Citalopram hydrobromide: Degradation product characterization and a validated stability-indicating LC-UV method

Abstract

Five degradation products (I-V) of citalopram hydrobromide (CTL) were formed under different forced degradation conditions. Products I and II were formed under hydrolytic conditions while product III-V were formed under photolytic conditions. Products II and IV were found known impurities as citalopram carboxamide and citalopram N-oxide, respectively. Product I was found to be a new impurity which was characterized as 3-hydroxycitalopram N-oxide. The drug and all five degradation products were optimally resolved on a C 8 column with mobile phase composed of acetonitrile and ammonium acetate buffer (pH* 4.5) flowing at a rate of 0.50 mL min-1. The method was linear, precise RSD < 3 (relative standard deviation) and accurate (recovery being 88-97%) in the concentration range of 5-500 μg mL-1 of citalopram. The limits of detection (LOD) and of quantitation (LOQ) were 1 μg mL-1 and 5 μg mL-1, respectively. The photodiode array (PDA) analysis of the degraded CTL solution containing the CTL and all five degradation products revealed each peak to be pure. Hence, the method was suggested to be stability-indicating. © 2011 Sociedade Brasileira de Química.