I think the thing I would worry about is turning your NAD+ powered into a sterile and safe injectable solution, mainly because I've never done such a thing.
Presumably you'd start with some bacteriostatic water, but the vials of bacteriostatic water I'm familiar with are sealed and really only appropriate for diluting a more concentrated also sterile liquid.
How do you start with a powder that probably is not itself sterile and get to your injectable solution? Please post the details as I have an interest in this.
And why IM rather than subq? A subq injection seems easier.
Anything injected into the body would ideally by first run through a 0.02 micron filter syringe, because most infectious agents are larger than 0.02 microns. Whatman Anotop is the only company that I know of that makes a 0.02 micron filter syringe.