Agonists of the vitamin D receptor are used to suppress parathyroid hormone (PTH) synthesis and secretion in the treatment of hyperparathyroidism associated with renal failure. 22-Oxacalcitriol is an analog of calcitriol that, like calcitriol, is a receptor-active form of vitamin D3 which effectively blocks PTH synthesis. First reported to avoid hypercalcemia, an undesirable side effect of calcitriol, prolonged treatment with 22-oxalcalcitriol can be calcemic in humans. Analogs of calcitriol, including 22-oxacalcitriol, inhibit human keratinocyte proliferation while inducing differentiation and is beneficial in treating psoriasis. 22-Oxacalcitriol also blocks the proliferation while inducing differentiation and apoptosis of certain tumor cells.
