Compared to such native
vitamin D agents as
cholecalciferol (D3), egocalciferol (D2), and
calcifediol (25- hydroxy
vitamin D3, which need 1-alpha
hydroxylase to be activated, 1-alpha-
ergocalciferol, also known as
doxercalciferol, is a synthetically manufactured
vitamin D analog used for treatment of
secondary hyperparathyroidism (SHPT) in
chronic kidney disease (CKD).
Doxercalciferol exhibits more structural similarities to plant-based
vitamin D2,
ergocalciferol, than with animal-based
vitamin D3,
cholecalciferol. Because
doxercalciferol does not have a 25-hydroxy group, it requires 25-hydroxylation by the liver to be activated, a process independent of kidneys.
Doxercalciferol shares these features with its D3 equivalent, 1-alpha-hydroxy-
cholecalciferol (
alphacalcidol), both of which are activated hepatically and independent of renal or extra-renal 1-alpha
hydroxylase. In experimental and clinical studies of CKD and SHPT,
doxercalciferol effectively reduces
parathyroid hormone levels and restores abnormal bone pathology. The efficacy of
doxercalciferol is similar to other
vitamin D analogs including
calcitriol,
alphacalcidol,
paricalcitol (19-nor-1,25-dihydroxyvitamin D2 ) and
maxacalcitol (1,25-dihydroxy-22-oxa-
vitamin D3). The frequency and magnitude of
hypercalcemia or
hyperphosphatemia observed with
doxercalciferol treatment may be less than
calcitriol or
alphacalcidol therapy but not less than such
vitamin D-mimetics as
paricalcitol or
maxacalcitol.
Doxercalciferol can be used for the treatment of SHPT across all ranges of CKD, particularly if
hypercalcemia is of concern. There are limited data as to whether
doxercalciferol confers greater efficacy or better outcome and survival than other
vitamin D analogs and D-mimetics. Whereas further studies are warranted,
doxercalciferol can safely be used for correction of SHPT in the entire spectrum of CKD.