Stability-Indicating Densitometric HPTLC Analysis of Brimonidine Tartrate in the Bulk Drug and in Eye Drops

Asimple, selective, precise, and stability-indicating HPTLC method for analysis of brimonidine tartrate as the bulk drug and in formulations has been established and validated. Chromatography on aluminum foil silica gel 60F254 plates with methanol-toluene-triethylamine 1:3.5:0.2 (v/v) as mobile phase gave a compact band at RF 0.48 ± 0.02. Densitometric analysis was performed in absorbance mode at 247 nm. Linear regression analysis of peak-area calibration data revealed a good linear relationship with r2 = 0.9965 ± 0.0013 in the concentration range 100–600 ng per band. The mean value ± SD of slope and intercept were 9.047 ± 0.11 and 553.0 ± 39.06. The method was validated for precision, recovery, and robustness. The limits of detection and quantitation were 9.40 and 28.51 ng per band, respectively. Brimonidine tartrate was subjected to hydrolysis (in acid, alkali, and neutral solutions), oxidation, and photodegradation, and was degraded under all these conditions. Statistical analysis proved the method enables selective, precise, and accurate identification and quantitative analysis of brimonidine tartrate as the bulk drug and in dosage forms.