Facile Preparation of Danazol Nanoparticles by High-Gravity Anti-solvent Precipitation (HGAP) Method

Recent developments in the use of nanocrystals to improve bioavailability of APIs

Nanocrystals refer to materials with at least one dimension smaller than 100 nm, composing of atoms arranged in single crystals or polycrystals. Nanocrystals have significant research value as they offer unique advantages over conventional pharmaceutical formulations, such as high bioavailability, enhanced targeting selectivity and controlled release ability and are therefore suitable for the delivery of a wide range of drugs such as insoluble drugs, antitumor drugs and genetic drugs with broad application prospects. In recent years, research on nanocrystals has been progressively refined and new products have been launched or entered the clinical phase of studies. However, issues such as safety and stability still stand that need to be addressed for further development of nanocrystal formulations, and significant gaps do exist in research in various fields in this pharmaceutical arena. This paper presents a systematic overview of the advanced development of nanocrystals, ranging from the preparation approaches of nanocrystals with which the bioavailability of poorly water-soluble drugs is improved, critical properties of nanocrystals and associated characterization techniques, the recent development of nanocrystals with different administration routes, the advantages and associated limitations of nanocrystal formulations, the mechanisms of physical instability, and the enhanced dissolution performance, to the future perspectives, with a final view to shed more light on the future development of nanocrystals as a means of optimizing the bioavailability of drug candidates. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Nanonized carbamazepine for nose-to-brain delivery: pharmaceutical formulation development

Epilepsy is one of the most common neurological disorders in the world. The therapeutic treatment is challenging since conventional drugs have limited efficacy and several side effects that impair patient management. Efforts are being made to find innovative strategies to control epileptic seizures. Intranasal administration provides a convenient route to deliver the drug to the brain. Carbamazepine (CBZ) is an anticonvulsant characterized by poor water solubility, nanonization can improve its bioavailability. Therefore, the design of CBZ nanocrystals (NCs) was assessed to obtain a formulation suitable for nose-to-brain delivery. CBZ NCs were prepared by sonoprecipitation following the Quality by Design approach identifying the impact of process and formulation variables on the critical quality attributes of the final product. The formulation was characterized by a technological point of view (thermotropic behavior, crystallinity, morphology, mucoadhesive strength). Response surface methodology was a reliable tool (error % 2.6) to optimize CBZ NCs with size ≤300 nm. Incubation of CBZ NCs in artificial cerebrospinal fluid at 37 °C did not promote aggregation and degradation phenomena. Preliminary biological studies revealed the biocompatibility of CBZ NCs towards Olfactory Ensheating Cells. The suspension was successfully converted into a powder. The highly concentrated formulation can be obtained, providing the possibility to administer the maximum dose of the drug in the lowest volume.

Production and isolation of pharmaceutical drug nanoparticles

Nanosizing of pharmaceutical drug particles is one of the most important drug delivery platforms approaches for the commercial development of poorly water-soluble drug molecules. Though nanosizing of drug particles has been proven to greatly enhance drugs dissolution rate and apparent solubility, nanosized materials have presented significant challenges for their formulation as solid dosage forms (e.g. tablets, capsules). This is due to the strong Van der Waals attraction forces between dry nanoparticles leading to aggregation, cohesion, and consequently poor flowability. In this review, the broad area of nanomedicines is overviewed with the primary focus on drug nanocrystals and the top-down and bottom-up methods used in their fabrication. The review also looks at how nanosuspensions of pharmaceutical drugs are generated and stabilised, followed by subsequent strategies for isolation of the nanoparticles. A perspective on the future outlook for drug nanocrystals is also presented.

Characterization and Functional Test of Canine Probiotics

Probiotics can modulate the composition of gut microbiota and benefit the host animal health in multiple ways. Lactic acid bacteria (LAB), mainly Lactobacillus and Bifidobacterium species, are well-known microbes with probiotic potential. In the present study, 88 microbial strains were isolated from canine feces and annotated. Among these, the four strains CACC517, 537, 558, and 566 were tested for probiotic characteristics, and their beneficial effects on hosts were evaluated both in vitro and in vivo; these strains exhibited antibiosis, antibiotic activity, acid and bile tolerance, and relative cell adhesion to the HT-29 monolayer cell line. Byproducts of these strains increased the viability and decreased oxidative stress in mouse and dog cell lines (RAW264.7 and DH82, respectively). Subsequently, when the probiotics were applied to the clinical trial, changes in microbial composition and relative abundance of bacterial strains were clearly observed in the experimental animals. Experimental groups before and after the application were obviously separated from PCA analysis of clinical results. Conclusively, these results could provide comprehensive understanding of the effects of probiotic strains (CACC517, 537, 558, and 566) and their industrial applications.

Empirical Modelling of Hydrodynamic Effects on Starch Nanoparticles Precipitation in a Spinning Disc Reactor

Empirical correlations have been developed to relate experimentally determined starch nanoparticle size obtained in a solvent–antisolvent precipitation process with key hydrodynamic parameters of a spinning disc reactor (SDR). Three different combinations of dimensionless groups including a conventional Reynolds number (Re), rotational Reynolds number (Re_ω) and Rossby number (Ro) have been applied in individual models for two disc surfaces (smooth and grooved) to represent operating variables affecting film flow such as liquid flowrate and disc rotational speed, whilst initial supersaturation (S) has been included to represent varying antisolvent concentrations. Model 1 featuring a combination of Re, Re_ω and S shows good agreement with the experimental data for both the grooved and smooth discs. For the grooved disc, Re has a greater impact on particle size, whereas Re_ω is more influential on the smooth disc surface, the difference likely being due to the passive mixing induced by the grooves irrespective of the magnitude of the disc speed. Supersaturation has little impact on particle size within the limited initial supersaturation range studied. Model 2 which characterises both flow rate and disc rotational speed through Ro alone and combined with Re was less accurate in predicting particle size due to several inherent limitations.

Comparative genomics of canine Lactobacillus reuteri reveals adaptation to a shared environment with humans

BACKGROUND

Lactobacillus reuteri is a gram-positive, non-motile bacterial species that has been used as a representative microorganism model to describe the ecology and evolution of vertebrate gut symbionts.

OBJECTIVE

Because the genetic features and evolutionary strategies of L. reuteri from the gastrointestinal tract of canines remain unknown, we tried to construct draft genome canine L. reuteri and investigate modified, acquired, or lost genetic features that have facilitated the evolution and adaptation of strains to specific environmental niches by this study.

METHODS

To examine canine L. reuteri, we sequenced an L. reuteri strain isolated from a dog in Korea. A comparative genomic approach was used to assess genetic diversity and gain insight into the distinguishing features related to different hosts based on 27 published genomic sequences.

RESULTS

The pan-genome of 28 L. reuteri strains contained 7,369 gene families, and the core genome contained 1070 gene families. The ANI tree based on the core genes in the canine L. reuteri strain (C1) was very close to those for three strains (IRT, DSM20016, JCM1112) from humans. Evolutionarily, these four strains formed one clade, which we regarded as C1-clade in this study. We could investigate a total of 32,050 amino acid substitutions among the 28 L. reuteri strain genomes. In this comparison, 283 amino acid substitutions were specific to strain C1 and four strains in C1-clade shared most of these 283 C1-strain specific amino acid substitutions, suggesting strongly similar selective pressure. In accessory genes, we could identify 127 C1-clade host-specific genes and found that several genes were closely related to replication, recombination, and repair.

CONCLUSION

This study provides new insights into the adaptation of L. reuteri to the canine intestinal habitat, and suggests that the genome of L. reuteri from canines is closely associated with their living and shared environment with humans.

An Aseptic One-Shot Bottom-Up Method To Produce Progesterone Nanocrystals: Controlled Size and Improved Bioavailability

Progesterone (PG) is an essential sex hormone with a variety of important biological functions, but its insolubility leads to low bioavailability of most water-based formulations. What is more, the commercial oil-based formulations often cause severe side effects after long-term injection due to poor tissue absorption of oil. Herein, we report an aseptic bottom-up method utilizing emulsion freeze-drying technology that produces size-controllable, highly bioavailable, and water-based PG nanocrystal injection. The key factors that can determine the features of nanocrystals were investigated, including solvents, water-to-oil ratio, drug concentrations, type of surfactants, temperature in freeze-drying process, and lyoprotectants. Mechanisms of crystal growth formation process for PG nanocrystals were also analyzed theoretically. The prepared water-based PG nanocrystal suspension injection (PG/NSI) not only showed quick dissolution behaviors but also had significantly improved bioavailability in vivo. Therefore, this method can effectively control the size of nanocrystals, enhance bioavailability of insoluble drugs, and produce aseptic water-based nanocrystals that can be directly used for injection. Moreover, this method can also be used to prepare nanocrystals with the desired size under aseptic conditions for other poorly water-soluble drugs.

Research progress in materials-oriented chemical engineering in China

Materials-oriented chemical engineering involves the intersection of materials science and chemical engineering. Development of materials-oriented chemical engineering not only contributes to material research and industrialization techniques but also opens new avenues for chemical engineering science. This review details the major achievements of materials-oriented chemical engineering fields in China, including preparation strategies for advanced materials based on the principles of chemical engineering as well as innovative separation and reaction techniques determined by new materials. Representative industrial applications are also illustrated, highlighting recent advances in the field of materials-oriented chemical engineering technologies. In addition, we also look at the ongoing trends in materials-oriented chemical engineering in China.

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.

Nanosizing techniques for improving bioavailability of drugs

The poor solubility of significant number of Active Pharmaceutical Ingredients (APIs) has become a major challenge in the drug development process. Drugs with poor solubility are difficult to formulate by conventional methods and often show poor bioavailability. In the last decade, attention has been focused on developing nanocrystals for poorly water soluble drugs using nanosizing techniques. Nanosizing is a pharmaceutical process that changes the size of a drug to the sub-micron range in an attempt to increase its surface area and consequently its dissolution rate and bioavailability. The effectiveness of nanocrystal drugs is evidenced by the fact that six FDA approved nanocrystal drugs are already on the market. The bioavailabilities of these preparations have been significantly improved compared to their conventional dosage forms. There are two main approaches for preparation of drug nanocrystals; these are the top-down and bottom-up techniques. Top-down techniques have been successfully used in both lab scale and commercial scale manufacture. Bottom-up approaches have not yet been used at a commercial level, however, these techniques have been found to produce narrow sized distribution nanocrystals using simple methods. Bottom-up techniques have been also used in combination with top-down processes to produce drug nanoparticles. The main aim of this review article is to discuss the various methods for nanosizing drugs to improve their bioavailabilities.

Recent advances in the engineering of nanosized active pharmaceutical ingredients: Promises and challenges

The advances in the field of nanotechnology have revolutionized the field of delivery of poorly soluble active pharmaceutical ingredients (APIs). Nanosized formulations have been extensively investigated to achieve a rapid dissolution and therefore pharmacokinetic properties similar to those observed in solutions. The present review outlines the recent advances, promises and challenges of the engineering nanosized APIs. The principles, merits, demerits and applications of the current 'bottom-up' and 'top-down' technologies by which the state of the art nanosized APIs can be produced were described. Although the number of research reports on the nanoparticle engineering topic has been growing in the last decade, the challenge is to take numerous research outcomes and convert them into strategies for the development of marketable products.

Development and evaluation of transferrin-stabilized paclitaxel nanocrystal formulation

The aim of the present study was to prepare and evaluate a paclitaxel nanocrystal-based formulation stabilized by serum protein transferrin in a non-covalent manner. The pure paclitaxel nanocrystals were first prepared using an antisolvent precipitation method augmented by sonication. The serum protein transferrin was selected for use after evaluating the stabilizing effect of several serum proteins including albumin and immunoglobulin G. The formulation contained approximately 55-60% drug and was stable for at least 3months at 4°C. In vivo antitumor efficacy studies using mice inoculated with KB cells demonstrate significantly higher tumor inhibition rate of 45.1% for paclitaxel-transferrin formulation compared to 28.8% for paclitaxel nanosuspension treatment alone. Interestingly, the Taxol(®) formulation showed higher antitumor activity than the paclitaxel-transferrin formulation, achieving a 93.3% tumor inhibition rate 12days post initial dosing. However, the paclitaxel-transferrin formulation showed a lower level of toxicity, which is indicated by a steady increase in body weight of mice over the treatment period. In comparison, treatment with Taxol(®) resulted in toxicity issues as body weight decreased. These results suggest the potential benefit of using a serum protein in a non-covalent manner in conjunction with paclitaxel nanocrystals as a promising drug delivery model for anticancer therapy.

Binary VOCs absorption in a rotating packed bed with blade packings

This investigation addressed the mass transfer of rotating packed beds with blade packings in removing methanol and 1-butanol from binary mixtures by absorption using water as the absorbent. The dependences of the overall volumetric gas-phase mass transfer coefficient (K(G)a) on the inlet methanol concentration, the inlet 1-butanol concentration, the rotational speed, the gas flow rate, and the liquid flow rate, were explored. The results demonstrated that the inlet methanol and 1-butanol concentrations had a negligible effect on the K(G)a values of methanol and 1-butanol. The K(G)a values of methanol and 1-butanol increased with the rotational speed, the gas flow rate, and the liquid flow rate. The dependence of K(G)a on the gas flow rate was higher than that on the liquid flow rate, revealing that the mass transfer in binary VOCs absorption may be controlled considerably by the mass transfer in gas phase.

Liquid antisolvent preparation of amorphous cefuroxime axetil nanoparticles in a tube-in-tube microchannel reactor

This article presents the preparation of nanoparticles of amorphous cefuroxime axetil (CFA) in a microporous tube-in-tube microchannel reactor (MTMCR). The experimental results indicated that CFA particle with a tunable size of 400-1400 nm could be achieved under a high throughput in the range of 1.5-6L/min. The average particle size decreased with increasing overall volumetric flow rate and decreasing CFA concentration, micropore size, and annular channel width. The produced CFA nanoparticles were characterized by SEM, XRD, FT-IR, DSC and a dissolution test, which indicated that the nanosized CFA was amorphous and exhibited higher dissolution rate compared to the raw CFA. The MTMCR might offer a general and facile pathway for mass production of the nanoparticles of hydrophobic pharmaceuticals thanks to its high throughput capacity and excellent micromixing performance.

Evaluation of alkanolamine solutions for carbon dioxide removal in cross-flow rotating packed beds

The removal of CO(2) from a 10 vol% CO(2) gas by chemical absorption with 30 wt% alkanolamine solutions containing monoethanolamine (MEA), piperazine (PZ), and 2-amino-2-methyl-1-propanol (AMP) in the cross-flow rotating packed bed (RPB) was investigated. The CO(2) removal efficiency increased with rotor speed, liquid flow rate and inlet liquid temperature. However, the CO(2) removal efficiency decreased with gas flow rate. Also, the CO(2) removal efficiency was independent of inlet gas temperature. The 30 wt% alkanolamine solutions containing PZ with MEA were the appropriate absorbents compared with the single alkanolamine (MEA, AMP) and the mixed alkanolamine solutions containing AMP with MEA. A higher portion of PZ in alkanolamine solutions was more favorable to CO(2) removal. Owing to less contact time in the cross-flow RPB, alkanolamines having high reaction rates with CO(2) are suggested to be used. For the mixed alkanolamine solution containing 12 wt% PZ and 18 wt% MEA, the highest gas flow rate allowed to achieve the CO(2) removal efficiency more than 90% at a liquid flow rate of 0.54 L/min was of 29 L/min. The corresponding height of a transfer unit (HTU) was found to be less than 5.0 cm, lower than that in the conventional packed bed.

Applications of micromixing technology

This review presents an application of micromixer technologies, which have driven a number of critical research trends over the past few decades, particularly for chemical and biological fields. Micromixer technologies in this review are categorized according to their applications: (1) chemical applications, including chemical synthesis, polymerization, and extraction; (2) biological applications, including DNA analysis, biological screening enzyme assays, protein folding; and (3) detection/analysis of chemical or biochemical content combined with NMR, FTIR, or Raman spectroscopies. In the chemical application, crystallization, extraction, polymerization, and organic synthesis have been reported, not only for laboratory studies, but also for industrial applications. Microscale techniques are used in chemical synthesis to develop microreactors. In clinical medicine and biological studies, microfluidic systems have been widely applied to the identification of biochemical products, diagnosis, drug discovery, and investigation of disease symptoms. The biological and biochemical applications also include enzyme assays, biological screening assays, cell lysis, protein folding, and biological analytical assays. Nondestructive analytical/detection methods have yielded a number of benefits to chemical and biochemical processes. In this chapter, we introduce analytical methods those are frequently integrated into micromixing technologies, such as NMR, FT-IR, and Raman spectroscopies. From the study of micromixers, we discovered that the Re number and mixing time depends on the specific application, and we clustered micromixers in various applications according to the Re number and mixing performance (mixing time). We expect that this clustering will be helpful in designing of micromixers for specific applications.