The schedule

The usual shape is a loading run then a holding dose: 1000 mcg once a week for four to eight weeks to refill the stores, then 1000 mcg once a month for as long as the reason for the shortage lasts. From a 10 mL vial at 1000 mcg per mL, one dose is 1 mL, which is 100 units on a U-100 insulin syringe. Pick one day of the week and keep it, because missing a loading dose simply stretches the refill out. When the cause is permanent, such as missing intrinsic factor, the monthly dose does not stop.