Determination of Azithromycin Used in the Treatment Protocol of COVID-19 Based on Spectrophotometric Reactions: A Review

Azithromycin (AZM) drug is one of the most popular antibiotics and was extensively prescribed to treat patients during the first wave of COVID-19 pandemic, especially in developing countries where vaccines were not available. However, although its claimed efficacy to save human life, AZM may pose various detrimental side effects. Consequently, a severe quality control systems and means of this drug in its different pharmaceutical and clinical forms is a crucial phase before its commercialization, prescription, and administration. Among the several techniques used for drugs control and estimation, spectrophotometric method has been the most applied one owing to its simplicity, sensitivity, rapidity and cost effectiveness. However, even though its validation according to the International Conference on Harmonization (ICH) guidelines, determination of AZM via direct spectrophotometry is sometimes hindered due to the lack of chromophore in its molecular structure. Hence, diverse spectrophotometric reactions means have been developed to form selective colored products easily detected in the visible range. Within this vein, owing to its amino groups bearing a lone pair of nitrogen, the common spectrophotometric reactions used for the determination of AZM were oxidative coupling, charge transfer complex, metal complex and ion-pairing reactions. Validation parameters of these reactions such as Beer’s law, molar absorptivity, correlation coefficient, Sandell’s index, relative standard deviation and limits of detection and quantification were gathered and discussed in this review. It was also concluded that the adopted reactions met well the ICH guidelines and their linearity, sensitivity, precision and accuracy were found significantly validated in most reviewed papers. Hence, spectrophotometric reactions means are considered to be promising analytical ways to yield a chromogenic product allowing a precise AZM estimation and would be suitable for application at pharmaceutical laboratories to assure safety and quality control. These reactions can be also applied for other AZM samples such biological fluids and environmental samples.