Darbepoetin alfa

darbepoetin alfa

(dar bah poe e' tin)

Aranesp

Pregnancy Category C

Drug class

Erythropoiesis-stimulating protein

Therapeutic actions

An erythropoetin-like glycoprotein hormone produced by recombinant DNA technology; stimulates red blood cell production in the bone marrow in the same manner as naturally occurring erythropoetin, a hormone released into the bloodstream in response to renal hypoxia.

Indications

·        Treatment of anemia associated with chronic renal failure, including during dialysis

·        Treatment of chemotherapy-induced anemia in patients with nonmyeloid malignancies

Contraindications and cautions

·        Contraindicated with uncontrolled hypertension or hypersensitivity to any component of the drug.

·        Use cautiously with hypertension, pregnancy, lactation.

Available forms

Polysorbate solution for injection—25, 40, 60, 100, 150, 200, 300, 500 mcg/mL

Dosages

ADULTS

·        Starting dose: 0.45 mcg/kg IV or subcutaneously once per wk. Dosage may be adjusted no more frequently than once per mo. Target Hgb level is 12 g/dL. Adjust dosage by 25% at a time to achieve that level. Avoid rapid increase in Hgb.

·        Switching from epoetin alfa:

Epoetin alfa dose in units/wk	Darbepoetin alfa dose in mcg/wk
< 2,500	6.25
2,500–4,999	12.5
5,000–10,999	25
11,000–17,999	40
18,000–33,999	60
34,000–89,999	100
³ 90,000	200

Patients who were receiving epoetin two to three times per week should receive darbepoetin once per wk. Patients who were receiving epoetin once per wk should receive darbepoetin once every 2 wk.

·        Chemotherapy-induced anemia: 2.25 mg/kg subcutaneously once per wk; adjust to maintain acceptable Hgb levels.

PEDIATRIC PATIENTS

Safety and efficacy not established.

PATIENTS WITH CHRONIC RENAL FAILURE

IV administration should be used instead of subcutaneous injection. Dosage should start slowly and be increased based on Hgb levels; check Hgb levels weekly until stable, then monthly.

Pharmacokinetics

Route	Peak	Duration
SC	34 hr	24–72 hr
IV	1.4 hr	24–72 hr

Metabolism: Serum; T_1/2: 21 hr (IV), 49 hr (subcutaneous)

Distribution: Crosses placenta; enters breast milk

Excretion: Urine

IV facts

Preparation: Administer as provided, no additional preparation needed. Enter vial only once, discard any unused solution. Refrigerate. Do not shake vial. Inspect for any discoloring or precipitates before use.

Infusion: Administer by direct IV injection or into tubing of running IV.

Incompatibilities: Do not mix with any other drug solution.

Adverse effects

·        CNS: Headache, fatigue, asthenia, dizziness, seizure, TIA

·        CV: Hypertension, edema, chest pain, arrhythmias, chest pain, MI, stroke, CVA

·        GI: Nausea, vomiting, diarrha, abdominal pain

·        Respiratory: URI, dyspnea, cough

·        Other: Arthralgias, myalgias, limb pain, clotting of access line, pain at injection site, development of anti-erythropoetin antibodies with subsequent pure red cell aplasia and extreme anemia

Nursing considerations

Assessment

·        History: Hypertension; hypersensitivity to any component of product, pregnancy, lactation

·        Physical: Reflexes, affect, BP, P, R, adventitious sounds, urinary output, renal function, renal function tests, CBC, Hct, iron levels, electrolytes

Interventions

·        WARNING: Ensure chronic, renal nature of anemia. Darbepoetin is not intended as a treatment of severe anemia and is not a substitute for emergency transfusion.

·        Prepare solution by gently mixing. Do not shake; shaking may denature the glycoprotein. Use only one dose per vial; do not reenter the vial. Discard unused portions.

·        Do not administer with any other drug solution.

·        Administer dose once weekly. If administered independent of dialysis, administer into venous access line. If patient is not on dialysis, administer IV or subcutaneously.

·        Monitor access lines for signs of clotting.

·        Arrange for Hct reading before administration of each dose to determine appropriate dosage. If patient fails to respond within 4 wk of therapy, evaluate patient for other causes of the problem.

·        Evaluate iron stores before and periodically during therapy. Supplemental iron may be needed.

·        Monitor diet and assess nutrition; arrange for nutritional consult as necessary.

·        Establish safety precautions (eg siderails, environmental control, lighting) if CNS effects occur.

·        Maintain seizure precautions during administration.

·        Provide additional comfort measures, as necessary, to alleviate discomfort from GI effects, headache.

·        Offer support and encouragement to deal with chronic disease and need for prolonged therapy and testing.

Teaching points

·        The drug will need to be given once a week and can only be given IV or subcutaneously or into a dialysis access line. Prepare a schedule of administration dates.

·        Keep appointments for blood tests; frequent blood tests will be needed to determine the effects of the drug on your blood count and to determine the appropriate dosage needed.

·        Maintain all of the usual activities and restrictions that apply to your chronic renal failure. If this becomes difficult, consult with your health care provider.

·        You may experience these side effects: Dizziness, headache (avoid driving a car or performing hazardous tasks); headache, fatigue, joint pain (consult with your health care provider if these become bothersome; medications may be available to help); nausea, vomiting, diarrhea (proper nutrition is important; consult with your dietitian to maintain nutrition and ensure ready access to bathroom facilities); upper respiratory tract infection, cough (consult with your health care provider if this occurs).

·        Report difficulty breathing, numbness or tingling, chest pain, seizures, severe headache.

Adverse effects in Italic are most common; those in Bold are life-threatening.