DARBEPOETIN ALFA

DARBEPOETIN ALFA
(dar-be-po-e'tin)
ARANESP
Classifications: blood former; hematopoietic growth factor;
Therapeutic:human erythropoietin
; antianemic
Prototype: Epoetin alfa
Pregnancy Category: C

Availability

25 mcg/mL, 40 mcg/mL, 60 mcg/mL, 100 mcg/mL, 150 mcg/mL, 200 mcg/mL, 300 mcg/mL, 500 mcg/mL vials; 40 mcg/0.4 mL, 60 mcg/0.3 mL, 100 mcg/0.5 mL, 150 mcg/0.3 mL, 200 mcg/0.4 mL, 300 mcg/0.6 mL, 500 mcg/mL syringe

Action

An erythropoiesis-stimulating protein closely related to human erythropoietin. Erythropoietin is produced naturally in the kidney in response to hypoxia, and stimulates red blood cell production in the bone marrow. Production of endogenous erythropoietin is impaired in patients with chronic renal failure (CRF) resulting in anemia.

Therapeutic Effect

Darbepoetin stimulates release of reticulocytes from the bone marrow into the blood stream where they mature into RBCs.

Uses

Treatment of anemia in patients with chronic renal failure or chemotherapy-associated anemia, treatment of chemotherapy-induced anemia in nonmyeloid malignancies.

Contraindications

Patients with uncontrolled hypertension; hypersensitivity to darbepoetin or human albumin; pregnancy (category C).

Cautious Use

Controlled hypertension, elevated hemoglobin, folic acid or vitamin B12 deficiencies, infections, inflammatory or malignant processes, osteofibrosis, occult blood loss, hemolysis, severe aluminum toxicity, bone marrow fibrosis, chronic renal failure patients not on dialysis, lactation, hematologic diseases.

Route & Dosage

Anemia
Adult: IV/SC Initially, 0.45 mcg/kg once/wk. Reduce dose by 25% if there is a rapid increase (i.e., more than 1 g/dL in any 2-wk period) in Hgb or if the Hgb is approaching 12 g/dL. If the Hgb does not increase by 1 g/dL after 4 wk of therapy and iron stores are adequate, increase the dose  by 25%. Maintenance dose is 0.26–0.65 mcg/kg once/wk

Converting Epoetin Alfa to Darbepoetin
Adults: IV/SC Estimate the starting dose of darbepoetin alfa based on the total weekly dose of  epoetin alfa at the time of conversion. If the patient was receiving epoetin alfa 2–3 times/wk, administer darbepoetin alfa once per week; if the patient was receiving epoetin alfa once per week, administer darbepoetin alfa once every 2 wk. The route of administration (i.e., SC or IV) should be maintained. Note: The following darbepoetin alfa dosage recommendations are estimates based on total amount of epoetin alfa administered per week. Because of individual variability, titrate doses to maintain the target Hgb.

Estimated Starting Dose (titrate to maintain target Hgb)
Previous weekly dose of epoetin alfa: 1500–2499 units/wk:

  • Darbepoetin dose: 6.25 mcg/wk
Previous weekly dose of epoetin alfa: 2500–4999 units/wk:
  • Darbepoetin dose: 10–12.5 mcg/wk
Previous weekly dose of epoetin alfa: 5000–10,999 units/wk:
  • Darbepoetin dose: 20–25 mcg/wk
Previous weekly dose of epoetin alfa: 11,000–17,999 units/wk:
  • Darbepoetin dose: 40 mcg/wk
Previous weekly dose of epoetin alfa: 18,000–33,999 units/wk:
  • Darbepoetin dose: 60 mcg/wk
Previous weekly dose of epoetin alfa: 34,000–89,999 units/wk:
  • Darbepoetin dose: 100 mcg/wk
Previous weekly dose of epoetin alfa: >90,000 units/wk:
  • Darbepoetin dose: 200 mcg/wk

Administration

All Routes
  • Correct deficiencies of folic acid or vitamin B12 prior to initiation of therapy.
Subcutaneous
  • Do not shake solution. Shaking may denature the darbepoetin, rendering it biologically inactive.
  • Inspect solution for particulate matter prior to use. Do not use if solution is discolored or if it contains particulate matter.
  • Use only one dose per vial, and do not reenter vial.
  • Do not give with any other drug solution.
Intravenous

PREPARE: Direct: Withdraw the desired dose and give undiluted. Discard the unused portion.  

ADMINISTER: Direct: Give direct IV as a bolus dose over 1 min.  

  • Discard any unused portion of the vial. It contains no preservatives.
  • Store at 2°–8° C (36°–46° F). Do not freeze or shake. Protect from light.

Adverse Effects (≥1%)

Body as a Whole: Injection site pain, peripheral edema, fatigue, fever, death, chest pain, fluid overload, access infection, access hemorrhage, flu-like symptoms, asthenia, infection. CNS: Headache, dizziness. CV: Hypertension, hypotension, arrhythmias, cardiac arrest, angina, chest pain, vascular access thrombosis, CHF, red cell aplasia. GI: Nausea, vomiting, diarrhea, constipation. Musculoskeletal: Myalgia, arthralgia, limb pain, back pain. Respiratory: Upper respiratory infection, dyspnea, cough, bronchitis. Skin: Pruritus. Other: Increased risk of thrombotic events and mortality in cancer patients.

Interactions

Drug: No clinically significant reactions reported.

Pharmacokinetics

Absorption: 37% absorbed from SC site. Peak: 24–72 h SC. Distribution: Distribution confined primarily to intravascular space. Elimination: 10% in urine. Half-Life: 21 h IV, 49 h SC.

Nursing Implications

Assessment & Drug Effects

  • Control BP adequately prior to initiation of therapy and closely monitor and control during therapy. Report immediately S&S of CHF, cardiac arrhythmias, or sepsis. Note that hypertension is an adverse effect that must be controlled.
  • Notify physician of a rapid rise in Hgb as dosage will need to be reduced because of risk of serious hypertension. Note that BP may rise during early therapy as Hgb increases.
  • Monitor for premonitory neurological symptoms (i.e., aura, and report their appearance promptly). The potential for seizures exists during periods of rapid Hgb increase (e.g., >1.0 g/dL in any 2-wk period).
  • Monitor closely and report immediately S&S of thrombotic events (e.g., MI, CVA, TIA), especially for patients with CRF.
  • Lab tests: At baseline and periodically thereafter, evaluate iron stores, including transferrin and serum ferritin; Hgb twice weekly until stabilized and maintenance dose is established, then weekly for at least 4 wk, and at regular intervals thereafter; CBC with differential and platelet count at regular interval; periodic BUN, creatinine, serum phosphorus, and serum potassium.

Patient & Family Education

  • Adhere closely to antihypertensive drug regimen and dietary restrictions.
  • Monitor BP as directed by physician.
  • Do not drive or engage in other potentially hazardous activity during the first 90 d of therapy because of possible seizure activity.
  • Report any of the following to the physician: chest pain, difficulty breathing, shortness of breath, severe or persistent headache, fever, muscle aches and pains, or nausea.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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