Identification, isolation, and characterization of potential degradation products in a triple combination lamivudine, zidovudine, and nevirapine tablet for oral suspension

An unknown impurity (degradation product) present at a level below 0.1% in the initial sample was increased to 0.25% in 50 ◦C 3M stability samples of lamivudine, zidovudine and nevirapine tablets for oral suspension, as detected by gradient reverse phase HPLC. This degradation product was isolated using reverse phase preparative HPLC. Based on the spectral data, the structure of this degradation product is characterized as 1-[5-hydroxymethyl-4-(5-methyl-2,3-dihydro-[1,2,3]triazole-1-yl)-tetrahydrofuran-2-yl]5-methyl-1H-pyrimidine-2,4-(1H,3H)dione. Structural elucidation of this degradation product was carried out using MS, 1H NMR, 13C NMR, DEPT and IR spectral data. The formation of this impurity and its mechanism are discussed.