The purpose of this research study was to determine if the activity of erythropoietin (r-HuEPO) is time dependent when given to chronic renal failure patients at three different times of day.

This phase-II crossover study was designed to test if the activity of erythropoietin is time dependent. Patients with chronic renal failure on hemodialysis requiring r-HuEPO to maintain adequate levels of hematocrit are eligible for the study. Patients were administered r-HuEPO subcutaneously three times per week, 50 U/kg, rounded to the nearest 2000 units. r-HuEPO will be administered until the hematocrit rises from the baseline level of 20-24% to the target level of 30-34%. This will be repeated three times, each at different times of day, either 0800, 1500 or 2200 hrs and the order of these will be randomly determined. Each patient will complete all three of the phases.

Inclusion Criteria:

• Chronic renal failure patients requiring hemodialysis and requiring r-HuEPO to maintain adequate hematocrit levels
• Serum ferritin level > 200 micrograms/L and transferrin saturation > 15%
• Serum erythropoietin level less than 500 mu/ml (when off r-HuEPO)
• Prior therapy with r-HuEPO
• An adequate program of dialysis established
• Informed consent signed

Exclusion Criteria:

• Adocumented cause of anemia other than chronic renal disease
• Symptoms of unstable coronary artery disease
• Poorly controled hypertension
• Known seizure disorder
• Other active inflammatory or infective disorders
• Other disorders that may diminish the response of the bone marrow to r-HuEPO