Vitamins constitute a comprehensive group of therapeutic and prophylactic preparations. Before classifying any product it is important to be familiar with the main subdivision of the group.
It may be necessary to consider whether a product is a vitamin preparation with iron or an iron preparation with vitamins, a mineral preparation with vitamins or a vitamin preparation with minerals, or if the product should be regarded as a tonic etc. As an aid to such considerations, guidelines are given at each sublevel.
Vitamin B12 is classified in B03 - Antianemic preparations.
Vitamin K is classified in B02 - Antihemorrhagics.
Vitamins administered as i.v. solution additives, see B05XC.
Some definitions:
Multivitamins: Products containing minimum vitamins A, B, C and D. One B-vitamin is sufficient.
B-complex: Products containing minimum thiamine, riboflavine, pyridoxine, nicotinamide. The products may contain other B-vitamins.

Combinations with trace elements are allowed. Other combinations, see A11J - Other vitamin products, combinations.
See also A12 - Mineral supplements.

Vitamin D and analogues may be regarded as hormones, but are classified in this group. Calcium homeostasis, see H05.
Paricalcitol indicated for the prevention and treatment of secondary hyperparathyroidsm is classified here.