Sulfonamides (NESOI)

Lines 2935903000 through 2935904800 cover named or categorically defined sulfonamides used specifically as anti-infective agents (antibacterials), while 2935906000 captures other sulfonamide drugs not used as anti-infectives. Non-pharmaceutical sulfonamides — such as ortho-toluenesulfonamide used in plasticizer or resin applications — fall under 2935901500 or the residual non-drug lines. Correct line selection requires both chemical identity documentation and evidence of the substance's intended pharmaceutical or industrial end-use.

The HTS classification is the same regardless of whether the sulfonamide is intended for human or veterinary pharmaceutical use — the tariff lines do not distinguish by species. However, regulatory treatment diverges: human-use drug substances are subject to FDA Center for Drug Evaluation and Research (CDER) admissibility review, while veterinary APIs fall under FDA Center for Veterinary Medicine (CVM) oversight. Both require the foreign manufacturer to hold FDA registration, but the applicable drug master file type and approval pathway differ. Importers should declare the intended use accurately on entry documentation.