What it does is reduce local inflammation, support the maintenance of remaining tissue, and in some cases improve synovial health in a way that changes the pain experience meaningfully
If you get a B12 injection and it stings, that means it's not just B12
Intrinsic factor binds to vitamin B12, so that you can absorb it into the blood
The dose of 2000 micrograms of B12 is more than 800 times the recommended daily amount so, on the face of it, this dose seems too high, but as you increase the amount of B12 in your diet, less of a percentage will be absorbed
doi:10.1042/bse0340139
Stability in any given laboratory still depends on temperature, pH, light exposure, and freeze-thaw history all of which should be documented per lot