Determination of 13 Azithromycin Impurities in Pharmaceutical Formulations by HPLC-UV

Azithromycin (AZM) is a broad-spectrum, semi-synthetic antibiotic from the macrolide family, used for decades to treat infections caused by bacteria, such as pharyngitis and tonsillitis. During the pandemic, it was possible repositioning azithromycin against the new coronavirus (SARS-Cov-2) as widely publicized, however, the World Health Organization (WHO) does not recommend this therapy. Drugs may contain impurities, which are inevitably produced during their synthesis route, but may also originate throughout the shelf-life of the drug, as degradation products. In the case of AZM, these impurities can reduce the antibacterial activity and increase the toxicity of the drug. To evaluate these impurities, a HPLC-UV/Vis method was developed based on the United States Pharmacopoeia, using 210 nm as the detection wavelength, a C18 column (250 × 4.6 mm; 5 µm), and a mobile phase gradient composed of anhydrous dibasic sodium phosphate buffer, methanol, and acetonitrile. The column temperature and mobile phase flow parameters were determined after the application of 32 factorial experiment as being 55 ºC and 0.9 mL min-1,respectively. The method presented adequate selectivity, precision, accuracy, linearity and robustness, in accordance with the specifications contained in resolutions of the collegiate board (RDC) 166/17. Finally, it was possible to monitor the quality of six batches from five different registration holders available on the Brazilian market.