Assay of nitrofurantoin oral suspensions contaminated with 3-(5-nitrofurfurylideneamino)hydantoic acid

Article abstract of DOI:10.1002/jps.2600740128

A reversed-phase high-performance liquid chromatographic (HPLC) analysis of oral suspensions for nitrofurantoin (1) and 3-(5-nitrofurfurylideneamino)hydantoic acid (2), an impurity derived from 1, is presented. The concentration of the impurity ranged from 20 to 300 μg/mL in several lots of commercial oral suspensions. Conversion of 1 to 2 with citrate buffer, an excipient in the oral suspension, was achieved; selective hydantoin ring cleavage was accomplished in preference to the generally observed cleavage at the azomethine linkage. The hydantoic acid 2 was synthesized and identified by NMR, IR, TLC, and elemental analysis.