Vitamin D (courtesy of Jenny Cole)

Different Vitamin D forms:

vitamin D precursor: Ergocalciferol (Drisdol) (vitamin D2)

active vitamin D: Calcitriol (Rocaltrol - oral) (Calcijex - iv) (preferred in pts with end stage renal disease)

vitamin D analogs: paricalcitol (Zemplar - iv)
doxercalciferol (Hectoral -po or iv)

Vitamin D analogs offer an alternative for pts in whom persistent hypercalcemia develops with calcitriol therapy.

A bit of trivia: vitamin D2 is the form added to milk

Another bit of trivia...I know you are on the edge of your seat....vitamin D has to go through 2 enzymatic hydroxylations to get to its active form. The first hydroxylation is in the liver and the second is in the kidney where it is converted to calcitriol whose main function is to regulate calcium by enhancing calcium absorption in the small intestine and increases calcium and phosphorus reabsorption in the kidney.