A Rapid Assessment Model for Liver Toxicity of Macrolides and an Integrative Evaluation for Azithromycin Impurities.

Impurities in pharmaceuticals of potentially hazardous materials may cause drug safety problems. Macrolide antibiotic preparations include active pharmaceutical ingredients (APIs) and different types of impurities with similar structures, and the amount of these impurities is usually very low and difficult to be separated for toxicity evaluation. Our previous study indicated that hepatotoxicity induced by macrolides was correlated with c-fos overexpression. Here, we report an assessment of macrolide-related liver toxicity by ADMET prediction, molecular docking, structure-toxicity relationship, and experimental verification via detection of the c-fos gene expression in liver cells. The results showed that a rapid assessment model for the prediction of hepatotoxicity of macrolide antibiotics could be established by calculation of the -CDOCKER interaction energy score with the FosB/JunD bZIP domain and then confirmed by the detection of the c-fos gene expression in L02 cells. Telithromycin, a positive compound of liver toxicity, was used to verify the correctness of the model through comparative analysis of liver toxicity in zebrafish and cytotoxicity in L02 cells exposed to telithromycin and azithromycin. The prediction interval (48.1∼53.1) for quantitative hepatotoxicity in the model was calculated from the docking scores of seven macrolide antibiotics commonly used in clinics. We performed the prediction interval to virtual screening of azithromycin impurities with high hepatotoxicity and then experimentally confirmed by liver toxicity in zebrafish and c-fos gene expression. Simultaneously, we found the hepatotoxicity of azithromycin impurities may be related to the charge of nitrogen (N) atoms on the side chain group at the C5 position via structure-toxicity relationship of azithromycin impurities with different structures. This study provides a theoretical basis for improvement of the quality of macrolide antibiotics.

Guidelines and strategy of the International Conference of Harmonization (ICH) and its member states to overcome existing impurity control problems for antibiotics in China.

In the present report, we review the technical guidelines and principles on impurity research and control for antibiotics established by various agencies, including the International Conference of Harmonization (ICH), the US Food and Drug Administration (FDA), the European Medicines Agency (EMA) and the China Food and Drug Administration (CFDA). Progresses with the US Pharmacopoeia (USP), the European Pharmacopoeia (EP) and the Chinese Pharmacopoeia (ChP) to control impurities in antibiotics are also presented. Next, our discussion is focused on analyzing the CFDA's requirements on impurity research and control for antibiotics, and the implementation of ICH, FDA and other technical guidelines for generic drugs impurity control in China. Existing problems are further reviewed, in order to improve the overall process for the control of antibiotic purity.

Impurity profiling of micronomicin sulfate injection by liquid chromatography-ion trap mass spectrometry.

The characterization of impurities present in micronomicin sulfate injection by liquid chromatography (LC) coupled with mass spectrometry (MS) is described. A reversed phase (RP)-LC method using a C18 column resistant to an alkaline (pH 11) aqueous mobile phase was developed and coupled to MS with an electrospray ionization (ESI) source in the positive ion mode which provides MS(n) capability. A total of thirty six impurities were detected in commercial samples: five impurities were identified by comparison of their fragmentation patterns with those of available related substances, eleven of them were identified in accordance with relevant literature, while the other twenty impurities were newly identified using the MS/MS spectra of the available related reference substances as interpretative templates combined with knowledge of the nature of functional group fragmentation behaviors. This work was applied to evaluate the quality of micronomicin sulfate injection from different manufacturers.