L-Homoarginine-13C7,15N4 (hydrochloride) is the 13C- and 15N-labeled H-HomoArg-OH.HCl. H-HomoArg-OH.HCl is an endogenous metabolite.
References
[1] Russak EM, et al. Impact of Deuterium Substitution on the Pharmacokinetics of Pharmaceuticals. Ann Pharmacother. 2019;53(2):211-216. DOI:10.1177/1060028018797110