b12 injection is given where Instruction Guide for Intramuscular (IM) Self-injection of Methylcobalamin 1mg/5mg Treating Severe Vitamin B12 Deficiency

The good news is that some people notice improvements within a few days, particularly if they have a significant deficiency

Certain medications The following drugs can reduce levels of vitamin B12 in your body: Antibiotics -- long-term use can lower vitamin B levels generally Anti-seizure drugs Chemotherapy medicines, especially methotrexate Drugs used to reduce stomach acid, like H2 blockers (Pepcid AC, Tagamet, Zantac) and proton pump inhibitors (Nexium, Prevacid, Prilosec) Metformin (Glucophage) -- taken for diabetes Colchicine -- taken for gout Some cholesterol-lowering medications Other causes You're over 65

Skeletal muscle ageing models preclinical investigation has explored NNMT inhibition in models of age-related muscle dysfunction and stem-cell quiescence

doi: 10.1136/pgmj.2006.048132