their "green", sustainable, safe and "environmentally-friendly" intrinsic characteristics. In this work, it is presented a comprehensive state-of-the-art review on scCO₂-based processes focused on the formation and on the control of the physicochemical, structural and morphological properties of amorphous/crystalline pure drug nanoparticles. It is presented and discussed the most relevant scCO₂, scCO₂-based fluids and drug physicochemical properties that are pertinent for the development of successful pharmaceutical products, namely those that are critical in the selection of an adequate scCO₂-based method to produce pure drug nanoparticles/nanocrystals. scCO₂-based nanoparticle formation methodologies are classified in three main families, and in terms of the most important role played by scCO₂ in particle formation processes: as a solvent; as an antisolvent or a co-antisolvent; and as a "high mobility" additive (a solute, a co-solute, or a co-solvent). Specific particle formation methods belonging to each one of these families are presented, discussed and compared. Some selected amorphous/crystalline drug nanoparticles that were prepared by these methods are compiled and presented, namely those studied in the last 10-15 years. A special emphasis is given to the formation of drug cocrystals. It is also discussed the fundamental knowledge and the main mechanisms in which the scCO₂-based particle formation methods rely on, as well as the current status and urgent needs in terms of reliable experimental data and of robust modeling approaches. Other addressed and discussed topics include the currently available and the most adequate physicochemical, morphological and biological characterization methods required for pure drug nanoparticles/nanocrystals, some of the current nanometrology and regulatory issues associated to the use of these methods, as well as some scale-up, post-processing and pharmaceutical regulatory subjects related to the industrial implementation of these scCO₂-based processes. Finally, it is also discussed the current status of these techniques, as well as their future major perspectives and opportunities for industrial implementation in the upcoming years.

Unified Scaling of the Structure and Loading of Nanoparticles Formed by Diffusion-Limited Coalescence

The present study establishes the scaling laws describing the structure of spherical nanoparticles formed by diffusion-limited coalescence. We produced drug-loaded nanoparticles from a poly(ethylene glycol)-poly(d,l-lactic acid) diblock polymer (PEG- b-PLA) by the nanoprecipitation method using different types of micromixing chambers to explore multiple mixing regimes and characteristic times. We first show that the drug loading of the nanoparticles is not controlled by the mixing time but solely by the drug-to-polymer ratio (D:P) in the feed and the hydrophobicity of the drug scaled via the partition coefficient P. We then procure compelling evidence that particles formed via diffusion/coalescence exhibit a relative distribution of PEG blocks between the particle core and its shell that depends only on mixing conditions (not on D:P). Scaling laws of PEG relative distribution and chain surface density were derived in different mixing regimes and showed excellent agreement with experimental data. In particular, results made evident that PEG blocks entrapment in the core of the particles occurs in the slow-mixing regime and favors the overloading (above the thermodynamic limit) of the particles with hydrophilic drugs. The present analysis compiles effective guidelines for the scale up of nanoparticles structure and properties with mixing conditions, which should facilitate their future translation to medical and industrial settings.

How to measure release from nanosized carriers?

Novel drug delivery systems exhibit great potential in the formulation of poorly soluble compounds but have also been applied to reduce side effects of highly active drug molecules. Despite all efforts, there are only few technologies available to investigate the in vitro release of next-generation nanotherapeutics. In the following, different approaches for testing the drug release from nanoparticles in the fields of formulation development and quality control will be discussed. A variety of methods is available, starting from dialysis-based equipment, in situ measurements, flow-through devices and sample and separate setups. If possible, these methods should enable a more rapid formulation development and quality control of nanosized carriers as well as improve the prediction of in vivo performance and clinical outcomes.

Multi-faceted Characterization of Wet-milled Griseofulvin Nanosuspensions for Elucidation of Aggregation State and Stabilization Mechanisms

Characterization of wet-milled drug suspensions containing neutral polymer-anionic surfactant as stabilizers poses unique challenges in terms of assessing the aggregation state and examining the stabilization mechanisms. Using a multi-faceted characterization method, this study aims to assess the aggregation state of wet-milled griseofulvin (GF) nanosuspensions and elucidate the stabilization mechanisms and impact of stabilizers. Two grades, SSL and L, of hydroxypropyl cellulose (HPC) with molecular weights of 40 and 140 kg/mol, respectively, were used as a neutral stabilizer at concentrations varying from 0 to 7.5% (w/w) without and with 0.05% (w/w) sodium dodecyl sulfate (SDS). The aggregation state was examined via laser diffraction, scanning electron microscope (SEM) imaging, and rheometry. Zeta potential, stabilizer adsorption, surface tension, and drug wettability were used to elucidate the stabilization mechanisms. The results suggest that deviation from a uni-modal PSD and pronounced pseudoplasticity with power-law index lower than one signify severe aggregation. Polymer or surfactant alone was not able to prevent GF nanoparticle aggregation, whereas HPC-SDS combination led to synergistic stabilization. The effect of polymer concentration was explained mainly by the stabilizer adsorption and partly by surface tension. The synergistic stabilization afforded by HPC-SDS, traditionally explained by electrosteric mechanism, was attributed to steric stabilization provided by HPC and enhanced GF wettability/reduced surface tension provided by SDS. Zeta potential results could not explain the mitigation of aggregation by HPC-SDS. Overall, this study has demonstrated that the elucidation of the complex effects of HPC-SDS on GF nanosuspension stability entails a multi-faceted and comprehensive characterization approach.

Acoustically enhanced microfluidic mixer to synthesize highly uniform nanodrugs without the addition of stabilizers

Background

This article presents an acoustically enhanced microfluidic mixer to generate highly uniform and ultra-fine nanoparticles, offering significant advantages over conventional liquid antisolvent techniques.

Methods

The method employed a 3D microfluidic geometry whereby two different phases – solvent and antisolvent – were introduced at either side of a 1 μm thick resonating membrane, which contained a through-hole. The vibration of the membrane rapidly and efficiently mixed the two phases, at the location of the hole, leading to the formation of nanoparticles.

Results

The versatility of the device was demonstrated by synthesizing budesonide (a common asthma drug) with a mean diameter of 135.7 nm and a polydispersity index of 0.044.

Conclusion

The method offers a 40-fold reduction in the size of synthesized particles combined with a substantial improvement in uniformity, achieved without the need of stabilizers.

Production and characterization of vitamin D3 loaded starch nanoparticles: effect of amylose to amylopectin ratio and sonication parameters

Two types of starches with different amylose to amylopectin ratios were used for the production of vitamin D₃ loaded nanoparticles and effects of starch type, sonication time and temperature on physicochemical properties of nanocarriers were investigated. Both high amylose corn and potato starches nanocarriers had granular structure with particle size ranging from 32.04 to 99.2 nm and the encapsulation efficiency ranging from 22.34 to 94.8%. The results showed that potato starch nanoparticles had larger size, higher zeta potential, encapsulation efficiency and encapsulation load and lower polydispersity index values in comparison to high amylose corn starch nanoparticle. Increase in sonication time reduced the size of nanoparticles in both starch types and decreasing temperature led to reduction of particle size and increase of zeta potential. Physicochemical features of nanocarriers were analyzed by Fourier transform-infrared spectroscopy, X-ray diffraction and differential scanning calorimetry. The results indicated that vitamin D₃ is well incorporated in carriers and ultrasonic treatment led to increase of hydrocarbon chain that resulted in van der Waals and hydrogen bonds of vitamin D₃ with the potato starch and greater thermal stability.

Improved delivery of poorly soluble compounds using nanoparticle technology: a review

Although a large number of new drug molecules with varied therapeutic potentials have been discovered in the recent decade, yet most of them are still in developmental process. This can be attributed to the limited aqueous solubility which governs the bioavailability of such drug molecules. Hence, there is a requisite for a technology-based product (formulation) in order to overcome such issues without compromising on the therapeutic response. The purpose of this review is to provide an insight to the formulation of drug nanoparticles for enhancing solubility and dissolution velocity with concomitant enhancement in bioavailability. In the recent decade, nanonization has evolved from a concept to reality owing to its versatile applications, especially in the development of drugs having poor solubility. In this review, a relatively simple and scalable approach for the manufacture of drug nanoparticles and latest characterization techniques utilized to evaluate the drug nanoparticles are discussed. The drug nanoparticulate approach described herein provides a general applicability of the platform technology in designing a formulation for drugs associated with poor aqueous solubility.