fda bpc-157 unapproved new drug scientists flag concerns with peptides as RFK Jr. tries to ease access : NPR 7 peptides under FDA review:

Keep secure and out of reach of individuals not authorized for this specific research project

Toohey JI: Vitamin B12 and methionine synthesis: A critical review

Animal doses cannot be directly extrapolated to humans Key Research Findings# Selective and membrane-permeable small molecule inhibitors of nicotinamide N-methyltransferase reverse high fat diet-induced obesity in mice , published in Biochemical Pharmacology (Neelakantan H et al., 2018

Before you can go ahead with getting a vitamin b12 shot, you will need a prescription from a licensed doctor who can confirm your needs and the dosage your body requires