Stability-Indicating Chromatographic Methods for Determination of Agomelatine in Drug Substance and Drug Product

Three sensitive and validated chromatographic methods were developed for determination of Agomelatine (AGO) in the presence of its degradation products in drug substance and drug product. The first and second methods were normal thin layer chromatographic (NP-TLC) and reversed phase thin layer chromatographic (RP-TLC) methods. Mobile phase consisting of ethyl acetate-ammonia (33%)-methanol (8.5:0.5:1, v/v/v) was used for NP-TLC while for RP-TLC using 0.1% triethylamine (TEA): acetonitrile (60:40 v/v) at pH=2. The chromatograms were scanned at 230 and 280 nm and determined in the range of 0.1-4 and 0.3-4 μg/spot with mean percentage recovery of 99.89 ± 1.141 and 100.01 ± 1.062 for NP-TLC and RP-TLC respectively. The third method was Micellar Liquid Chromatographic (MLC) method using C18 column and a mobile phase consisting of 0.1 M Sodium Dodecyl Sulphate (SDS), 15% butan-1-ol, 0.2% TEA in water adjusted to pH=3. The UV detection was achieved at 230 nm and determined in the range of 0.5-5 μg/mL with mean percentage recovery of 100.13 ± 0.970. The proposed methods were successfully applied as stability indicating methods under different stressed conditions according to the International Conference of Harmonization (ICH) guidelines. The methods showed good selectivity, repeatability, linearity and sensitivity according to the evaluation of the validation parameters.