Class and Category

Pharmacologic Class: Vitamin D analogue
Therapeutic Class: Antihypocalcemic

Indications and Dosages
To treat hypocalcemia in dialysis patients.

Capsules and Oral Solutions
Initial: 0.25 mcg daily. Increased by 0.25 mcg daily every 4 to 8 wk, if needed to achieve normal serum calcium level.
Maintenance: 0.5 to 1 mcg daily.

I.V. Injection
Initial: 0.25 mcg every other day, 3 times/wk given rapidly at end of dialysis. Increased by 0.25 mcg or 0.5 mcg at 2- to 4-wk intervals, if needed.
Usual: 0.5 mcg to 3 mcg 3 times a wk.

To treat hypocalcemia in predialysis patients
Capsules and Oral Solutions
Adults and children age 3 and over:  
Initial: 0.25 mcg daily. Increased after 4 to 8 wk, if needed, to 0.5 mcg daily.

Oral Solution
Children up to age 3: 10 to 15 ng/kg daily.

To treat hypoparathyroidism
Capsules and Oral Solutions
Adults and children age 6 and over:  
Initial: 0.25 mcg daily in the morning. Increased every 2 to 4 wk, if needed, to achieve normal serum calcium level.
Usual: 0.5 to 2 mcg daily.
Children ages 1 to 5:
0.25 to 0.75 mcg daily in the morning.

Mechanism of Action
Binds to specific receptors on intestinal mucosa to increase calcium absorption from the intestine. The drug may also regulate calcium ion transfer from bone to blood and stimulate calcium reabsorption in the distal renal tubules, making more calcium available in the body.

Hypercalcemia, hypersensitivity to calcitriol or its components, vitamin D toxicity. 

Calcium Supplements: Increased risk of hypercalcemia
Cholestyramine: Decreased calcitriol absorption
Corticosteroids: Possibly inhibits calcium absorption
Digitalis Glycosides: Possibly arrhythmias
Ketoconazole: Decreased calcitriol level
Magnesium-containing antacids Hypermagnesemia Mineral oil: Decreased blood calcitriol level (with prolonged use of mineral oil)
Phenobarbital, Phenytoin: Decreased synthesis and blood level of calcitriol
Phosphate-binding Agents: Possibly altered phosphate transport in bone, intestine, and kidneys
Thiazide Diuretics: Hypercalcemia
Vitamin D: Additive effects, including possible hypercalcemia


Adverse Reactions
Skin: Erythema multiforme, lip swelling, pruritus, rash, urticaria
Other: Anaphylaxis

Childbearing Considerations
  • It is not known if drug can cause fetal harm. However, upon birth, the neonate may exhibit mild signs and symptoms of hypercalcemia for several days.
  • Use with caution only if benefit to mother outweighs potential risk to fetus.

  • Drug may be present in breast milk.
  • Breastfeeding should not be done during drug therapy

Nursing Considerations
  • Check to be sure patient receives enough calcium.
  • Store drug at room temperature, and protect from heat and direct light.
  • Monitor patient closely. In high-dose or long-term calcitriol therapy, be alert for vitamin D toxicity. Early evidence includes abdominal or bone pain, constipation, dry mouth, headache, metallic taste, myalgia, nausea, somnolence, vomiting, and weakness. Late evidence includes albuminuria, anorexia, arrhythmias, azotemia, conjunctivitis (calcific), decreased libido, elevated AST and ALT levels, elevated BUN level, vascular calcification, hypercholesterolemia, hypertension, hyperthermia, irritability, mild acidosis, nephrocalcinosis, nocturia, pancreatitis, photophobia, polydipsia, polyuria, pruritus, rhinorrhea, and weight loss.

  1. Warn the patient not to take other forms of vitamin D while taking calcitriol.
  2. Instruct the patient to take a missed dose as soon as possible.
  3. Advise patient to notify prescriber immediately about possible toxicity, such as headache, irritability, nausea, photophobia, vomiting, weakness, and weight loss.

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