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Medical Term:


Pronunciation: er'go-kal-sif'er-ol


Activated ergosterol, the vitamin D of plant origin; it arises from ultraviolet irradiation of ergosterol, which is cleaved at the 9,10 bond and develops a double bond between C-10 and C-19; used in prophylaxis and treatment of vitamin D deficiency.

Synonym(s): calciferol, ercalciol, viosterol, vitamin D2

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