Good question. NAD IVs have been around for decades, and have been used to treat addiction. NAD IV therapy might have been the best available technology for that, before the discovery of NAD precursors that could get past the rate-limiting steps that can sometimes prevent NAD biosynthesis from Niacin (NA) and Nicotinamide (NAM).
For several decades, IV NAD+ has been used as a holistic ‘underground’ approach for the treatment of various forms of addiction...NAD+ precursors provide ‘newer’ alternatives for raising NAD+ levels...
The reason that NAD IV therapy has an effect is because NAD can be broken down in circulation into NMN, and NMN to NR, which can then enter cells and work in ways that NA and NAM cannot. So the holistic, underground approach to NAD replenishment could have generated unique results and thrived.
But if that's right, then NR and NMN would represent new technologies that could deliver the same molecules to cells with much less trouble and expense.
That, in turn, would mean that IV therapy for NAD might just be an obsolete technology. IV NAD drips can cost 10x more than oral supplements, and no study shows injecting NAD into your veins is 10x better than simply taking orally the same precursors that your body might be generating in circulation.