[Falecalcitriol as a new therapeutic agent for secondary hyperparathyroidism].

The 26 and 27 positions of vitamin D molecular structure of calcitriol were fluorinated with 3 atoms of fluorine each and the new compound was named falecalcitriol (F6). This new compound was found to be 10 to 100 times more active compared with calcitriol depending on the target organs. As a mechanism of strong action of F6 it was discovered that F6 is hydroxylated at 23 position which has almost the same activity as the mother compound. It was also demonstrated that the PTH suppressive effect was relatively stronger than the calcium absorption action from the intestine. Thus F6 was authorized to be applied to the treatment of secondary hyperparathyoroidism in hemodialysed patients as well as to the treatment of hypoparathyroidism.