Calcitriol

Pronunciation

(kal si TRYE ole)

U.S. Brand Names

Calcijex®; Rocaltrol®

Synonyms

1,25 Dihydroxycholecalciferol

Generic Available

Yes

Canadian Brand Names

Rocaltrol®

Use

Management of hypocalcemia in patients on chronic renal dialysis; management of secondary hyperparathyroidism in moderate-to-severe chronic renal failure; management of hypocalcemia in hypoparathyroidism and pseudohypoparathyroidism

Use - Unlabeled/Investigational

Decrease severity of psoriatic lesions in psoriatic vulgaris; vitamin D resistant rickets

Pregnancy Risk Factor

C (manufacturer); A/D (dose exceeding RDA recommendation) (expert analysis)

Lactation

Enters breast milk/not recommended

Contraindications

Hypercalcemia; vitamin D toxicity; abnormal sensitivity to the effects of vitamin D; pregnancy (dose exceeding RDA)

Warnings/Precautions

Adequate dietary (supplemental) calcium is necessary for clinical response to vitamin D. Monitor serum calcium and phosphate concentrations; avoid hypercalcemia; calcium-phosphate product (serum calcium times phosphorus) must not exceed 70. Immobilization or excessive dosage may increase risk of hypercalcemia and/or hypercalciuria. Maintain adequate hydration. Use caution in patients with malabsorption syndromes (efficacy may be limited and/or response may be unpredictable).

Adverse Reactions

>10%: Endocrine & metabolic: Hypercalcemia (33%)

Frequency not defined:

Cardiovascular: Cardiac arrhythmia, hyper-/hypotension

Central nervous system: Headache, irritability, seizure (rare), somnolence, psychosis

Dermatologic: Pruritus, erythema multiforme

Endocrine & metabolic: Hypermagnesemia, hyperphosphatemia, polydipsia

Gastrointestinal: Anorexia, constipation, metallic taste, nausea, pancreatitis, vomiting, xerostomia

Hepatic: LFTs increased

Neuromuscular & skeletal: Bone pain, myalgia, dystrophy, soft tissue calcification

Ocular: Conjunctivitis, photophobia

Renal: Polyuria

Overdosage/Toxicology

Toxicity rarely occurs from acute overdose. Symptoms of chronic overdose include hypercalcemia, hypercalciuria with weakness, altered mental status, GI upset, renal tubular injury, and occasionally cardiac arrhythmias. Following withdrawal of the drug, treatment consists of bed rest, liberal fluid intake, reduced calcium intake, and cathartic administration. Severe hypercalcemia requires I.V. hydration and forced diuresis. I.V. saline may increase excretion of calcium. Calcitonin, cholestyramine, prednisone, sodium EDTA, biphosphonates, and mithramycin have all been used successfully to treat the more resistant cases of vitamin D-induced hypercalcemia. Use of peritoneal dialysis against a calcium-free dialysate has been reported.

Drug Interactions

Induces CYP3A4 (weak)

Cholestyramine, colestipol: May decrease absorption/effect of calcitriol.

Corticosteroids: May decrease hypercalcemic effect of calcitriol.

Digitalis: Risk of toxicity may be increased due to hypercalcemia from calcitriol. Monitor.

Magnesium-containing antacids: Toxicity may be increased by calcitriol. Avoid concurrent use.

Thiazide diuretics: May increase risk of hypercalcemia.

Stability

Store in tight, light-resistant container; calcitriol degrades upon prolonged exposure to light

Compatibility

Stable in D5W, NS, sterile water for injection

Mechanism of Action

Promotes absorption of calcium in the intestines and retention at the kidneys thereby increasing calcium levels in the serum; decreases excessive serum phosphatase levels, parathyroid hormone levels, and decreases bone resorption; increases renal tubule phosphate resorption

Pharmacodynamics/Kinetics

Onset of action: ~2-6 hours

Duration: 3-5 days

Absorption: Oral: Rapid

Protein binding: 99.9%

Metabolism: Primarily to 1,24,25-trihydroxycholecalciferol and 1,24,25-trihydroxy ergocalciferol

Half-life elimination: 3-8 hours

Excretion: Primarily feces; urine (4% to 6%)

Dosage

Individualize dosage to maintain calcium levels of 9-10 mg/dL

Renal failure:

Children:

Oral: 0.25-2 mcg/day have been used (with hemodialysis); 0.014-0.041 mcg/kg/day (not receiving hemodialysis); increases should be made at 4- to 8-week intervals

I.V.: 0.01-0.05 mcg/kg 3 times/week if undergoing hemodialysis

Adults:

Oral: 0.25 mcg/day or every other day (may require 0.5-1 mcg/day); increases should be made at 4- to 8-week intervals

I.V.: 0.5 mcg/day 3 times/week (may require from 0.5-3 mcg/day given 3 times/week) if undergoing hemodialysis

Hypoparathyroidism/pseudohypoparathyroidism: Oral (evaluate dosage at 2- to 4-week intervals):

Children:

<1 year: 0.04-0.08 mcg/kg once daily

1-5 years: 0.25-0.75 mcg once daily

Children >6 years and Adults: 0.5-2 mcg once daily

Vitamin D-dependent rickets: Children and Adults: Oral: 1 mcg once daily

Vitamin D-resistant rickets (familial hypophosphatemia): Children and Adults: Oral: Initial: 0.015-0.02 mcg/kg once daily; maintenance: 0.03-0.06 mcg/kg once daily; maximum dose: 2 mcg once daily

Hypocalcemia in premature infants: Oral: 1 mcg once daily for 5 days

Hypocalcemic tetany in premature infants: I.V.: 0.05 mcg/kg once daily for 5-12 days

Elderly: No dosage recommendations, but start at the lower end of the dosage range

Dosage adjustment for toxicity: Hypercalcemia: Adults:

Dialysis or hypoparathyroidism: Discontinue calcitriol and calcium supplements; initiate low-calcium diet. In dialysis patients with persistent hypercalcemia, may dialyze against calcium-free dialysate.

Predialysis:

Discontinue or reduce calcium supplements.

If taking calcitriol 0.5 mcg once daily, reduce to 0.25 mcg once daily.

If taking calcitriol 0.25 mcg once daily, discontinue until serum calcium normalizes. Restart at 0.25 mcg every other day.

Administration

May be administered without regard to food. Give with meals to reduce GI problems. May be administered as a bolus dose I.V. through the catheter at the end of hemodialysis.

Monitoring Parameters

Monitor symptoms of hypercalcemia (weakness, fatigue, somnolence, headache, anorexia, dry mouth, metallic taste, nausea, vomiting, cramps, diarrhea, muscle pain, bone pain and irritability). If patient becomes hypercalcemic on therapy, check serum calcium daily until normalized, then twice weekly on new dose. If hypercalcemia persists in predialysis patient, monitor PTH.

Reference Range

Calcium (serum) 9-10 mg/dL (4.5-5 mEq/L) but do not include the I.V. dosages; phosphate: 2.5-5 mg/dL

Test Interactions

Increased calcium, cholesterol, magnesium, BUN, AST, ALT, calcium (S), cholesterol (S); decreased alkaline phosphatase

Dietary Considerations

May be taken without regard to food. Give with meals to reduce GI problems.

Patient Education

Take exact dose as prescribed; do not increase dose. Maintain recommended diet and calcium supplementation. Avoid taking magnesium-containing antacids. You may experience nausea, vomiting, loss of appetite, or metallic taste (small, frequent meals, frequent mouth care, chewing gum, or sucking lozenges may help); or hypotension (use caution when rising from sitting or lying position or when climbing stairs or bending over). Report chest pain or palpitations; acute headache; skin rash; change in vision or eye irritation; CNS changes; unusual weakness or fatigue; persistent nausea, vomiting, cramps, or diarrhea; or muscle or bone pain. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to become pregnant. Breast-feeding is not recommended.

Dental Health: Effects on Dental Treatment

Key adverse event(s) related to dental treatment: Metallic taste and xerostomia (normal salivary flow resumes upon discontinuation).

Dental Health: Vasoconstrictor/Local Anesthetic Precautions

No information available to require special precautions

Mental Health: Effects on Mental Status

May cause sedation or irritability

Mental Health: Effects on Psychiatric Treatment

None reported

Dosage Forms

Capsule (Rocaltrol®): 0.25 mcg, 0.5 mcg [each strength contains coconut oil]

Injection, solution: 1 mcg/mL (1 mL); 2 mcg/mL (2 mL)

Calcijex®: 1 mcg/mL (1 mL)

Solution, oral (Rocaltrol®): 1 mcg/mL (15 mL) [contains palm seed oil]

References

Letsou AP and Price LS, "Health Aging and Nutrition: An Overview," Clin Geriatr Med , 1987, 3(2):253-60.

Myrianthopoulos M, "Dietary Treatment of Hyperlipidemia in the Elderly," Clin Geriatr Med , 1987, 3(2):343-59.

Riggs BL and Melton LJ, "The Prevention and Treatment of Osteoporosis," N Engl J Med , 1992, 327(9):620-7.

International Brand Names

Acuode® (CL); Alpha D!3® (RO); Altrical® (MX); Bocatriol® (AT, DE, DK); Calcijex® (AT, AU, BD, CH, CZ, ES, GB, HK, HR, HU, ID, IL, IT, LU, NL, NO, PL, RO, SE, SG, SI, TR); Calcitriol® (AR, CH, CO); Calcitriol KyraMed® (DE); Calcitriol-Nefro® (DE); Calcitriolo Teva® (IT); Calcitriol Purissimus® (AR); Decostriol® (DE); Dexiven® (AR); Difix® (IT); Hitrol® (ID); Kalcytriol® (PL); Kolkatriol® (ID); Lotravel® (AR); Osteo D® (SI); Osteotriol® (DE); Renatriol® (DE); Rexamat® (AR); Rocaltrol® (AT, AU, BD, BE, BR, CA, CH, CL, CZ, DE, DK, ES, FR, GB, HK, HR, HU, ID, IE, IT, JP, LU, MX, NL, NO, NZ, PL, PT, RO, RU, SE, SG, SI, TH, TR, YU, ZA); Roical® (SG); Rolsical® (IN); Silkis® (BE, CH, DE, FI, FR, GB, IE, NO, PL); Sitriol® (AU); Tirocal® (MX)

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