Stability-indicating UPLC, TLC-densitometric and UV-spectrophotometric methods for alcaftadine determination

Three sensitive and precise stability-indicating methods were developed for the determination of alcaftadine in the presence of its degradation products. Efficient separation was achieved using UPLC-UV-MS method by gradient elution with a mobile phase of 0.1% aqueous formic acid (A) and 0.1% formic acid in acetonitrile (B) over concentration range of 0.10-1.00 µg mL^-1. The accuracy was 100.89% ± 0.74 and 99.73% ± 0.78 for UV and MS detection, respectively. A TLC-densitometric method was adopted to separate of the intact drug from its degradation products. Methanol: chloroform: glacial acetic acid (5:4:0.1, v/v/v) was the developing system, detection wavelength was set to 282 nm. R_f values were 0.35, 0.65 and 0.88 for alcaftadine, its acidic and oxidative degradants, respectively. The linearity range was 2.00-27.00 µg/band with mean accuracy of 100.58% ± 0.86. The proposed TLC-densitometric method was utilized for the study of degradation rates of alcaftadine. Finally, a simple UV-spectrophotometric method where an induced dual wavelength was implemented, the method showed a linearity range of 2.00-27.00 µg mL^-1 with mean recovery of 100.15% ± 0.70. The proposed methods were successful for quantitation of alcaftadine in ophthalmic solution and in plasma samples. The obtained results were in accordance with those obtained by previously reported methods.