american regent cyanocobalamin b12 injection usp Product Catalog Vitamin B-12 Cyanocobalamin
1000 mcg
Description
Vitamin B12 is primarily found in animal-based foods such as meat, dairy, and eggs

The injection would be given slowly into a vein, or added to an IV drip
If you are new to GLP-1 medications, or if you have not taken one in some time, you will begin at Tier 1

And its one where the chemistry gives a clearer answer than most compounds in this space