Vitamin D aids in the absorption of calcium and has central roles in bone formation and maintenance, hypertension, cancer, and immunity. 1-Hydroxy Vitamin D3 is a synthetic prodrug which is converted by cytochrome P450 isoforms to the vitamin D receptor agonist 1,25-dihydroxy vitamin D3 in vivo. Such prodrugs are effective in suppressing the synthesis and secretion of parathyroid hormone in secondary hyperparathyroidism, an action which requires the vitamin D receptor. 1-Hydroxy Vitamin D3 supports bone growth both in postmenopausal women and in glucocorticoid-induced osteoporosis. It also provides renal and cardiovascular protection during chronic kidney disease.
1.Biological effects of various regimes of 25-hydroxyvitamin D3 (calcidiol) administration on bone mineral metabolism in postmenopausal women". Clin Cases Miner Bone Metab. 6 (2): 169–173. 2009. PMC 2781231 Freely accessible. PMID 22461169.