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Macrolide antibiotics are broad-spectrum, with activity against a range of Gram-positive, Gram-negative organisms and some anaerobes. The components of macrolide antibiotics are generally complicated. Therefore, it is very important to establish impurity profiles of these antibiotics to ensure their safety and process control. Compared with classical methods, the liquid chromatography-mass spectrometry method is particularly advantageous to characterize minor components at trace levels in terms of sensitivity, efficiency and selectivity, thus more and more widely used in establishments of impurity profiles. In this study, the general approaches to characterize minor components in complex pharmaceutical matrix, fragmentation pathways of 14- and 16-membered macrolide antibiotics and the establishment of the impurity profile of acetylspiramycin were given to provide valuable enlightenments to establish the impurity profiles of pharmaceutical products.

The paper is to report the establishment of an HPLC method for determination of the components of bitespiramycin and its products, and to evaluate the components profile of bitespiramycin and its related products. Liquid chromatography combined with mass spectrometry (LC-MS) was used to identify the nine major components of the reference substance of bitespiramycins. The nine components of bitespiramycins and its products have been quantified by HPLC with gradients elution methods. The content of the component of 4"-O-isovalerylspiramycin III was not less than 35%, the content of the components of 4"-O-isovalerylspiramycin (I + II + III) was not less than 60%, and the contents of the nine components of bitespiramycin were not less than 80%, separately. In addition to the components mentioned above, there also exists some other impurities, however, with lower contents. This gradient elution HPLC method reported by this paper is considered to be suitable for the quality control of bitespiramycin.

Aim: To propose a novel polarographic method for the determination of acetylspiramycin (ASPM) is proposed., Methods: In 0.1 mol x L(-1) NH4Cl-NH3 x H2O (pH 8.9) buffer containing dissolved oxygen, ASPM yielded a sensitive parallel catalytic hydrogen wave with the peak potential of -1.63 V (vs SCE) by single sweep polarography., Results: The 2nd order derivative peak currents (i(p)") of the parallel catalytic hydrogen waves of ASPM showed a linear relationship with its concentrations in the range from 1.74 x 10(-3) microg x mL(-1) to 3.84 microg x mL(-1) (r = 0.9979, n=13). Its detection limit was 5.80 x l0(-4) microg x mL(-1) (3sigma) and RSD (n=13) was 1.24% at the concentration level of 0.871 microg x mL(-1)., Conclusion: The proposed method could be applied to the determination of ASPM in ASPM tablets.

Aim: To establish a new and simple flow injection method for the rapid determination of acetylspiramycin (ASPM)., Methods: ASPM was determined by chemiluminescence (CL) method combined with flow injection (FI) technology, which was based on the inhibitive effect of ASPM on the chemiluminescence reaction of the luminol-K3Fe (CN)6 system., Results: The decrease of chemiluminescence intensity was proportional to the logarithm of ASPM concentration (0.1-100) microgram.L-1, the detection limit was 40 ng.L-1 (3 sigma). The whole process, including sampling and washing, could be completed in 0.5 min with a RSD less than 3.0% (n = 5)., Conclusion: The FI-CL method is of both high sensitivity and good selectivity giving a throughput of 120 h-1. The proposed method was applied successfully to the determination of ASPM in pharmaceutical preparations and human urine without any pre-treatment. It was found that the ASPM concentration reached its maximum after being orally administrated for two hours.