How should Retacrit (epoetin‑α) be administered and dosed in an adult hemodialysis patient with anemia of chronic kidney disease?

Retacrit Administration in Hemodialysis Patients

For hemodialysis patients, Retacrit (epoetin alfa) should be administered intravenously during the dialysis session, injected into the arterial or venous blood lines of the hemodialysis circuit, at a starting dose of 50-100 units/kg three times weekly (typically 4,000-8,000 units per session for most adults). 1

Route of Administration for HD Patients

Intravenous administration is the standard and recommended route for hemodialysis patients:

• The FDA label specifies that the intravenous route is recommended for patients on hemodialysis 1
• Inject Retacrit directly into the arterial or venous blood lines at any time during the hemodialysis procedure 2
• Critical pitfall: Never inject into the venous drip chamber of the Fresenius delivery system, as this can result in "trapping" and incomplete mixing with the patient's blood 2, 3

Subcutaneous administration is more efficient but less commonly used in HD:

• Subcutaneous dosing requires 15-50% lower doses than IV to maintain the same hemoglobin targets 4, 5, 3
• However, subcutaneous administration carries a theoretical risk of pure red cell aplasia, though this risk has been substantially reduced with improved formulations 4
• If switching from IV to subcutaneous, use two-thirds of the IV weekly dose 5, 3

Dosing Protocol

Initial dosing:

• Start with 50-100 units/kg three times weekly for adults 1
• For a typical 70-kg adult, this translates to 3,500-7,000 units per dialysis session
• The weekly dose should be divided and administered during each dialysis treatment—giving the entire weekly dose once results in a 25% increase in dose requirements and lower hemoglobin response 3

Target hemoglobin:

• Initiate treatment when hemoglobin is less than 10 g/dL 1
• Target hemoglobin of 10-11 g/dL; do not exceed 11 g/dL 1
• Higher targets (>11 g/dL) are associated with increased mortality and cardiovascular events 5, 1

Monitoring Requirements

Frequency of monitoring:

• Measure hemoglobin weekly after initiation or dose adjustment until stable 1
• Once stable, monitor at least monthly 1
• With optimal iron stores, expect hemoglobin to rise approximately 0.3 g/dL per week 2, 5

Iron status must be evaluated and maintained:

• Check serum ferritin and transferrin saturation before and during treatment 1
• Maintain transferrin saturation >20% and ferritin >100 mcg/L 2
• Iron deficiency is the most common cause of inadequate response to epoetin 2, 3
• The majority of HD patients will require supplemental IV iron during ESA therapy 1

Dose Adjustments

If hemoglobin rises too rapidly (>1 g/dL in any 2-week period):

• Reduce dose by 25% 1
• This prevents hypertension and seizures associated with rapid hemoglobin increases 4

If hemoglobin approaches or exceeds 11 g/dL:

• Reduce or interrupt the dose 1
• Resume at 25% lower dose when hemoglobin declines 1

If inadequate response (hemoglobin increase <1 g/dL after 4 weeks):

• Increase dose by 25% 1
• If no response after 12 weeks of dose escalation, further increases are unlikely to help and may increase risks 1
• Evaluate for other causes of anemia (bleeding, infection, inflammation, vitamin deficiency) 1

Dosing Frequency Considerations

Three times weekly is required for IV administration:

• Intravenous epoetin has a half-life of only 5-11 hours, necessitating three-times-weekly dosing 4
• Reducing frequency to once or twice weekly with IV administration leads to increased dose requirements 4, 3
• This differs from subcutaneous administration, where the half-life is 19-25 hours and less frequent dosing may be feasible 4

Practical Implementation

Administration technique:

• Draw up the prescribed dose from the vial
• Inject into the arterial or venous blood line during any point in the dialysis session 2
• Rotate injection sites if using subcutaneous route (upper arm, thigh, abdomen) 3
• Use single-dose vials for pregnant women, lactating women, neonates, and infants (benzyl alcohol-free formulation) 1

Common causes of treatment failure:

• Iron deficiency (most common—check iron studies) 2, 3
• Infection or inflammation (reduces erythropoietic response) 2, 3
• Blood loss (occult or overt) 1
• Inadequate dialysis 4
• Hyperparathyroidism 4