ABSTRACT

   This work aimed to develop a simple and rapid spectrophotometric method for the analysis of erythromycin in pharmaceutical dosage forms.  Direct UV and first derivative measurements at the wavelengths of 285 and 300 nm, respectively, in combination with standard addition method gave promising results.  In both techniques, methanol was used as a solvent and dibasic potassium phosphate buffer (pH 8) was used to hydrolyze erythromycin stearate to erythromycin.  Both the direct UV and first derivative measurements using standard addition method illustrated excellent linearity in the concentration range of 3-15 mg/mL (r² > 0.98 and > 0.99, respectively) with good precision (%RSD < 0.65%).  The limits of detection (LOD) of direct UV and first derivative measurements were 0.08 and 1.37 mg/mL, respectively, and the limits of quantitation (LOQ) were 0.24 and 4.17 mg/mL, respectively.  However, the first derivative measurement showed better % mean recovery (97.6% and 106.5% for brand A and B, respectively, %RSD < 3.34%) than the direct UV measurement (66.03% and 43.80% for brand A and B, respectively, %RSD up to 47.39%).  Thus, the first derivative measurement using standard addition method was valuable for analyzing erythromycin in dosage forms, which excipients strongly interfere the UV absorbance of the drug.