Towards an improved understanding of drug excipient interactions to enable rapid optimization of nanosuspension formulations

Sorafenib tosylate-loaded nanosuspension: preparation, optimization, and in vitro cytotoxicity study against human HepG2 carcinoma cells

This study aimed to optimize nanosuspension of sorafenib tosylate (an anticancer hydrophobic drug molecule) using a central composite design. Nanosuspension was prepared using a nanoprecipitation-ultrasonication approach. FTIR and DSC analyses demonstrated that the drug and excipients were physicochemically compatible. X-ray powder diffraction analysis confirmed amorphous form of the payload in the formulation. The optimized formulation (batch NSS6) had a zeta potential of -18.1 mV, a polydispersity of 0.302, and a particle size of 97.11 nm. SEM analysis confirmed formation of rod-shaped particles. After 24 h, about 64.45% and 86.37% of the sorafenib tosylate was released in pH 6.8 and pH 1.2, respectively. The MTT assay was performed on HepG2 cell lines. IC50 value of the optimized batch was 39.4 µg/mL. The study concluded that sorafenib tosylate nanosuspension could be a promising approach in the treatment of hepatocellular cancer.

Nanosuspensions in ophthalmology: Overcoming challenges and enhancing drug delivery for eye diseases

This review article provides a comprehensive overview of the advancements in using nanosuspensions for controlled drug delivery in ophthalmology. It highlights the significance of ophthalmic drug delivery due to the prevalence of eye diseases and delves into various aspects of this field. The article explores molecular mechanisms, drugs used, and physiological factors affecting drug absorption. It also addresses challenges in treating both anterior and posterior eye segments and investigates the role of mucus in obstructing micro- and nanosuspensions. Nanosuspensions are presented as a promising approach to enhance drug solubility and absorption, covering formulation, stability, properties, and functionalization. The review discusses the pros and cons of using nanosuspensions for ocular drug delivery and covers their structure, preparation, characterization, and applications. Several graphical representations illustrate their role in treating various eye conditions. Specific drug categories like anti-inflammatory drugs, antihistamines, glucocorticoids, and more are discussed in detail, with relevant studies. The article also addresses current challenges and future directions, emphasizing the need for improved nanosuspension stability and exploring potential technologies. Nanosuspensions have shown substantial potential in advancing ophthalmic drug delivery by enhancing solubility and absorption. This article is a valuable resource for researchers, clinicians, and pharmaceutical professionals in this field, offering insights into recent developments, challenges, and future prospects in nanosuspension use for ocular drug delivery.

Tailoring the use of excipients in bottom-up production of naproxen crystal suspensions via membrane technology

Long-acting crystal suspensions of active pharmaceutical ingredients (API) mostly comprised of an API, a suspension media (water) and excipients and provide sustained API release over time. Excipients are crucial for controlling particle size and to achieve the stability of the API crystals in suspension. A bottom-up process was designed to produce long-acting crystal suspensions whilst investigating the excipient requirements during the production process and the subsequent storage. PVP K30 emerged as the most effective excipient for generating stable naproxen crystals with the desired size of 1 to 15 μm, using ethanol as solvent and water as anti-solvent. Calculations, performed based on the crystal properties and assuming complete PVP K30 adsorption on the crystal surface, revealed lower PVP K30 requirements during storage compared to initial crystal generation. Consequently, a membrane-based diafiltration process was used to determine and fine-tune PVP K30 concentration in the suspension post-crystallization. A seven-stage diafiltration process removed 98 % of the PVP K30 present in the suspension thereby reducing the PVP-to-naproxen ratio from 1:2 to 1:39 without impacting the stability of naproxen crystals in suspension. This work provides insights into the excipient requirements at various production stages and introduce the membrane-based diafiltration for precise excipient control after crystallization.

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.

Nanocrystal-chitosan particles for intra-articular delivery of disease-modifying osteoarthritis drugs

Osteoarthritis is the most common chronic joint disease and a major health care concern due to the lack of efficient treatments. This is mainly related to the local and degenerative nature of this disease. Kartogenin was recently reported as a disease-modifying osteoarthritis drug that promotes cartilage repair, but its therapeutic effect is impeded by its very low solubility. Therefore, we designed a unique nanocrystal-chitosan particle intra-articular delivery system for osteoarthritis treatment that merges the following formulation techniques: nanosize reduction of a drug by wet milling and spray drying. The intermediate formulation (kartogenin nanocrystals) increased the solubility and dissolution rates of kartogenin. The final drug delivery system consisted of an easily resuspendable and ready-to-use microsphere powder for intra-articular injection. Positively charged chitosan microspheres with a median size of approximately 10 µm acted as a mothership drug delivery system for kartogenin nanocrystals in a simulated intra-articular injection. The microspheres showed suitable stability and a controlled release profile in synovial fluid and were nontoxic in human synoviocytes. The cartilage retention skills of the microspheres were also explored ex vivo using cartilage. This drug delivery system shows promise for advancement to preclinical stages in osteoarthritis therapy and scale-up production.

Utilizing Molecular Simulations to Examine Nanosuspension Stability

Drug nanosuspensions offer a promising approach to improve bioavailability for poorly soluble drug candidates. Such formulations often necessitate the inclusion of an excipient to stabilize the drug nanoparticles. However, the rationale for the choice of the correct excipient for a given drug candidate remains unclear. To gain molecular insight into formulation design, this work first utilizes a molecular dynamics simulation to computationally investigate drug-excipient interactions for a number of combinations that have been previously studied experimentally. We find that hydrophobic interactions drive excipient adsorption to drug nanoparticles and that the fraction of polar surface area serves as a predictor for experimental measurements of nanosuspension stability. To test these ideas prospectively, we applied our model to an uncharacterized drug compound, GDC-0810. Our simulations predicted that a salt form of GDC-0810 would lead to more stable nanosuspensions than the neutral form; therefore, we tested the stability of salt GDC-0810 nanosuspensions and found that the salt form readily formed nanosuspensions even without the excipient. To avoid computationally expensive simulations in the future, we extended our model by showing that simple, two-dimensional properties of single drug molecules can be used to rationalize nanosuspension designs without simulations. In all, our work demonstrates how computational tools can provide molecular insight into drug-excipient interactions and aid in rational formulation design.

A New Approach for Preparing Stable High-Concentration Peptide Nanoparticle Formulations

The subcutaneous administration of therapeutic peptides would provide significant benefits to patients. However, subcutaneous injections are limited in dosing volume, potentially resulting in high peptide concentrations that can incur significant challenges with solubility limitations, high viscosity, and stability liabilities. Herein, we report on the discovery that low-shear resonant acoustic mixing can be used as a general method to prepare stable nanoparticles of a number of peptides of diverse molecular weights and structures in water without the need for extensive amounts of organic solvents or lipid excipients. This approach avoids the stability issues observed with typical high-shear, high-intensity milling methods. The resultant peptide nanosuspensions exhibit low viscosity even at high concentrations of >100 mg/mL while remaining chemically and physically stable. An example nanosuspension of cyclosporine nanoparticles was dosed in rats via a subcutaneous injection and exhibited sustained release behavior. This suggests that peptide nanosuspension formulations can be one approach to overcome the challenges with high-concentration peptide formulations.

Spray-dried nanocrystal-loaded polymer microparticles for long-term release local therapies: an opportunity for poorly soluble drugs

Nano- and micro-technologies can salvage drugs with very low solubility that were doomed to pre-clinical and clinical failure. A unique design approach to develop drug nanocrystals (NCs) loaded in extended release polymeric microparticles (MPs) for local treatments is presented here through the case of a potential osteoarthritis (OA) drug candidate for intra-articular (IA) administration. Optimizing a low-shear wet milling process allowed the production of NCs that can be subsequently freeze-dried (FD) and redispersed in a hydrophobic polymer-organic solvent solution to form spray-dried MPs. Results demonstrated a successful development of a ready-to-upscale formulation containing PLGA MPs with high drug NC encapsulation rates that showed a continuous and controlled drug release profile over four months. The screenings and procedures described allowed for identifying and overcoming common difficulties and challenges raised along the drug reduction to nano-size and spray-drying process. Above all, the technical knowledge acquired is intended for formulation scientists aiming to improve the therapeutic perspectives of poorly soluble drugs.

Precellys® Evolution Homogenizer - a versatile instrument for milling, mixing, and amorphization of drugs in preformulation

The aim of this work was the evaluation and introduction of the Bertin Precellys® Evolution homogenizer with Cryolys® as a valuable and versatile tool for the improvement of workflows in the preformulation phase of drug development. The presented pilot experiments indicate that the instrument can be applied for (1) screening of appropriate vehicles for the generation of micro- and nano suspensions, (2) small-scale manufacturing of suspension formulations for preclinical animal studies, (3) drug amorphization and identification of appropriate excipients for amorphous systems, and (4) preparation of homogenous powder blends. The instrument allows the rapid, parallel, and compound-sparing screening of formulation approaches and small-scale formulation manufacturing, in particular for low solubility compounds. For the characterization of generated formulations, miniaturized methods are introduced such as a screening tool for suspension sedimentation and redispersion and a non-sink dissolution model in biorelevant media in microtiter plates. This work summarizes exploratory, proof-of-concept studies and opens up new opportunities for more extended studies with this instrument in various application areas.

Factors affecting the preparation of nanocrystals: characterization, surface modifications and toxicity aspects

INTRODUCTION

The fabrication of well-defined nanocrystals in size and form is the focus of much investigation. In this work, we have critically reviewed several recent instances from the literature that shows how the production procedure affects the physicochemical properties of the nanocrystals.

AREAS COVERED

Scopus, MedLine, PubMed, Web of Science, and Google Scholar were searched for peer-review articles published in the past few years using different key words. Authors chose relevant publications from their files for this review. This review focuses on the range of techniques available for producing nanocrystals. We draw attention to several recent instances demonstrating the impact of various process and formulation variables that affect the nanocrystals' physicochemical properties. Moreover, various developments in the characterization techniques explored for nanocrystals concerning their size, morphology, etc. have been discussed. Last but not least, recent applications, the effect of surface modifications, and the toxicological traits of nanocrystals have also been reviewed.

EXPERT OPINION

The selection of an appropriate production method for the formation of nanocrystals, together with a deep understanding of the relationship between the drug's physicochemical properties, unique features of the various formulation alternatives, and anticipated in-vivo performance, would significantly reduce the risk of failure during human clinical trials that are inadequate.

Nanosuspensions technology as a master key for nature products drug delivery and In vivo fate

The drug nanosuspensions is a universal formulation approach for improved drug delivery of hydrophobic drugs and one the most promising approaches for increasing the biopharmaceutical performance of poorly water-soluble drug substances, especially for nature products. This review aimed to summarize the nanosuspensions preparation approaches and the main technological difficulties encountered in nanosuspensions development, such as guidelines for stabilizers screening, in vivo fate of the intravenously administrated nanosuspensions, and how to realize the intravenously target delivery was reviewed. Furthermore, challenges of nanosuspensions for the nature products delivery also was discussed and commented. Therefore, it hoped to provide reference and assistance for the nanosuspensions production, stabilizers usage, and predictability of in vivo fate and controllability of targeting delivery of the nature products nanosuspensions.

Elaborating the crystal transformation referenced microhydrodynamic model and fracture mechanism combined molecular modelling of irbesartan nanosuspensions formation in wet media milling

In recent years, polymorphic transformation involved in media milling has become a key factor in inducing the instability of nanosuspensions (NSs). The variation trend of microhydrodynamic parameters, including milling intensity factor (F), can be observed under different milling conditions. Therefore, this study first referenced the microhydrodynamic model to explore how formulations and process parameters affect Irbesartan (IRB) form A crystallinity during wet media milling. As a result, the crystallinity of form A was affected by the intermolecular interactions between drug particles and stabilizers. The crystallinity of form A decreased with decreasing drug loading, increasing stirrer speed and bead loading, which depended on the role of F. Milling could promote the transformation from a 1H to 2H tetrazole ring with stabilizers containing -OH, and form B was changed to form A and finally to an amorphous state. Molecular modelling shows that forms A and B are ductile and fragile materials, respectively, and both present anisotropy. When milling beads hit both polymorphs paralleling to the (010) surface, the bead-bead collisions are more helpful in fracturing IRB particles. The results of this study may provide a foundation for controlling crystal transformation and obtaining ideal crystal forms.

Impact of Excipients and Seeding on the Solid-State Form Transformation of Indomethacin during Liquid Antisolvent Precipitation

Long-acting injectables are a unique drug formulation strategy, providing a slow and sustained release of active pharmaceutical ingredients (APIs). In this study, a novel approach that combines liquid antisolvent precipitation with seeding to obtain a stable form of the API indomethacin while achieving the desired particle size distribution is described. It was proven that when a metastable form of indomethacin was initially nucleated, the rate of its transformation to the stable form was influenced by the presence of excipients and seeds (17.10 ± 0.20 μm), decreasing from 48 to 4 h. The final particle size (D50) of the indomethacin suspension produced without seeding was 7.33 ± 0.38 μm, and with seeding, it was 5.61 ± 0.14 μm. Additionally, it was shown that the particle size distribution of the seeds and the time point of seed addition were critical to obtain the desired solid-state form and that excipients played a crucial role during nucleation and polymorphic transformation. This alternative, energy-efficient bottom-up method for the production of drug suspensions with a reduced risk of contamination from milling equipment and fewer processing steps may prove to be comparable in terms of stability and particle size distribution to current industrially accepted top-down approaches.

Review of nanosuspension formulation and process analysis in wet media milling using microhydrodynamic model and emerging characterization methods

Wet media milling is a popular technology used to prepare nanosuspensions. However, the theories and methods to guide the research on the formulation and process affecting wet media milling remain limited. The research on wet media milling follows a "black box" approach to a certain extent. This review focuses on exploring the formulation and process parameters factors in wet media milling. The formulation factors include the concentration, hydrophilicity/hydrophobicity, and structure of the drug and stabilizer, whereas the milling process parameters include the milling speed, milling time, and material, size, and filling volume of milling beads. Contrary to other reviews, this review attempts to quantify and visualize these factors by combining a microhydrodynamic model with emerging characterization methods to provide a scientific basis for the selection of nanosuspension formulations and process parameters, as opposed to the conventional trial-and-error approach.

Multi-directionally evaluating the formation mechanism of 1,4-dihydropyridine drug nanosuspensions through experimental validation and computer-aided drug design

The poor aqueous solubility of 1,4-dihydropyridine drugs needs to be solved urgently to improve the bioavailability. Nanotechnology can improve drug solubility and dissolution by reducing particle size, but usually a specific polymer or surfactant is required for stabilization. In this study, Poloxamer-407(P-407) was screened as the optimal stabilize through energy simulation, molecular docking and particle size. morphological study, X-ray diffraction, differential scanning calorimetry, Fourier transform infrared spectroscopy, Raman, in vitro dissolution test and molecular simulation of interactions were utilized to explore the formation mechanisms of four 1,4-dihydropyridine drugs/P-407 nanosuspensions. The result shows that the optimized nanosuspensions had the particle size in the nano-size range and maintained the original crystal state. The in vitro dissolution rate of the nanosuspension was 3-4 times higher than the corresponding API and could reduce the restriction of drug dissolution in different pH environments. Raman spectroscopy, FTIR and molecular docking simulations provided strong supporting evidence for the formation mechanism of 1,4-dihydropyridine drugs/P-407 nanosuspensions at the molecular level, which confirmed that the stable intermolecular hydrogen bond adsorption and hydrophobic interaction were formed between the drug and P-407. This research will provide practical concepts and technologies, which are helpful to develop nanosuspensions for the same class of drugs.

Progress in the development of stabilization strategies for nanocrystal preparations

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

Exploring space-energy matching via quantum-molecular mechanics modeling and breakage dynamics-energy dissipation via microhydrodynamic modeling to improve the screening efficiency of nanosuspension prepared by wet media milling

Introduction: The preparation of nanosuspensions by wet media milling is a promising technique that increases the bioavailability of insoluble drugs. The nanosuspension is thermodynamically unstable, where its stability might be influenced by the interaction energy between the stabilizers and the drugs after milling at a specific collision energy. However, it is difficult to screen the stabilizers and the parameters of milling accurately and quickly by using traditional analysis methods. Quantum-molecular mechanics and microhydrodynamic modeling can be applied to improve screening efficiency.Areas covered: Quantum-molecular mechanics model, which includes molecular docking, molecular dynamics simulations, and data on binding energy, provides insights into screening stabilizers based on their molecular behavior at the atomic level. The microhydrodynamic model explores the mechanical processes and energy dissipation in nanomilling, and even combines information on the mechanical modulus and an energy vector diagram for the milling parameters screening of drug crystals.Expert opinion: These modeling methods improve screening efficiency and support screening theories based on thermodynamics and physical dynamics. However, how to reasonably combine different modeling methods with their theoretical characteristics and further multidimensional and cross-scale simulations of nanosuspension formation remain challenges.

Lentinan as a natural stabilizer with bioactivities for preparation of drug-drug nanosuspensions

Lentinan is a natural β-glucan with various bioactivities and is combined with chemotherapy drugs for cancer treatment. Regorafenib is an oral multi-kinase inhibitor approved by FDA for treatment of metastatic colorectal cancer, advanced hepatocellular carcinoma, and metastatic gastrointestinal stromal tumors. Regorafenib has poor water solubility and multiple toxicities. We report drug-drug nanosuspensions of regorafenib and lentinan. Results of dynamic light scattering and scanning electron microscopy showed that the mean particle size of the regorafenib-lentinan nanosuspensions was approximately 200 nm and was uniformly distributed. Transmission electron microscopy findings indicated that lentinan stabilized the nanosuspensions by steric manner. Hydrogen bonds and hydrophobic interactions were found between regorafenib and lentinan by molecular dynamics simulation. The results of cytotoxicity assay and pharmacokinetics study in rats showed that the regorafenib-lentinan nanosuspensions reduced the toxicity and enhanced the in vitro anticancer activity and oral bioavailability of regorafenib. Lentinan as a natural stabilizer has the potential using for drug nanosuspensions. Drug-drug nanosuspensions are a new form of combination therapies that can reduce the number of drugs taken by patients and improve their compliance.

Liquid filled hard shell capsules: Current drug delivery influencing pharmaceutical technology

PURPOSE

Gastric absorption apparently is upfront route for drug delivery as it is convenient, economic and mostly suitable for getting the desired systemic effects. Unfortunately, many traditional and newer generation drugs suffer from poor solubility and thereby have lower bioavailability. With a perspective of bringing a novel delivery system in such condition for old/existing/new drugs, liquid filled hard capsules hold promise as delivery system.

METHODS

An organized state-of-the-art literature review including patents was done to accommodate information on the innovations in technology, processes and applications in the field of liquid filling in hard shell capsules.

RESULTS

The review findings revealed the importance of understanding the impact of liquid filled hard shell capsules would have in use of complex drug molecules specially the ones sensitive to light and moisture. This technology can have diverse functions to be used for both immediate and delayed drug release. Technology point of view the band sealing in such hard-shell capsules helps in providing protection against the tampering of the filled capsule.

CONCLUSION

The review gives an insight to the understanding of progression in the technology forefront related to formulation development of liquid formulations to be filled in hard shell capsules for better therapeutic potentials and convenience to the patients.

Can the cavi-precipitation process be exploited to generate smaller size drug nanocrystal?

OBJECTIVE

Cavi-precipitation has the potential to generate drug nanocrystals very efficiently. Achieving smaller than 100 nm particle size for organic drug substances still remained a challenge. The objective of this study was to demonstrate if cavi-precipitation technology can be used to generate smaller than 100 nm drug nanocrystal particle.

SIGNIFICANCE

This study demonstrates that cavi-precipitation process can be used to generate drug nanocrystals of the model compound resveratrol (RVT) consists of crystallites of 30-50 nm size.

METHOD

RVT was dissolved in different organic solvents to prepare the solvent phase (S-phase). Several stabilizers were tested for the organic phase. A combination of SDS and PVP was used stabilizer system in the aqueous anti-solvent phase (AS-phase). The S-phase was added to the AS-phase inside the Emulsiflex C5 homogenizer. Nanosuspension was characterized by laser diffractometry (LD), photon correlation spectroscopy (PCS) and scanning electron microscopy (SEM). The solid state of the suspended particles was investigated by powder X-ray diffractometry (PXRD) and differential scanning calorimetry (DSC).

RESULTS

It was found that DMSO, alone or in combination with acetone in the S-Phase generated the smallest size RVT nanocrystals. The optimum solvent (S) antisolvent (AS) ratio (S:AS) was found to be 3.6:56.4 (v:v). Span 20 was identified as the best stabilizer for the organic phase at a ratio (w:w) of 1:3 (Span 20:RVT). The particles precipitated from different solvents were predominantly crystalline.

CONCLUSIONS

The best sample had a mean particle size (LD) of 167 nm [d(0.5)] which was composed of smaller crystallites having 30-50 nm size (SEM).