Systematical Investigation of Different Drug Nanocrystal Technologies to Produce Fast Dissolving Meloxicam Tablets

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.

Nano-enabled agglomerates and compact: Design aspects of challenges

Nanoscale medicine confers passive and active targeting potential. The development of nanomedicine is however met with processing, handling and administration hurdles. Excessive solid nanoparticle aggregation and caking result in low product yield, poor particle flowability and inefficient drug administration. These are overcome by converting the nanoparticles into a microscale dosage form via agglomeration or compaction techniques. Agglomeration and compaction nonetheless predispose the nanoparticles to risks of losing their nanogeometry, surface composition or chemistry being altered and negating biological performance. This study reviews risk factors faced during agglomeration and compaction that could result in these changes to nanoparticles. The potential risk factors pertain to materials choice in nanoparticle and microscale dosage form development, and their interplay effects with process temperature, physical forces and environmental stresses. To render the physicochemical and biological behaviour of the nanoparticles unaffected by agglomeration or compaction, modes to modulate the interplay effects of material and formulation with processing and environment variables are discussed.

A comprehensive analysis of meloxicam particles produced by nanosecond laser ablation as a wet milling technique

Recently, the number of water insoluble and poorly soluble drug compounds has increased significantly. Therefore, growing interest has been witnessed in different particle size reduction techniques to improve the dissolution rates, transport characteristics and bioavailability of drugs. Laser ablation has proven to be an alternative method to the production of nano- and micrometre-sized drug particles without considerable chemical damage. We present the nanosecond laser ablation of drug pastilles in distilled water, targeting meloxicam, a poorly water soluble nonsteroidal anti-inflammatory drug, at different laser wavelengths (248 nm, 532 nm and 1064 nm). Besides chemical characterization, crystallinity, morphology and particle size studies, the mechanism of the particle generation process was examined. The applicability of ablated particles in drug formulation was investigated by solubility, cytotoxicity and anti-inflammatory effect measurements. We showed that laser ablation is a clean, efficient and chemically non-damaging method to reduce the size of meloxicam particles to the sub-micrometre–few micrometre size range, which is optimal for pulmonary drug delivery. Complemented by the excellent solubility (four to nine times higher) and anti-inflammatory (four to five times better) properties of the particles compared to the initial drug, laser ablation is predicted to have wider applications in the development of drug formulations.

Chondroitin Sulfate-Derived Paclitaxel Nanocrystal via π-π Stacking with Enhanced Stability and Tumor Targetability

Nanocrystals with high drug loading have become a viable strategy for solubilizing drugs with poor aqueous solubility. It remains challenging, however, to synthesize nanocrystals with sufficient stability and targeting potential. Here, we report a novel nanocrystal platform synthesized using paclitaxel (PTX) and Fmoc-8-amino-3,6-dioxaoctanoic acid (Fmoc-AEEA)-conjugated chondroitin sulfate (CS) (CS-Fmoc) via π-π stacking to afford a stable formulation with CD44 targetability (PTX NC@CS-Fmoc). The PTX NC@CS-Fmoc exhibited rodlike shapes with an average hydrodynamic size of 173.6 ± 0.7 nm (PDI = 0.11 ± 0.04) and a drug loading of up to 31.3 ± 0.6%. Next, PTX NC@CS-Fmoc was subjected to lyophilization in the absence of cryoprotectants for long-term storage, and after redispersion, PTX NC@CS-Fmoc displayed an average hydrodynamic size of 205.3 ± 2.9 nm (PDI = 0.15 ± 0.01). In murine Panc02 cells, PTX NC@CS-Fmoc showed higher internalization efficiency than that of PTX nanocrystals without CS modification (PTX NC@F127) (P < 0.05) or that of CS-Fmoc micelles (P < 0.05). Moreover, PTX NC@CS-Fmoc appeared to accumulate in both lysosomes and Golgi apparatus, while CS-Fmoc micelles accumulated specifically in the Golgi apparatus. In the orthotopic Panc02 tumor-bearing mice model, PTX NC@CS-Fmoc showed higher tumor-specific accumulation than CS-Fmoc micelles, which also demonstrated comparable tumor growth inhibition as to Nab-PTX. Overall, the CS-Fmoc-derived nanocrystals represent a neat and viable formulation strategy for targeted chemotherapy with great potential for translational studies.

Binary or ternary mixture of solid dispersion: Meloxicam case

The present work was carried out to assess the value of adding water insoluble polymer to meloxicam amorphous solid formulation (ASD). Meloxicam was mixed with polyvinylpyrrolidone (PVP) (1:1 ratio) as a binary mixture and with PVP and ethyl cellulose (1:1:1 ratio) as a ternary mixture. Solvent evaporation method was used to prepare ASD formulations. The differential scanning calorimetry, powder X-Ray diffraction, Cambridge Structural Database and in-vitro dissolution were performed to assess the formulas. The results showed that the addition of insoluble polymer could prevent the recrystallization process during ASD formation. However, the binary mixture showed higher drug release percentage than the ternary mixture. Therefore, a rational amount of insoluble polymer could be considered to control recrystallization and manipulate drug release from ASD formulations.

Preclinical studies of a high drug-loaded meloxicam nanocrystals injection for analgesia

Meloxicam (MLX) is considered to have significant analgesic properties. However, the analgesic effects of MLX are compromised by its poor water solubility and thus the low drug loading. The purpose of this study was to develop a high drug-loaded MLX injection by formulating it into nanocrystals (NCs) for the treatment of analgesia. The developed MLXNCs exhibited satisfactory particle sizes and remarkably in vitro dissolution behaviors. In addition, the plasma concentrations of MLXNCs were comparable with the MLX solution (formulated with 1.0% polyoxyethylene castor oil 35) in rats. The acetic acid-induced writhing tests, hot plate tests and hind paw incision experiments demonstrated that the MLXNCs had significant analgesic effects. The findings provide insights into the developed high drug-loaded MLXNCs and provide new therapeutic options for acute and chronic pain management.

Using Amphiphilic Polymer Micelles as the Templates of Antisolvent Crystallization to Produce Drug Nanocrystals

Biocompatible and biodegradable amphiphilic polymeric micelles (PLA-CMCS-g-OA) were prepared by surface grafting of oleic acid and polylactic acid onto carboxymethyl chitosan and were used as templates for the crystallization of camptothecin. The camptothecin (CPT) nanocrystals prepared by the novel micelle-templated antisolvent crystallization (mt-ASC) method demonstrated higher crystallinity, narrower particle size distribution, and slower release characteristic than those prepared by conventional antisolvent crystallization (c-ASC) using a high initial concentration and fast addition rate. In particular, the CPT release behavior of mt-ASC products in phosphate buffer solutions presented a pH-responsive characteristic with the increasing release rate of CPT under lower pH conditions. This work confirmed that amphiphilic nanomicelle-templated crystallization was an effective method for preparing drug nanocrystals.

Advancement of nanomedicines in chronic inflammatory disorders

Chronic diseases, as stated by the WHO, are a threat to human health which kill 3 out of every 5 people worldwide. Therapeutics for such illnesses can be developed using traditional medicine. However, it is not an easy path from natural products to Western pharmacological and pharmaceutical methods. For several decades, chronic inflammatory disorders, especially in Westernized countries, have increased incidence and prevalence. Several NSAIDs are used to decrease inflammation and pain; however, there are numerous negative consequences of these anti-inflammatory medications, whereas plant-based natural products have anti-inflammatory therapeutic benefits that have little or no adverse effects. Nanoparticles are a new type of drug delivery device that may be designed to provide excellent target selectivity for certain cells and tissues while also having a high drug loading capacity, resulting in better pharmacokinetics, pharmacodynamics (PKPD), and therapeutic bioavailability. The size and polarity of phytochemical compounds make it hard to pass the blood-brain barrier (BBB), blood-vessel endothelial lining, gastrointestinal tract and mucosa. In addition, the gastrointestinal system is enzymatically destroyed. Therefore, nanoparticles or nanocrystals might also be used for encapsulation or conjugation of these chemicals as a method to improve their organic effectiveness through their gastrointestinal stability, absorption rate and dispersion. The therapy of numerous inflammatory illnesses, including arthritis, gastritis, Nephritis, Hepatitis (Type A, B &C), ulcerative colitis, Alzheimer's disease, atherosclerosis, allergic responses (asthma, eczema) or autoimmune disorders, is characterised by nanoparticles. This review paper provides information on the numerous nanosystem described with their probable mechanism to treat chronic inflammatory diseases.

Nanocrystals based pulmonary inhalation delivery system: advance and challenge

Pulmonary inhalation administration is an ideal approach to locally treat lung disease and to achieve systemic administration for other diseases. However, the complex nature of the structural characteristics of the lungs often results in the difficulty in the development of lung inhalation preparations. Nanocrystals technology provides a potential formulation strategy for the pulmonary delivery of poorly soluble drugs, owing to the decreased particle size of drug, which is a potential approach to overcome the physiological barrier existing in the lungs and significantly increased bioavailability of drugs. The pulmonary inhalation administration has attracted considerable attentions in recent years. This review discusses the barriers for pulmonary drug delivery and the recent advance of the nanocrystals in pulmonary inhalation delivery. The presence of nanocrystals opens up new prospects for the development of novel pulmonary delivery system. The particle size control, physical instability, potential cytotoxicity, and clearance mechanism of inhaled nanocrystals based formulations are the major considerations in formulation development.

Meloxicam Carrier Systems Having Enhanced Release and Aqueous Wettability Prepared Using Micro-suspensions in Different Liquid Media

One of the conventional methods of alleviating the problem of poor drug solubility is the particle size reduction. The efficiency of this approach depends on successful formulation suppressing the drug agglomeration. The aim of this study was to circumvent the dissolution problems of model hydrophobic meloxicam drug (MLX) by using liquid media of different wetting capacity to comminute and formulate a rapidly dissolving carrier system without the use of surfactants. Micro-suspensions of MLX were prepared by ball milling, using water or n-Heptane as a liquid medium. The suspensions were used as granulation liquids to formulate granulate from microcrystalline cellulose and lactose mixture. The release kinetics from prepared granulates were studied using the USP-4 dissolution apparatus. Micro-suspensions prepared via wet milling in non-water liquid media exhibited a massive improvement of release rate compared with source meloxicam and they outperformed their water-milled counterparts. The release rates from those formulations, despite not comprising any surfactant, were comparable to those obtained by different authors using surfactant stabilized nanosuspension formulations. Thus, they can present an interesting formulation alternative for hydrophobic drugs that are dissolution limited.

Can machine learning predict drug nanocrystals?

Nanocrystals have exhibited great advantage for enhancing the dissolution rate of water insoluble drugs due to the reduced size to nanoscale. However, current pharmaceutical approaches for nanocrystals formulation development highly depend on the expert experience and trial-and-error attempts which remain time and resource consuming. In this research, we utilized machine learning techniques to predict the particle size and polydispersity index (PDI) of nanocrystals. Firstly, 910 nanocrystal size data and 341 PDI data by three preparation methods (ball wet milling (BWM) method, high-pressure homogenization (HPH) method and antisolvent precipitation (ASP) method) were collected for the construction of the prediction models. The results demonstrated that light gradient boosting machine (LightGBM) exhibited well performance for the nanocrystals size and PDI prediction with BWM and HPH methods, but relatively poor predictions for ASP method. The possible reasons for the poor prediction refer to low quality of data because of the poor reproducibility and instability of nanocrystals by ASP method, which also confirm that current commercialized products were mainly manufactured by BWM and HPH approaches. Notably, the contribution of the influence factors was ranked by the LightGBM, which demonstrated that milling time, cycle index and concentration of stabilizer are crucial factors for nanocrystals prepared by BWM, HPH and ASP, respectively. Furthermore, the model generalizations and prediction accuracies of LightGBM were confirmed experimentally by the newly prepared nanocrystals. In conclusion, the machine learning techniques can be successfully utilized for the predictions of nanocrystals prepared by BWM and HPH methods. Our research also reveals a new way for nanotechnology manufacture.

Advanced modification of drug nanocrystals by using novel fabrication and downstream approaches for tailor-made drug delivery

Drug nanosuspensions/nanocrystals have been recognized as one useful and successful approach for drug delivery. Drug nanocrystals could be further decorated to possess extended functions (such as controlled release) and designed for special in vivo applications (such as drug tracking), which make best use of the advantages of drug nanocrystals. A lot of novel and advanced size reduction methods have been invented recently for special drug deliveries. In addition, some novel downstream processes have been combined with nanosuspensions, which have highly broadened its application areas (such as targeting) besides traditional routes. A large number of recent research publication regarding as nanocrystals focuses on above mentioned aspects, which have widely attracted attention. This review will focus on the recent development of nanocrystals and give an overview of regarding modification of nanocrystal by some new approaches for tailor-made drug delivery.