ABSTRACT
The far infrared (1 similar to 10 THz) and mid-infrared (400 similar to 4 000 cm(-1)) spectra of six common antibiotics (Ofloxacin capsules, Ofloxacin tablets, Norfloxacin capsules, Azithromycin tablets, Roxithromycin tablets and Levofloxacin hydrochloride tablets), three antiviral drugs for COVID-19 (Ribavirin tablets, Abidol hydrochloride tablets and Chloroquine phosphate tablets) and an expectorant drug (Ambroxol hydrochloride tablets) within shelf-life were studied. The effects of vehicles and another high temperature environment (65 degrees C) on the structure and crystal form of drugs were simulated and fed back to the changes in infrared spectra. After two months of continuous experiments, it was found that the structure and crystal form of other drugs had hardly changed except in ambroxol hydrochloride tablets. When capsule drugs were placed in high-temperature environment for a long time, the epidermis would become brittle and easy to rupture, but the efficacy of internal drugs had hardly changed. Taking fluoroquinolone antibiotics (Ofloxacin and Norfloxacin) as examples, combined with density functional theory (DFT) and the potential energy distribution (PED) method, the theoretical infrared spectra of the two antibiotics monomers, polymers and crystals were calculated by Crystal 14 and Gaussian 16 software with B3LYP/6-311++G(d,p) basis set. The vibrational modes and their contribution rates corresponding to all characteristic peaks were obtained, and the experimental spectrum was accurately identified. It was also found that from monomer to polymer and then to crystal, the stacking force (pi-pi interaction) between lattices accounted for the largest proportion of inter-molecular interaction, more than 90%. Therefore, the theoretical calculation was more consistent with the experimental results only when the crystal with periodic boundary conditions was taken as the initial configuration. The vibrational modes in the far infrared band mainly came from the collective vibration of molecules (vibration accounts for more than 99%, rotation and translation account for less than 1%), and the out-of-plane bending caused by inter-molecular hydrogen bond and Van der Waals force contributes the most, more than 90%. In the mid-infrared band, there were also a certain proportion of inter-molecular interactions. For example, the peaks of norfloxacin at 1 440 cm(-1) and ofloxacin at 1 524 cm(-1) can only be reproduced in the theoretical spectrum with the crystal as the configuration, respectively, from the collective vibration and the stretching of O-H center dot center dot center dot O bonds.
ABSTRACT
The far infrared (1~10 THz) and mid-infrared (400~4 000 cm-1) spectra of six common antibiotics (Ofloxacin capsules, Ofloxacin tablets, Norfloxacin capsules, Azithromycin tablets, Roxithromycin tablets and Levofloxacin hydrochloride tablets), three antiviral drugs for COVID-19 (Ribavirin tablets, Abidol hydrochloride tablets and Chloroquine phosphate tablets) and an expectorant drug (Ambroxol hydrochloride tablets) within shelf-life were studied. The effects of vehicles and another high temperature environment (65 ℃) on the structure and crystal form of drugs were simulated and fed back to the changes in infrared spectra. After two months of continuous experiments, it was found that the structure and crystal form of other drugs had hardly changed except in ambroxol hydrochloride tablets. When capsule drugs were placed in high-temperature environment for a long time, the epidermis would become brittle and easy to rupture, but the efficacy of internal drugs had hardly changed. Taking fluoroquinolone antibiotics (Ofloxacin and Norfloxacin) as examples, combined with density functional theory (DFT) and the potential energy distribution (PED) method, the theoretical infrared spectra of the two antibiotics monomers, polymers and crystals were calculated by Crystal 14 and Gaussian 16 software with B3LYP/6-311++G(d,p) basis set. The vibrational modes and their contribution rates corresponding to all characteristic peaks were obtained, and the experimental spectrum was accurately identified. It was also found that from monomer to polymer and then to crystal, the stacking force (π-π interaction) between lattices accounted for the largest proportion of inter-molecular interaction, more than 90%. Therefore, the theoretical calculation was more consistent with the experimental results only when the crystal with periodic boundary conditions was taken as the initial configuration. The vibrational modes in the far infrared band mainly came from the collective vibration of molecules (vibration accounts for more than 99%, rotation and translation account for less than 1%), and the out-of-plane bending caused by inter-molecular hydrogen bond and Van der Waals force contributes the most, more than 90%. In the mid-infrared band, there were also a certain proportion of inter-molecular interactions. For example, the peaks of norfloxacin at 1 440 cm-1 and ofloxacin at 1 524 cm-1 can only be reproduced in the theoretical spectrum with the crystal as the configuration, respectively, from the collective vibration and the stretching of O-H…O bonds. © 2022 Science Press. All rights reserved.
ABSTRACT
Since the outbreak of novel coronavirus pneumonia (COVID-19), many research institutes and enterprises at home and abroad have been accelerating the research of COVID-19 (SARS-CoV-2) antibody drugs. However, the research on effective drugs was limited by the drug polymorphisms. The environment of drug production, storage and use also affected the stability of the drug. As a fast, non-destructive testing method, infrared spectroscopy can reflect the differences in drug structure, crystal form and even manufacturing technique to the vibration spectrum, which greatly improves the efficiency of R&D (research and development). In this paper, three clinical trials were considered effective drugs for the treatment of COVID-19: Chloroquine diphosphate, Ribavirin and Abidol hydrochloride. Their far-infrared spectrum (1~10 THz) and mid-infrared spectrum (400~4 000 cm-1) were measured by Fourier transform infrared spectrometer (FTIR). In the far-infrared spectrum, the characteristic peaks of Ribavirin were around 2.01, 2.68, 3.37, 4.05, 4.83, 5.45, 5.92, 6.42 and 7.14 THz;the characteristic peaks of Chloroquine phosphate were near 1.26, 1.87, 2.37, 3.06, 3.78, 5.09 and 6.06 THz;the characteristic peaks of Abidol hydrochloride were located near 2.24, 3.14, 3.72, 4.25 and 5.38 THz. Based on density functional theory, the B3LYP hybrid functional and 6-311++G (d, p) basis sets were selected to analyze the vibrational modes corresponding to all characteristic peaks in the spectrum using Crystal14 and Gaussian 16 software, and the accurate identification of the vibration spectrum was realized. The vibrational modes originated from the molecules' collective vibration in the far infrared region. In the mid-infrared band, below 2 800 cm-1, the vibrational modes mainly came from the in-plane and out-of-plane bending and rocking of the group;Above 2 800 cm-1, the vibrational modes transited to the in-plane stretching of C-H, O-H and N-H bonds. Taking the crystal structure with periodic boundary conditions as the initial configuration of the theoretical calculation would make the calculated spectrum more consistent with the experimental one, especially in the far-infrared band and the low-frequency band of mid-infrared (400~1 000 cm-1). This study was of great significance to deeply understand the pharmaceutical characteristics, drug interactions, control of drug production process, and guide the storage and use of antiviral drugs such as Chloroquine phosphate, Ribavirin and Abidol hydrochloride. © 2022 Science Press. All rights reserved.