N-Hydroxysuccinimide-d4 is derived from Succinic Anhydride-d4 (S688773), which is used in the synthesis of propanoyloxy derivatives used as drug absorption modifiers. In addition it is a reagent for novel non-carboxylate inhibitors of AKR1C3. Also, it is the deuterated form of N-Hydroxysuccinimide (H953585), which is an additive used in the carbodiimide method for improved amidations and peptide couplings.