Several emerging approaches are gaining traction in preclinical research settings: Raman spectroscopy: Surface-enhanced Raman spectroscopy (SERS) enables label-free detection of glutathione in biological samples
Humans with -glutamyl transpeptidase deficiency have been reported, and these individuals display increased glutathione concentration in urine (glutathionuria) and in blood plasma, and some display central nervous system abnormalities
Wang A, Wan X, Zhuang P, Jia W, Ao Y, Liu X, et al
Feb 6 [cited 2022 Apr 8];102(2_Suppl):324
First, the Instamed sublingual strips are formulated for up to 92% bioavailability high enough that the realistic gap between sublingual and injectable delivery is much smaller than the theoretical difference suggests, particularly once you account for degradation in reconstituted injectable vials