Dosing and uses of Hectorol (doxercalciferol)
Adult dosage forms and strengths
capsule
- 0.5mcg
- 2.5mcg
injectable solution
- 2mcg/mL
Dialysis
Intial dose
- 10 mcg PO 3 times/week at dialysis, may increase by 2.5 mcg/dose, no more than 20 mcg/dose 3 times/week OR
- 4 mcg IV bolus 3 times/week following dialysis, may increase by 1-2 mcg/dose q8Weeks
Dose Modifications
- If intact parathyroid hormone (iPTH) <100 pg/mL, withhold for 1 week; then reinitiate at reduced dose of at least 2.5 mcg PO lower than last dose or at least 1 mcg IV lower than last dose
- Reduce dose or stop the drug if Ca x P product >75 mg²dL²; if interrupted, reinitiate at lower doses as above
- Monitor: Serum Ca & phosphorus, iPTH
Pre-dialysis
Initial: 1 mcg PO qDay, may increase by 0.5 mcg/dose q2Weeks
Reduce or interrupt dose if iPTH concentration falls or Ca x P >55 mg²/dL² (consult package insert); reinitiate at least 0.5 mcg lower than last dose
Renal Impairment
Dose adjustment not necessary
Hepatic Impairment
Caution; guidelines not available
Other Indications & Uses
Secondary hyperparathyroidism associated with chronic kidney disease
Pediatric dosage forms and strengths
Safety & efficacy not established
Hectorol (doxercalciferol) adverse (side) effects
Frequency not defined
Edema
Palpitation
Chills
Dizziness
Headache
Malaise
Nausea
Vomiting
Hypercalcemia
Hypercalciuria
Anorexia
Constipation
Dyspepsia
Arthralgia
Edema
Weight increase
Sleep disorder
Dyspnea Pruritus
Postmarketing Reports
Hypersensitivity reactions (patients on hemodialysis)
Warnings
Contraindications
Hypersensitivity
Hypercalcemia, hyperphosphatemia, hypervitaminosis d
Cautions
Monitor serum Ca & phosphorus frequently; reduce dose or stop the drug if Ca x P product >75 mg²/dL²
Acute hypercalcemia may exacerbate tendencies for cardiac arrhythmias and seizures and may potentiate action of digitalis drugs; chronic hypercalcemia can lead to generalized vascular calcification and other soft-tissue calcification; in chronic kidney disease maintain Ca x P product at <55 mg²/dL²
Use with caution in patients receiving digitalis; digitalis toxicity is potentiated by hypercalcemia
Decrease dose if hypercalcemia or hyperphosphatemia occurs
Serious hypersensitivity reactions, including fatal outcome, in patients on hemodialysis, reported post marketing; hypersensitivity reactions include anaphylaxis with symptoms of angioedema (involving face, lips, tongue and airways), hypotension, unresponsiveness, chest discomfort, shortness of breath, and cardiopulmonary arrest; reactions may occur separately or together
Use oral calcium-based or other non-aluminum-containing phosphate binders and a low phosphate diet to control serum phosphorus levels in patients undergoing dialysis
Pregnancy and lactation
Pregnancy category: B
Lactation: excretion in milk unknown/not recommended
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Hectorol (doxercalciferol)
Mechanism of action
Doxercalciferol is metabolized to the active form of vitamin D, which in turn controls the reabsorption of calcium by the kidneys, controls the intestinal absorption of dietary calcium, and along with parathyroid hormone controls the mobilization of calcium from the skeleton.
Absorption
Onset: IV: 10-12 wk, PO: 3-4 months
Peak Plasma Time: 8-12 hr
Metabolism
Metabolism: in liver to hepatic vitamin D 25-hydroxylases to 1,25-dihydroxyvitamin D2 (active)
Metabolites: 1,25-dihydroxyvitamin D2 (active), responsible for most of metabolic effects of doxercalciferol and 1,24-dihydroxyvitamin D2 (minor metabolite)
Elimination
Half-Life: 32-37 hr (active metabolite 1,25-dihydroxyvitamin D2)
Dialyzable: No (HD)
Administration
Administration
IV bolus
