Classifications: vitamin d analog; Therapeutic: vitamin d analog
Pregnancy Category: C
0.25 mcg, 0.5 mcg tablets; 1 mcg/mL oral solution; 1 mcg/mL, 2 mcg/mL injection
Synthetic form of an active metabolite of ergocalciferol (vitamin D2). In the liver, cholecalciferol (vitamin D3) and ergocalciferol (vitamin D2) are enzymatically metabolized to calcifediol, an activated form of vitamin D3. Calcifediol is biodegraded in the kidney to calcitriol, the most potent form of vitamin D3. Patients with nonfunctioning kidneys are unable to synthesize sufficient calcitriol.
By promoting intestinal absorption and renal retention of calcium, calcitriol elevates serum calcium levels, decreases elevated
blood levels of phosphate and parathyroid hormone, and decreases subperiosteal bone resorption and mineralization defects.
Management of hypocalcemia in patients undergoing chronic renal dialysis and in patients with hypoparathyroidism or pseudohypoparathyroidism.
Selected patients with vitamin Ddependent rickets, familial hypophosphatemia (vitamin Dresistant rickets); management
of hypocalcemia in premature infants.
Hypercalcemia or vitamin D toxicity; pregnancy (category C).
Hyperphosphatemia, renal failure; elderly; sarcoidosis; patients receiving digitalis glycosides.
Route & Dosage
Adult: PO 0.25 mcg/d, may be increased by 0.25 mcg/d q48wk for dialysis patients or q24wk for hypoparathyroid patients
if necessary IV 0.5 mcg 3 times/wk at the end of dialysis, may need up to 3 mcg 3 times/wk
Child: PO On hemodialysis: 0.252 mcg/d IV 0.010.05 mcg/kg 3 times/wk PO Renal failure without dialysis: 0.0140.041 mcg/kg/d
- Oral dose can be taken either with food or milk or on an empty stomach. Discuss with physician.
- When given for hypoparathyroidism, the dose is given in the morning.
- Capsules should be protected from heat, light, and moisture. Store in tightly closed container.
PREPARE: Direct: Give undiluted.
ADMINISTER: Direct: Give IV push over 3060 sec.
Adverse Effects (≥1%)Body as a Whole:
Muscle or bone pain. CV:
Anorexia, nausea, vomiting, dry mouth, thirst, constipation
, abdominal cramps, metallic taste. Metabolic:
Vitamin D intoxication, hypercalcemia, hypercalciuria, hyperphosphatemia. CNS:
Headache, weakness. Special Senses:
Blurred vision, photophobia. Urogenital:
InteractionsDrug: thiazide diuretics
may cause hypercalcemia; calcifediol-induced hypercalcemia may precipitate digitalis arrhythmias in patients receiving
Readily absorbed from GI tract. Onset:
26 h. Peak:
1012 h. Duration:
35 d. Metabolism:
In liver. Elimination:
Mainly in feces. Half-Life:
Assessment & Drug Effects
- Lab tests: Determine baseline and periodic levels of serum calcium, phosphorus, magnesium, alkaline phosphatase, creatinine;
measure urinary calcium and phosphorus levels q24h.
- Effectiveness of therapy depends on an adequate daily intake of calcium and phosphate. The physician may prescribe a calcium
supplement on an as-needed basis.
- Monitor for hypercalcemia (see Signs & Symptoms, Appendix F). During dosage adjustment period, monitor serum calcium levels
particularly twice weekly to avoid hypercalcemia.
- If hypercalcemia develops, withhold calcitriol and calcium supplements and notify physician. Drugs may be reinitiated when
serum calcium returns to normal.
Patient & Family Education
- Discontinue the drug if experiencing any symptoms of hypercalcemia (see Appendix F) and contact physician.
- Do not use any other source of vitamin D during therapy, since calcitriol is the most potent form of vitamin D3. This will avoid the possibility of hypercalcemia.
- Consult physician before taking an OTC medication. (Many products contain calcium, vitamin D, phosphates, or magnesium, which
can increase adverse effects of calcitriol.)
- Maintain an adequate daily fluid intake unless you have kidney problems, in which case consult your physician about fluids.