b12 injection uses Shots at Home: How, Where & How Often to Inject Yourself B12 Shots & B12 Injections:

This means the B12 component in a compounded semaglutide formulation is most likely to help patients who are deficient or at risk of deficiency, those eating very little, those following plant-based diets, older adults whose B12 absorption decreases with age, or those with conditions affecting B12 absorption like gastric bypass or certain GI conditions

At first every

mcg and mg are units of measurement

The usual practice is for patients to simply turn up at the health centre where the nurse will have a supply of the injections which will be administered and there will be no cost incurred by the patient

The long half-life means you will still have drug on board even several days late