Validated Stability-Indicating HPTLC Method for Cefixime and Azithromycin with Preparative Isolation, Identification, and Characterization of Degradation Products

Stability-indicating High-Performance Thin-Layer Chromatography (HPTLC) method for simultaneous estimation of cefixime trihydrate and azithromycin dihydrate was developed. Both the drugs were subjected to different stress conditions recommended by International Conference on Harmonization (ICH) guideline Q1A (R2). Forced degradation was carried out for hydrolytic, oxidative, photolytic, and thermal degradation conditions. Cefixime was susceptible for degradation under all stress conditions showing four degradation products (CI-IV). However, azithromycin formed only one degradation product (AI) under acid hydrolysis. Aluminum plates precoated with silica gel 60F(254) were used as the stationary phase while mixture of ethyl acetate-methanol-acetone-toluene-ammonia (1:5:7:0.5:0.5, v/v) was used as mobile phase. Detection wavelength used was 235 nm for CEFI and CI-IV. AZI and AI were detected by post development derivatization, spraying with sulfuric acid-ethanol (1:4, v/v) followed by heating at 100 degrees C for 5 min. Degradation products were isolated by preparative HPTLC and characterized by MS/MS. The developed method was validated for linearity, precision, accuracy, specificity, and robustness and has been successfully applied in the analysis of these drugs in tablet dosage form.