LC Determination and Stability Assessment of Macrolide Antibiotics Azithromycin and Spiramycin in Bulk and Tablet Samples

Development and validation of rapid HPLC method for quantifying macrolide antibiotics azithromycin (AZI) and spiramycin (SPI) in bulk and tablet samples is described. Determination was performed on a reversed phase C₁₈ ODB column (250×4.6 nm I.D) at ambient temperature, and employing a UV-detection set at 210 nm. The mobile phase consists of acetonitrile –2-methyl-2-propanol–hydrogenphosphate buffer, pH 6.2, with 1.8% triethylamine (32:8: up to 100, v/v/v), delivered at a flow-rate of 1.1 mL min^-1. The assay is linear in concentration ranges of: 0.004–4.8 and 0.0003–1.2 mg mL⁻¹ for azithromycin and spiramycin, respectively, with detection limit of 0.02% for SPI and 0.03% for AZI. Recovery experiments revealed recovery of 98.51–100.82%. The applicability of this method in stability assessment studies is evaluated.