Bo Peng,Zaiyong Zhang,Jian-Rong Wang,Meiqi Li,Qi Zhang,Xuefeng Mei
Discrimination of active pharmaceutical ingredients (APIs) existing as neutral molecules or salts is essential and complicated. However, the discrimination of pharmaceutical salts by confocal Raman micro-spectroscopy remains relatively poorly understood. In this paper, four new salts of triamterene (Tri) cocrystallized with nicotinic acid (NA), benzoic acid (BA), p-toluenesulfonic acid (TA), or isonicotinic acid (INA) were prepared and characterized comprehensively by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarized light microscopy (PLM), and dynamic vapor sorption (DVS). Ionized pteridine is identified by marker peaks in the confocal Raman micro-spectra that are characteristic of CN. The single crystal structures of Tri-NA·H2O and Tri-TA further demonstrate that a proton transfers from the carboxylic group of NA or TA to the pyrimidine N1 atom of Tri and their salts formation take place. The intrinsic dissolution rate (IDR) and apparent equilibrium solubility of these four salts are improved compared to the pure Tri component, especially for Tri-BA. This study provides a valuable insight into pharmaceutical salt discrimination by vibrational spectroscopy and presents that the combination of Tri with an acid can be a possible and promising alternative formulation of Tri.
Two pharmaceutical salts of paliperidone, namely, paliperidone benzoate (PLPT·BA) and paliperidone salicylate (PLPT·SA), were successfully synthesized using benzoic acid (BA) and salicylic acid (SA) as starting materials through a solvent evaporation method. Our study rectified the misidentification of PLPT·BA as a co-crystal in previous research by providing single-crystal structure data and further analysis. The salts’ structures were confirmed through ΔpKa calculations, single-crystal x-ray diffraction (SCXRD) analysis, powder x-ray diffraction (PXRD), and infrared (IR) spectroscopy, while their solubility was also evaluated. Moreover, significant enhancements in thermal stability were observed for both PLPT·BA and PLPT·SA, with increases of 39 K and 32 K, respectively, in their decomposition temperatures compared to pure PLPT. Additionally, intramolecular charge-assisted hydrogen bonds (N + –H···O) were found in both salts, which crystallized in the monoclinic system with the \(P\overline{1}\) P-1 (2) space group. Furthermore, solubility and dissolution rate experiments indicated slight improvements in their solubility and dissolution rate compared to PLPT. This pioneering research provides crucial data on the single-crystal structures and thermal properties of PLPT·BA and PLPT·SA, laying a foundation for further investigations into their potential applications in drug formulations and pharmacology and optimizing drug formulations for enhanced clinical efficacy.
危险品化学品经营许可证（带存储）