Carbamazepine polymorphism: a re-visitation using Raman imaging

Modeling of the Aqueous Solubility of N-butyl-N-methyl-1-phenylpyrrolo[1,2-a] pyrazine-3-carboxamide: From Micronization to Creation of Amorphous-Crystalline Composites with a Polymer

N-butyl-N-methyl-1-phenylpyrrole[1,2-a] pyrazine-3-carboxamide (GML-3) is a potential candidate for combination drug therapy due to its anxiolytic and antidepressant activity. The anxiolytic activity of GML-3 is comparable to diazepam. The antidepressant activity of GML-3 is comparable to amitriptyline. GML-3 is an 18 kDa mitochondrial translocator protein (TSPO) ligand and is devoid of most of the side effects of diazepam, which makes the research on the creation of drugs based on it promising. However, its low water solubility and tendency to agglomerate prevented its release. This research aimed to study the effect of dry grinding, the rapid expansion of a supercritical solution (RESS), and the eutectic mixture (composite) of GML-3 with polyvinylpyrrolidone (PVP) on the particle size, dissolution rate, and lattice retention of GML-3. The use of supercritical CO2 in the RESS method was promising in terms of particle size reduction, resulting in a reduction in the particle size of GML-3 to 20-40 nm with a 430-fold increase in dissolution rate. However, in addition to particle size reduction after RESS, GML-3 began to show signs of a polymorphism phenomenon, which was also studied in this article. It was found that coarse grinding reduced particle size by a factor of 2 but did not significantly affect solubility or crystal structure. Co-milling with the polymer made it possible to level the effect of the appearance of a residual electrostatic charge on the particles, as in the case of grinding, and the increased solubility in the resulting mechanical mixtures of GML-3 with the polymer may also indicate the dissolving properties of polymers (an increase in 400-800 times). The best result in terms of GML-3 solubility was demonstrated by the resulting GML-3:PVP composite at a ratio of 1:4, which made it possible to achieve a solubility of about 80% active pharmaceutical ingredient (API) within an hour with an increase in the dissolution rate by 1600 times. Thus, the creation of composites is the most effective method for improving the solubility of GML-3, superior to micronization.

Exploring the Solid-State Landscape of Carbamazepine during Dehydration: A Low Frequency Raman Spectroscopy Perspective

The solid-state landscape of carbamazepine during its dehydration was explored using Raman spectroscopy in the low- (-300 to -15, 15 to 300) and mid- (300 to 1800 cm^-1) frequency spectral regions. Carbamazepine dihydrate and forms I, III, and IV were also characterized using density functional theory with periodic boundary conditions and showed good agreement with experimental Raman spectra with mean average deviations less than 10 cm^-1. The dehydration of carbamazepine dihydrate was examined under different temperatures (40, 45, 50, 55, and 60 °C). Principal component analysis and multivariate curve resolution were used to explore the transformation pathways of different solid-state forms during the dehydration of carbamazepine dihydrate. The low-frequency Raman domain was able to detect the rapid growth and subsequent decline of carbamazepine form IV, which was not as effectively observed by mid-frequency Raman spectroscopy. These results showcased the potential benefits of low-frequency Raman spectroscopy for pharmaceutical process monitoring and control.

Research progress on the application of spectral imaging technology in pharmaceutical tablet analysis

Tablet as a traditional dosage form in pharmacy has the advantages of accurate dosage, ideal dissolution and bioavailability, convenient to carry and transport. The most concerned tablet quality attributes include active pharmaceutical ingredient (API) contents and polymorphic forms, components distribution, hardness, density, coating state, dissolution behavior, etc., which greatly affect the bioavailability and consistency of tablet final products. In the pharmaceutical industry, there are usually industry standard methods to analyze the tablet quality attributes. However, these methods are generally time-consuming and laborious, and lack a comprehensive understanding of the properties of tablets, such as spatial information. In recent years, spectral imaging technology makes up for the shortcomings of traditional tablet analysis methods because it provides non-contact and rich information in time and space. As a promising technology to replace the traditional tablet analysis methods, it has attracted more and more attention. The present paper briefly describes a series of spectral imaging techniques and their applications in tablet analysis. Finally, the possible application prospect of this technology and the deficiencies that need to be improved were also prospected.