Action and metabolism of dihydrotachysterol2.

Dihydrotachysterol2 (DHT2) is a synthetic analogue of vitamin D2. DHT2 is used extensively in the treatment of renal osteodystrophy and hypoparathyroidism. It is equally efficacious as 1 alpha,25-dihydroxyvitamin D3 and 1 alpha-hydroxyvitamin D3. Moreover, it offers interesting therapeutical advantages and it is surprising that until recently little was known of its metabolism and sites of action. This paper deals with studies on the pharmacology of DHT2 in rats. Following the synthesis of [3H]DHT2 and oral administration, evidence was obtained that DHT2 is metabolized extensively; three of the major metabolites could be identified as 25-hydroxy-DHT2, 1 alpha,25- and 1 beta,25-dihydroxy-DHT2.