First, the benzyl alcohol begins to degrade
The debate is more reasonable than it looks: the 28 days is not printed on the label, it is the default beyond-use date USP General Chapter 797 assigns to any opened multi-dose vial
Contact a healthcare provider if you notice: Persistent or worsening neuropathy symptoms, such as tingling, numbness, burning pain, or weakness New or unusual side effects, including skin rash, itching, or acne-like breakouts Possible medication interactions, especially if you take metformin, acid-reducing medications, or other long-term prescriptions Changes in neurological function, such as balance issues, confusion, memory changes, or worsening coordination Recognizing these warning signs early helps prevent complications and supports better long-term nerve health outcomes
The answer: thats correct, because 20,000mcg 2mL = 10,000mcg/mL
The biology is interesting enough that ongoing research is warranted, and I'm watching the human trial literature carefully