Zemplar

paricalcitol

(par-i-kal-si-tole) paricalcitol,

Zemplar

(trade name)

Classification

Therapeutic: vitamins
Pharmacologic: fat soluble vitamins
Pregnancy Category: C

Indications

Prevention and treatment of secondary hyperparathyroidism in patients with Stage 3 or 4 (PO) or Stage 5 (PO and IV) chronic kidney disease.

Action

Paricalcitol is a synthetic analog of calcitriol (the active form of vitamin D3.Promotes the absorption of calcium and decreases parathyroid hormone concentrations.

Therapeutic effects

Improved calcium and phosphorous homeostasis in patients with chronic kidney disease.

Pharmacokinetics

Absorption: IV administration results in complete bioavailability; well absorbed following oral administration.Distribution: Crosses the placenta.Protein Binding: 99.9%.Metabolism and Excretion: Primarily metabolized by the liver and excreted via hepatobiliary elimination.Half-life: 14–20 hr.

Time/action profile

ROUTEONSETPEAKDURATION
POunknown2–4 wkunknown
IVunknown2–4 wkunknown

Contraindications/Precautions

Contraindicated in: Hypersensitivity; Hypercalcemia; Vitamin D toxicity; Lactation: Lactation.Use Cautiously in: Concurrent use of digoxin; Obstetric: Safety not established.

Adverse Reactions/Side Effects

Seen primarily as manifestations of toxicity (hypercalcemia)

Central nervous system

  • dizziness
  • headache
  • somnolence
  • weakness

Ear, Eye, Nose, Throat

  • conjunctivitis
  • photophobia
  • rhinorrhea

Cardiovascular

  • arrhythmias
  • edema
  • hypertension
  • palpitations

Gastrointestinal

  • anorexia
  • constipation
  • diarrhea
  • dry mouth
  • ↑ liver function tests
  • metallic taste
  • nausea
  • polydipsia
  • vomiting
  • weight loss

Genitourinary

  • albuminuria
  • azotemia
  • ↓ libido

Dermatologic

  • pruritus
  • rash

Endocrinologic

  • gout

Fluid and Electrolyte

  • hypercalcemia

Metabolic

  • hyperthermia

Musculoskeletal

  • bone pain
  • metastatic calcification
  • muscle pain

Interactions

Drug-Drug interaction

Cholestyramine, colestipol, or mineral oil ↓ absorption of vitamin D analogues.Use with thiazide diuretics may result in hypercalcemia.Corticosteroids ↓ effectiveness of vitamin D analogues.Use with digoxin may ↑ risk of arrhythmias if hypercalcemia occurs.Concurrent use of magnesium-containing drugs may lead to hypermagnesemia.Calcium-containing drugs may ↑ risk of hypercalcemia.Concurrent use of other vitamin D supplements ↑ risk of hypercalcemia; avoid use of prescription doses of vitamin D.Agents that induce CYP3A4 (phenobarbital, rifampin ) and agents that inhibit CYP3A4 (atazanavir, clarithromycin, erythromycin, indinavir, itraconazole, ketoconazole, nefazodone, nelfinavir, ritonavir, saquinavir, verapamil, voriconazole ) may alter requirements for paricalcitol (monitoring of calcium and phosphorus recommended).Aluminum-containing drugs may ↑ aluminum levels and risk of aluminum bone toxicity; avoid concurrent use.Ingestion of foods high in calcium content (see ) may lead to hypercalcemia.

Route/Dosage

Stage 3 or 4 Chronic Kidney DiseaseOral (Adults) Baseline intact PTH (iPTH) concentration ≤500 pg/mL—Initiate with 1 mcg/day or 2 mcg 3 times weekly; dose can be adjusted at 2–4 wk intervals based on iPTH, calcium, and phosphate concentrations; Baseline iPTH concentration >500 pg/mL—Initiate with 2 mcg/day or 4 mcg 3 times weekly; dose can be adjusted at 2–4 wk intervals based on iPTH, calcium, and phosphate concentrations.Stage 5 Chronic Kidney DiseaseOral (Adults) Initial dose (in mcg) is based on following equation: baseline iPTH concentration (pg/mL)/80; dose should be given 3 times weekly; dose can be adjusted at 2–4 wk intervals based on iPTH, calcium, and phosphate concentrations.Intravenous (Adults and Children ≥5 yr) 0.04–0.1 mcg/kg 3 times weekly during dialysis; dose can be adjusted by 2–4 mcg at 2–4 wk intervals based on iPTH, calcium, and phosphate concentrations (doses up to 0.24 mcg/kg have been used).

Availability (generic available)

Capsules: 1 mcg, 2 mcg, 4 mcg Injection: 2 mcg/mL, 5 mcg/mL

Nursing implications

Nursing assessment

  • Assess for symptoms of vitamin deficiency prior to and periodically during therapy.
  • Assess patient for bone pain and weakness prior to and during therapy.
  • Observe patient carefully for evidence of hypocalcemia (paresthesia, muscle twitching, laryngospasm, colic, cardiac arrhythmias, and Chvostek’s or Trousseau’s sign). Protect symptomatic patient by raising and padding side rails; keep bed in low position.
  • Lab Test Considerations: Oral—Serum calcium, phosphorus, and iPTH concentrations should be monitored at least every 2 wk for the first 3 mo of therapy or following any dose adjustment, then monthly for 3 mo, then every 3 mo.
    • IV—Serum calcium and phosphorus concentrations should be monitored twice weekly initially until dose stabilized and then at least monthly. Serum iPTH concentrations should be monitored every 3 mo.
    • The serum calcium times phosphate product (Ca X P) should not exceed 70 mg2/dL2 (patients may be at ↑ risk of calcification).
    • Toxicity is manifested as hypercalcemia, hypercalciuria, and hyperphosphatemia. Assess patient for appearance of nausea, vomiting, anorexia, weakness, constipation, headache, bone pain, and metallic taste. Later symptoms include polyuria, polydipsia, photophobia, rhinorrhea, pruritus, and cardiac arrhythmias. Notify health care professional immediately if these signs of hypervitaminosis D occur. Treatment usually consists of discontinuation of paricalcitol, a low-calcium diet, use of low-calcium dialysate in peritoneal dialysis patients, or administration of a laxative. IV hydration and loop diuretics may be ordered to increase urinary excretion of calcium. Hemodialysis may also be used.

Potential Nursing Diagnoses

Imbalanced nutrition: less than body requirements (Indications)

Implementation

  • Administer by rapid injection through the catheter at the end of a hemodialysis period.

Patient/Family Teaching

  • Advise patient to take medication as directed. Take missed doses as soon as remembered that day, unless almost time for next dose; do not double up on doses.
  • Review diet modifications with patient. See for foods high in calcium and vitamin D. Renal patients must still consider renal failure diet in food selection. Health care professional may order concurrent calcium supplement.
  • Encourage patient to comply with dietary recommendations of health care professional. Explain that the best source of vitamins is a well-balanced diet with foods from the 4 basic food groups and the importance of sunlight exposure. See for foods high in vitamin D.
  • Patients self-medicating with vitamin supplements should be cautioned not to exceed RDA. The effectiveness of megadoses for treatment of various medical conditions is unproved and may cause side effects.
  • Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.
  • Advise patient to avoid concurrent use of antacids containing magnesium.
  • Review symptoms of hypercalcemia (feeling tired, difficulty thinking clearly, loss of appetite, nausea, vomiting, constipation, increased thirst, increased urination and weight loss) and instruct patient to report these promptly to health care professional.
  • Emphasize the importance of follow-up exams to evaluate progress.

Evaluation/Desired Outcomes

  • Normalization of serum calcium and parathyroid hormone levels.

Zemplar®

Paricalcitol Endocrinology A synthetic vitamin D for preventing and treating 2º hyperparathyroidism due to chronic renal failure. See Hyperparathyroidism.