A Unified and Isocratic RP-HPLC-UV Method for Azithromycin Determination Across Multiple Pharmaceutical Dosage Forms

Analysis of azithromycin (AZT) by reversed-phase high-performance liquid chromatography (RP-HPLC) is often limited by peak tailing caused by silanol interactions and by reliance on dosage-form-specific Pharmacopeia methods. A unified and column-compatible RP-HPLC-UV method has been developed for the determination of AZT in various pharmaceutical dosage forms. Chromatographic separation was performed on a C18 column using a mobile phase of 0.02% triethylamine (TEA) in 10 mM phosphate buffer (pH 7.0 ± 0.05) and acetonitrile (60:40, v/v) under isocratic conditions with UV detection at 210 nm. Validation according to ICH Q2(R2) demonstrated strong linearity ( R ² = 0.9985) over the range of 0.80–1.20 mg/mL, with %residuals within ±2%. Accuracy ranged from 100.41% to 101.00%, and precision (repeatability and intermediate precision) was confirmed by %RSD < 1%. The method exhibited acceptable robustness under the evaluated conditions; however, retention was sensitive to variations in mobile phase pH, highlighting the importance of maintaining strict pH control during routine analysis. Application to commercial products resulted in assay values of 99.42%–103.65% of label claim, meeting USP and BP specifications. This method provides a streamlined and practical analytical approach for routine quality control of AZT across multiple pharmaceutical dosage forms using a unified chromatographic approach.