Applications of synchrotron powder X-ray diffractometry in drug substance and drug product characterization

Pharmaceutical Salts: Comprehensive Insights From Fundamental Chemistry to FDA Approvals (2019-2023)

Pharmaceutical salts are a cornerstone in drug development, offering a robust, economical, and industry-friendly option for improving the crucial physicochemical properties of drugs, particularly solubility and dissolution. This review article explores all critical aspects of salt formation, including its importance, the basic chemistry involved, the principles governing counterion selection, the range of counterions used, and the methods for preparing salts along with their advantages and limitations. Additionally, it explores analytical techniques for confirming salt formation and the different approaches various countries adopt in considering new salts as intellectual property. Furthermore, the review sheds light on US FDA-approved salts from 2019 to 2023, providing a unique perspective by analyzing trends in counterion selection observed in FDA-approved salts during this period. Despite the extensive literature on pharmaceutical salts, a comprehensive review addressing all these critical aspects in a single article with a focus on current trends and particularly on US FDA-approved salts from 2019 to 2023 is lacking. This review bridges this gap by thoroughly exploring all mentioned facets of pharmaceutical salts and providing an up-to-date overview.

Understanding excipient-induced crystallization of spray-dried amorphous solid dispersion

This study investigates the compatibility of excipients with the model system SDI-X and their role in the induced crystallization of the amorphous compound-X in tablet formulations. We aimed to establish a straightforward and practical screening approach for evaluating excipient-induced crystallization of SDI in tablet matrices. Three methodologies-binary powder mixture, binary compact, and bilayer tablets-were employed to qualitatively and quantitatively evaluate the recrystallization of SDI-X with various excipients under accelerated storage conditions. The results demonstrated that binary compacts, providing direct physical contact between SDI-X and excipients, are superior in reflecting realistic drug-excipient contact within pharmaceutical tablets, enabling a more accurate assessment of excipient-induced crystallization for SDI-X. In contrast, the broadly used conventional binary blends can significantly underestimate this risk due to insufficient proximity. In addition, the bilayer tablets further confirmed that crystallization initiates at the contact surface between SDI-X and the excipients. The study highlighted that not only hygroscopicity but also the type of excipient and its physical contact with SDI-X significantly influence the recrystallization extent and rate of SDI-X. Interestingly, less hygroscopic diluents such as mannitol and lactose induced much higher levels of crystallization of SDIs, contrary to expectations based on moisture content alone. This suggests that the excipient type and contact surface are more critical in inducing recrystallization than just the level of moisture. The findings emphasize the need for careful excipient selection, study design, and sample preparation to enable appropriate assessments of SDI-excipient compatibility.

X-ray diffraction and its emerging applications in the food industry

X-ray diffraction (XRD) is an analytical technique that has found several applications focusing on the identification of crystal structure, space groups, plane, and orientation, in addition to qualitative and quantitative phase identification, and polymorphism behavior. An XRD diffractogram pattern/Bragg's peak can also provide valuable information that can be used for various food applications. While this review details the fundamental principles of XRD, the types of XRD systems, instrumentation, and the components thereof, the focus is to serve as a structured resource on explored applications of XRD in food, majorly revolving around food quality and safety. While recent studies relevant to the field are highlighted, leads for futuristic prospects are presented. With its unique approach, the XRD analysis can prove to be a rapid, robust, and sensitive nondestructive approach to food quality evaluation. Recent reports indicate its scope for nonconventional applications such as the assessment of 3D printability of foods, ice crystal formation, and screening food adulterants. Studies also highlight its scope to complement or replace conventional food quality testing approaches that involve the usage of chemicals, extensive sample preparation procedures, derivatization steps and demand long testing times.

The baicalein amorphous solid dispersion to enhance the dissolution and bioavailability and effects on growth performance, meat quality, antioxidant capacity and intestinal flora in Taihang chickens

Baicalein (BAI) is a natural flavonoid with antioxidant, antitumor and antibacterial properties. However, the bioavailability of BAI was limited due to low solubility. This study aims to improve the solubility of BAI through the amorphous solid dispersion (ASD) and evaluate changes in its pharmacokinetics and pharmacodynamics in Taihang chickens. Polyethylene caprolactam-polyvinyl acetate-polyethylene glycol grafted copolymer (Soluplus) was chosen as the carrier, and ASD was prepared by rotary evaporation and was characterized by powder X-ray diffractions (PXRD), differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FT-IR). In vitro dissolution assays were used to screen the optimal ratio of drug to carrier, in vivo pharmacokinetic assays were conducted to investigate the promoting effect on the absorption. In addition, the effects of ASD on the growth performance, meat quality, antioxidant capacity and intestinal flora were investigated. ASD (1:9 and 2:8) did not exhibit crystal diffraction peaks of BAI in PXRD or endothermic peaks in DSC, indicating the successful preparation of ASD. The results of in vitro dissolution assay showed that the cumulative dissolution rate of ASD (2:8) within 600 min was 52.67%, which was 7.84-fold higher than BAI. The pharmacokinetic results showed that the peak concentration (Cmax) and the area under the drug-time curve (AUC0∼24) of ASD (2:8) was (5.20 ± 0.82) μg/mL and (17.03 ± 0.67) μg·h/mL, which was 1.91 and 2.64-fold higher than BAI, respectively. Dietary supplementation of BAI and ASD could increase average daily gain (ADG), while decrease feed conversion ratio (FCR), but there was no significant difference (P > 0.05). The drip loss of BAIASD group was lower than BAI group (P < 0.05). In addition, the antioxidant capacity of Taihang chickens were enhanced, the diversity and the abundance of beneficial bacteria was improved. Results of BAI upon the dietary supplementation tested in Taihang chickens, after preparation of ASD, indicating a superior enhancement effect in growth performance, meat quality, antioxidant capacity and intestinal flora due to an improved solubility and optimized bioavailability.

Smartphone-based hand-held polarized light microscope for on-site pharmaceutical crystallinity characterization

Polarized light microscopy (PLM) is a common but critical method for pharmaceutical crystallinity characterization, which has been widely introduced for research purposes or drug testing and is recommended by many pharmacopeias around the world. To date, crystallinity characterization of pharmaceutical solids is restricted to laboratories due to the relatively bulky design of the conventional PLM system, while little attention has been paid to on-site, portable, and low-cost applications. Herein, we developed a smartphone-based polarized microscope with an ultra-miniaturization design ("hand-held" scale) for these purposes. The compact system consists of an optical lens, two polarizers, and a tailor-made platform to hold the smartphone. Analytical performance parameters including resolution, imaging quality of interference color, and imaging reproducibility were measured. In a first approach, we illustrated the suitability of the device for pharmaceutical crystallinity characterization and obtained high-quality birefringence images comparable to a conventional PLM system, and we also showed the great promise of the device for on-site characterization with high flexibility. In a second approach, we employed the device as a proof of concept for a wider application ranging from liquid crystal to environmental pollutants or tissues from plants. As such, this smartphone-based hand-held polarized light microscope shows great potential in helping pharmacists both for research purposes and on-site drug testing, not to mention its broad application prospects in many other fields.

A comparison of deep-learning-based inpainting techniques for experimental X-ray scattering

The implementation is proposed of image inpainting techniques for the reconstruction of gaps in experimental X-ray scattering data. The proposed methods use deep learning neural network architectures, such as convolutional autoencoders, tunable U-Nets, partial convolution neural networks and mixed-scale dense networks, to reconstruct the missing information in experimental scattering images. In particular, the recovered pixel intensities are evaluated against their corresponding ground-truth values using the mean absolute error and the correlation coefficient metrics. The results demonstrate that the proposed methods achieve better performance than traditional inpainting algorithms such as biharmonic functions. Overall, tunable U-Net and mixed-scale dense network architectures achieved the best reconstruction performance among all the tested algorithms, with correlation coefficient scores greater than 0.9980.

Sensing technologies and experimental platforms for the characterization of advanced oral drug delivery systems

Complex and miniaturized oral drug delivery systems are being developed rapidly for targeted, controlled drug release and improved bioavailability. Standard analytical techniques are widely used to characterize i) drug carrier and active pharmaceutical ingredients before loading into a delivery device (to ensure the solid form), and ii) the entire drug delivery system during the development process. However, in light of the complexity and the size of some of these systems, standard techniques as well as novel sensing technologies and experimental platforms need to be used in tandem. These technologies and platforms are discussed in this review, with a special focus on passive delivery systems in size range from a few 100 µm to a few mm. Challenges associated with characterizing these systems and evaluating their effect on oral drug delivery in the preclinical phase are also discussed.