Calm Logic said:
When it comes to pharma-grade B-12, South Korean product is probably the most reliable option. It beats compounded versions made in the US, and it's more dependable than the smaller Indian pharma outfits that export B-12 — especially regarding sterility and endotoxins.
There's a small Indian firm called Ocean Pharmaceutical that's gaining attention because it tests well for BAC, sterility and endos included. That means their B12 might be acceptable on the sterility front. They do offer cyanocobalamin ampules, at minimum. Still, those tests would need to be run again, and no B12 testing is happening at all. Given that, I'd personally feel better about a Korean source.
That said, research indicates oral supplements can match B12 injections over the long term. Injections tend to be reserved for acute or severe situations. In the US at least, requesting B12 bloodwork is something most doctors will agree to.