Intramuscular vs Subcutaneous Parenteral administration of vitamin B-12 via injection has been standard protocol for decades, according to the Centers for Disease Control and Prevention
b12deficiency.info/ B12 books I found useful "What You Need to Know About Pernicious Anaemia and Vitamin B12 Deficiency" by Martyn Hooper Martyn Hooper is the chair of PAS (Pernicious Anaemia Society)
Generic Name: Vitamins B1 + B6 + B12 (Thiamine + Pyridoxine + Cyanocobalamin)
Rajpathak SN, Gunter MJ, Wylie-Rosett J, Ho GYF, Kaplan RC, Muzumdar R, Rohan TE, Strickler HD
Ready To Get Started With Injectable Vitamin & Amino Acid Therapy
Preservation requirements Water-based formulations support microbial growth