Just received glutathione 600 and NAD 500

nice and what strength are you mixing to in mg per ml

I didn’t choose them actually. They are meant for others and I am only testing the vials.

I spent a long time on precursor supplements before injections became common. The two approaches are not direct replacements though. Direct administration can give a quicker noticeable effect because it skips some conversion steps. From what I have seen glutathione is actually my favorite of everything I have tried mainly because I get an immediate lift from it that precursors alone have never given me. Do you have to inject them? No. You can use NAC and glycine to help your body make glutathione and various B3 forms to support NAD. Vitamin C helps the antioxidant side too. Still I choose the injections because I simply feel better on them and I would rather do two shots than add four or more orals to my routine. My pill organizer is already full. I posted a longer version of this thought earlier.

Thanks for being straightforward. If the lift helps you feel better that is fine. We can agree it is not really about bioavailability or going past a controlled biological limit right?

No we are not in agreement on that. Bioavailability is definitely part of why the results differ. Different routes can create very different peak levels and immediate effects even if the body eventually regulates the compounds. How the substance moves through the system matters for any compound.

As you note it comes down to kinetics. Availability relates to concentrations so it is mostly about dynamics. In other words it changes how fast the first peak arrives. It is like accelerating quickly when the light changes but that does not matter if speed is capped later anyway.

You are correct that concentration affects the dynamic results and that reaching a peak faster does not automatically make something more useful depending on the compound. Where I differ is with the idea that bioavailability is therefore mainly about dynamics and with boiling the route difference down to just how fast the first peak happens. To be clear bioavailability is a pharmacokinetic idea not a pharmacodynamic one. It covers both the speed and the total amount that becomes available not only concentration. The route can change Tmax how fast the peak occurs Cmax how high it gets AUC total exposure over time the full concentration curve and how long exposure lasts. The traffic light comparison would only hold if every route produced identical results for all those measures but they often do not and those differences can matter. One route is not automatically right wrong better or worse.

Regarding impacts, pills can produce body-wide levels but there's no way to calculate an equivalent pill amount that matches a shot's highest blood concentration. Beyond just the maximum level the full exposure across time also counts so ramping up pills won't make the approaches match.
I'm not sure the pill version always costs less when reliable sources matter. A basic supplement runs high for a month and layering in other items like antioxidants amino acids and special forms adds up fast.
These items lack drug-level rules so counterfeits show up often and source materials usually come from abroad anyway. For my own use I pick pharma-grade shots of one antioxidant plus verified versions of the coenzyme from my source instead of typical online options.
I started with pills then switched to shots once the first method showed little effect which suited me.