Comparison of Differential Scanning Calorimetry, Powder X-ray Diffraction, and Solid-state Nuclear Magnetic Resonance Spectroscopy for Measuring Crystallinity in Amorphous Solid Dispersions - Application to Drug-in-Polymer Solubility

Three-Dimensional Atomic-Level Structure of an Amorphous Glucagon-Like Peptide-1 Receptor Agonist

Amorphous formulations are increasingly used in the pharmaceutical industry due to their increased solubility, but their structural characterization at atomic-level resolution remains extremely challenging. Here, we characterize the complete atomic-level structure of an amorphous glucagon-like peptide-1 receptor (GLP-1R) agonist using chemical shift driven NMR crystallography. The structure is determined from measured chemical shift distributions for 17 of the 32 carbon atoms and 16 of the 31 hydrogen atoms in the molecule. The chemical shifts are able to provide a detailed picture of the atomic-level conformations and interactions, and we identify the structural motifs that play a major role in stabilization of the amorphous form. In particular, hydrogen bonding of the carboxylic acid proton is strongly promoted, although no carboxylic acid dimer is formed. Two orientations of the benzodioxole ring are promoted in the NMR structure, corresponding to a significant stabilization mechanism. Our observation that inclusion of water leads to stabilization of the carboxylic acid group might be used as a strategy in future formulations where hydrogen bonding between neighboring molecules may otherwise be hindered by sterics.

Multi-scale phase separation in poly(D,L-lactide-co-glycolide) and palmitic acid blends using neutron and X-ray scattering

In this work neutron and X-ray scattering are used to quantitatively characterize multi-scale phase separation in a model blend of poly(D,L-lactide-co-glycolide) or poly(D,L-lactide), both synthetic biodegradable polymers, and palmitic acid. We find that phase separation occurs on two different length scales from tens of nanometers to microns. Moreover, the large-scale phase separation mechanism is sensitive to the lactide to glycolide ratio of the polymer matrix and can limit the growth of nanoscale domains of the dispersed palmitic acid. The multiscale structure in these composite materials is directly tied to function in pharmaceutical applications where phase separation and small molecule crystallization are factors that determine controlled release behaviors and drug efficacy.

Patient in-use, room temperature and accelerated conditions stability evaluation of FDA approved clopidogrel hydrogen sulfate products

The objective of the study was to evaluate patient in-use, room temperature, and accelerated conditions stability of FDA-approved products of clopidogrel hydrogen sulfate (CHS). Four products (A, B, C and D) were stored at 25 °C/60% RH (room temperature), 30 °C/75% RH (patient in-use) and 40 °C/75% RH (accelerated) stability conditions for 12 weeks. The products were characterized for physicochemical properties such as hardness, disintegration, assay, impurities, dissolution, Fourier-transformed infrared (FTIR), near-infrared (NIR), hyperspectral imaging, and X-ray powder diffraction (XRPD). Absorption spectroscopic and diffractometry data indicated polymorphic forms present in the products were not identical. Products A and D contained form Ⅱ, while Products B and C contained form Ⅰ of the drug. No form Ⅰ to form Ⅱ and vice-versa transformation was observed in products after exposure to stability conditions. However, an increase in crystallinity was observed with storage conditions especially at 40 °C/75% RH. Impurity C and dissolution met pharmacopeial specifications. Dissolved drug varied from 95.2 to 97.1% in 30 min and impurity C content was 0.04-0.57%. After storage at various conditions, impurity C content increased insignificantly, still met pharmacopeial specification. However, Products stored at 30 °C/75% RH (patient in-use) and 40 °C/75% RH failed to meet dissolution specification of 85% in 30 min due to an increase in crystallinity. In conclusion, FDA approved products of CHS contained different polymorphic forms, and crystallinity may increase on exposure to patient in-use condition which may impact clinical outcomes.

Controlled release of dasatinib from cyclodextrin-based inclusion complexes by mechanochemistry: A computational and experimental study

Dasatinib, a potent tyrosine kinase inhibitor, is widely used to treat chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia. However, its poor aqueous solubility and high first-pass metabolism result in limited oral bioavailability and potentially severe side effects, such as cardiotoxicity, hepatotoxicity, and pulmonary complications, which are intensified by rapid concentration peaks in the bloodstream. To address these challenges, this study examines the development of a controlled-release formulation of dasatinib using cyclodextrins as macrocyclic receptors to form inclusion complexes. Cyclodextrins, known for their ability to form host-guest complexes, enhance drug solubility and stability while enabling controlled drug release and aligning with green chemistry principles when synthesized mechanochemically. Different solid-state and solution-based characterization methods confirmed successful complexation and drug amorphization. Additionally, molecular dynamics simulations provided valuable insights into the binding interactions between dasatinib and cyclodextrins in both gas-phase and aqueous medium, simulating experimental conditions in the absence of a solvent and a physiological environment. Formulated tablets exhibited enhanced solubility and improved in vitro release profiles, suggesting a potential reduction in adverse side effects and improved patient compliance. The results demonstrate the efficacy of cyclodextrins as carriers for dasatinib, highlighting their potential to improve the drug's therapeutic profile in leukemia treatment by facilitating a steady, controlled release and minimizing toxicity.

Crystal structure validation of verinurad via proton-detected ultra-fast MAS NMR and machine learning

The recent development of ultra-fast magic-angle spinning (MAS) (>100 kHz) provides new opportunities for structural characterization in solids. Here, we use NMR crystallography to validate the structure of verinurad, a microcrystalline active pharmaceutical ingredient. To do this, we take advantage of 1H resolution improvement at ultra-fast MAS and use solely 1H-detected experiments and machine learning methods to assign all the experimental proton and carbon chemical shifts. This framework provides a new tool for elucidating chemical information from crystalline samples with limited sample volume and yields remarkably faster acquisition times compared to 13C-detected experiments, without the need to employ dynamic nuclear polarization.

Simultaneous XRD-DSC identifies correct drug-polymer solubility and miscibility for enantiotropic solid forms

Thermodynamic properties, including solubility and miscibility, which are highly correlated with amorphous solid dispersion physical stability were identified for the complex solid forms of bromopropamide using simultaneous X-ray diffraction (XRD)-differential scanning calorimetry (DSC). The most stable solid form of bromopropamide was crystallized and its crystal structure was solved. The crystallized material was characterized using simultaneous XRD-DSC measurements, which allowed dual analyses of a single sample. Transitions of bromopropamide during heating resulted in observation of the unique diffraction patterns of its different solid forms. The dissolution endpoint (Tend) was measured for various mixtures of bromopropamide and polyvinylpyrrolidone-vinyl acetate random copolymer (PVPVA). The use of XRD-DSC allowed confident and accurate measurements of the Tend for a large range of compositions, assisting in the estimation of drug-polymer solubility and miscibility. Thermodynamic properties identified using combined XRD-DSC were further compared to those obtained using only DSC data. It was found that DSC data in isolation can lead to ambiguity, misinterpretations, and incorrect conclusions, especially for a solid demonstrating multiple, closely related forms.

Navigating the Solution to Drug Formulation Problems at Research and Development Stages by Amorphous Solid Dispersion Technology

Amorphous Solid Dispersions (ASDs) have indeed revolutionized the pharmaceutical industry, particularly in drug solubility enhancement. The amorphous state of a drug, which is a highenergy metastable state, can lead to an increase in the apparent solubility of the drug. This is due to the absence of a long-range molecular order, which results in higher molecular mobility and free volume, and consequently, higher solubility. The success of ASD preparation depends on the selection of appropriate excipients, particularly polymers that play a crucial role in drug solubility and physical stability. However, ASDs face challenges due to their thermodynamic instability or tendency to recrystallize. Measuring the crystallinity of the active pharmaceutical ingredient (API) and drug solubility is a complex process that requires a thorough understanding of drug-polymer miscibility and molecular interactions. Therefore, it is important to monitor drug solids closely during preparation, storage, and application. Techniques such as solid-state nuclear magnetic resonance (ssNMR), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, and dielectric spectroscopy have been successful in understanding the mechanism of drug crystallization. In addition, the continuous downstream processing of drug-loaded ASDs has introduced new automated methods for consistent ASD production. Advanced techniques such as hot melt extrusion, KinetiSol, electro spraying, and electrospinning have gained popularity. This review provides a comprehensive overview of Amorphous Solid Dispersions (ASDs) for oral drug delivery. It highlights the critical challenges faced during formulation, the impact of manufacturing variables, theoretical aspects of drug-polymer interaction, and factors related to drug-polymer miscibility. ASDs have been recognized as a promising strategy to improve the oral bioavailability of poorly water-soluble drugs. However, the successful development of an ASD-based drug product is not straightforward due to the complexity of the ASD systems. The formulation and process parameters can significantly influence the performance of the final product. Understanding the interactions between the drug and polymer in ASDs is crucial for predicting their stability and performance.

Polymorphic transitions in flufenamic acid-trehalose composites

The combination of poorly-soluble drugs with small molecule co-formers to generate amorphous solid dispersions (ASDs) has great potential to improve dissolution rate and kinetic solubility, and thus increase the bioavailability of these active ingredients. However, such ASDs are known to be unstable and to crystallise upon storage or heating. In this work, we explore the crystallisation of flufenamic acid (FFA) from ASDs prepared with trehalose. FFA-trehalose mixtures were prepared at a range of w/w composition ratios, heated to melting and crash cooled to form ASDs. They were then subject to a further heat/cool cycle, which was monitored by simultaneous differential scanning calorimetry - X-ray diffraction to observe the phase changes occurring. These varied with the composition of the blend. Upon short-term storage, formulations with low trehalose contents (FFA:trehalose 5:1 w/w) recrystallised into form I FFA, while higher trehalose contents crystallised to FFA form IV. When heated, all FFA trehalose combinations ultimately recrystallised into form I before melting. Upon a second cooling cycle, systems with low trehalose content (FFA:trehalose 5:1 w/w) recrystallised into form IV, while higher trehalose contents led to FFA form I. It is thus clear that even with a single excipient it is possible to control the crystallisation pathway through judicious choice of the formulation parameters.

Review of quantitative and qualitative methods for monitoring photopolymerization reactions

Authomatic in-situ monitoring and characterization of photopolymerization.

Development of Inhalable Spray Dried Nitrofurantoin Formulations for the Treatment of Emphysema

A central characteristic of emphysematous progression is the continuous destruction of the lung extracellular matrix (ECM). Current treatments for emphysema have only addressed symptoms rather than preventing or reversing the loss of lung ECM. Nitrofurantoin (NF) is an antibiotic that has the potential to induce lung fibrosis as a side effect upon oral administration. Our study aims to repurpose NF as an inhalable therapeutic strategy to upregulate ECM expression, thereby reversing the disease progression within the emphysematous lung. Spray-dried (SD) formulations of NF were prepared in conjunction with a two-fluid nozzle (2FN) and three-fluid nozzle (3FN) using hydroxypropyl methylcellulose (HPMC) and NF at 1:1 w/w. The formulations were characterized for their physicochemical properties (particle size, morphology, solid-state characteristics, aerodynamic behaviour, and dissolution properties) and characterized in vitro with efficacy studies on human lung fibroblasts. The 2FN formulation displayed a mass mean aerodynamic diameter (MMAD) of 1.8 ± 0.05 µm and fine particle fraction (FPF) of 87.4 ± 2.8% with significantly greater deposition predicted in the lower lung region compared to the 3FN formulation (MMAD: 4.4 ± 0.4 µm; FPF: 40 ± 5.8%). Furthermore, drug dissolution studies showed that NF released from the 2FN formulation after 3 h was significantly higher (55.7%) as compared to the 3FN formulation (42.4%). Importantly, efficacy studies in human lung fibroblasts showed that the 2FN formulation induced significantly enhanced ECM protein expression levels of periostin and Type IV Collagen (203.2% and 84.2% increase, respectively) compared to untreated cells, while 3FN formulations induced only a 172.5% increase in periostin and a 38.1% increase in type IV collagen. In conclusion, our study highlights the influence of nozzle choice in inhalable spray-dried formulations and supports the feasibility of using SD NF prepared using 2FN as a potential inhalable therapeutic agent to upregulate ECM protein production.

Recent Advances in Amorphous Solid Dispersions: Preformulation, Formulation Strategies, Technological Advancements and Characterization

Amorphous solid dispersions (ASDs) are among the most popular and widely studied solubility enhancement techniques. Since their inception in the early 1960s, the formulation development of ASDs has undergone tremendous progress. For instance, the method of preparing ASDs evolved from solvent-based approaches to solvent-free methods such as hot melt extrusion and Kinetisol^®. The formulation approaches have advanced from employing a single polymeric carrier to multiple carriers with plasticizers to improve the stability and performance of ASDs. Major excipient manufacturers recognized the potential of ASDs and began introducing specialty excipients ideal for formulating ASDs. In addition to traditional techniques such as differential scanning calorimeter (DSC) and X-ray crystallography, recent innovations such as nano-tomography, transmission electron microscopy (TEM), atomic force microscopy (AFM), and X-ray microscopy support a better understanding of the microstructure of ASDs. The purpose of this review is to highlight the recent advancements in the field of ASDs with respect to formulation approaches, methods of preparation, and advanced characterization techniques.