Pharmacodynamics: Following intravenous administration of Venofer®, iron sucrose is dissociated by the reticuloendothelial system into iron and sucrose. In 22 hemodialysis patients on erythropoietin (recombinant human erythropoietin) therapy treated with iron sucrose containing 100 mg of iron, three times weekly for three weeks, significant increases in serum iron and serum ferritin and significant decreases in total iron binding capacity occurred four weeks from the initiation of iron sucrose treatment.
Pharmacokinetics: In healthy adults treated with intravenous doses of Venofer®, its iron component exhibits first order kinetics with an elimination half-life of 6 h, total clearance of 1.2 L/h, non-steady state apparent volume of distribution of 10.0 L and steady state apparent volume of distribution of 7.9 L. Since iron disappearance from serum depends on the need for iron in the iron stores and iron utilizing tissues of the body, serum clearance of iron is expected to be more rapid in iron deficient patients treated with Venofer® as compared to healthy individuals. The effects of age and gender on the pharmacokinetics of Venofer® have not been studied.
Venofer® is not dialyzable through CA210 (Baxter) High Efficiency or Fresenius F80A High Flux dialysis membranes. In in vitro studies, the amount of iron sucrose in the dialysate fluid was below the levels of detection of the assay (less than 2 parts per million).
Distribution: In healthy adults receiving intravenous doses of Venofer®, its iron component appears to distribute mainly in blood and to some extent in extravascular fluid. A study evaluating Venofer® containing 100 mg of iron labeled with 52Fe/59Fe in patients with iron deficiency shows that a significant amount of the administered iron distributes in the liver, spleen and bone marrow and that the bone marrow is an iron trapping compartment and not a reversible volume of distribution.
Metabolism and Elimination: Following intravenous administration of Venofer®, iron sucrose is dissociated into iron and sucrose by the reticuloendothelial system. The sucrose component is eliminated mainly by urinary excretion. In a study evaluating a single intravenous dose of Venofer® containing 1,510 mg of sucrose and 100 mg of iron in 12 healthy adults (9 female, 3 male: age range 32-52), 68.3% of the sucrose was eliminated in urine in 4 h and 75.4% in 24 h. Some iron also is eliminated in the urine. Neither transferrin nor transferrin receptor levels changed immediately after the dose administration . In this study and another study evaluating a single intravenous dose of iron sucrose containing 500-700 mg of iron in 26 anemic patients on erythropoietin therapy (23 female, 3 male; age range 16-60), approximately 5% of the iron was eliminated in urine in 24 h at each dose level .
Drug-drug Interactions: Drug-drug interactions involving Venofer® have not been studied. However, like other parenteral iron preparations, Venofer® may be expected to reduce the absorption of concomitantly administered oral iron preparations.
Venofer® is used to replenish body iron stores in non-dialysis dependent-chronic kidney disease (NDD-CKD) patients receiving erythropoietin and in NDD-CKD patients not receiving erythropoietin, and in hemodialysis dependent-chronic kidney disease (HDD-CKD) and peritoneal dialysis dependent-chronic kidney disease (PDD-CKD) patients receiving erythropoietin. Iron deficiency may be caused by blood loss during dialysis, increased erythropoiesis secondary to erythropoietin use, and insufficient absorption of iron from the gastrointestinal tract. Iron is essential to the synthesis of hemoglobin to maintain oxygen transport and to the function and formation of other physiologically important heme and non-heme compounds. Most dialysis patients require intravenous iron to maintain sufficient iron stores.
Six clinical trials were conducted to assess the safety and efficacy of Venofer®. Five studies were conducted in the United States (516 patients) and one was conducted in South Africa (131 patients).
Study A: Hemodialysis Dependent-Chronic Kidney Disease (HDD–CKD)
Study A was a multicenter, open-label, historically-controlled study in 101 hemodialysis patients (77 patients with Venofer® treatment and 24 in the historical control group) with iron deficiency anemia. Eligibility for Venofer® treatment included patients undergoing chronic hemodialysis three times weekly, receiving erythropoietin, hemoglobin concentration greater than 8.0 and less than 11.0 g/dL for at least two consecutive weeks, transferrin saturation < 20%, and serum ferritin < 300 ng/mL. The mean age of the patients in the treatment group was 65 years with the age range being 31 to 85 years of age. The erythropoietin dose was to be held constant throughout the study. The protocol did not require administration of a test dose; however, some patients received a test dose at the physician's discretion. Exclusion criteria included significant underlying disease, asthma, active inflammatory disease, or serious bacterial or viral infection. Venofer® 5 mL containing 100 mg of elemental iron was administered through the dialysis line at each dialysis session either as slow injection or a saline diluted slow infusion for a total of 10 dialysis sessions with a cumulative dose of 1,000 mg elemental iron. A maximum of 15 mLs (300 mg of elemental iron) of Venofer® was administered per week.
No additional iron preparations were allowed until after the Day 57 evaluation. The mean change in hemoglobin from baseline to Day 24 (end of treatment), Day 36, and Day 57 was assessed. The historical control population consisted of 24 patients with similar ferritin levels as patients treated with Venofer®, who were off intravenous iron for at least 2 weeks and who had received erythropoietin therapy with hematocrit averaging 31-36 for at least two months prior to study entry. The mean age of patients in the historical control group was 56 years, with an age range of 29 to 80 years. Patient age and serum ferritin level were similar between treatment and historical control patients. Of the 77 patients in the treatment group, 44 (57%) were male and 33 (43%) were female. The mean baseline hemoglobin and hematocrit, were higher and erythropoietin dose was lower in the historical control population than the Venofer® treated population.
Patients in the Venofer® treated population showed a statistically significantly greater increase in hemoglobin and hematocrit than did patients in the historical control population. See Table 1.
Table 1. Changes from Baseline in Hemoglobin and Hematocrit
|Efficacy parameters||End of treatment||2 week follow-up||5 week follow-up|
**p<0.01 and *p<0.05 compared to historical control from ANCOVA analysis with baseline hemoglobin, serum ferritin and erythropoietin dose as covariates.
Serum ferritin increased significantly (p=0.0001) at endpoint of study from baseline in the Venofer®-treated population (165.3±24.2 ng/mL) compared to the historical control population (-27.6±9.5 ng/mL). Transferrin saturation also increased significantly (p=0.0016) at endpoint of study from baseline in the Venofer®-treated population (8.8±1.6%) compared to this historical control population (-5.1±4.3%) .
Study B: Hemodialysis Dependent-Chronic Kidney Disease (HDD-CKD)
Study B was a multicenter, open label study of Venofer® (iron sucrose injection, USP) in 23 iron deficient hemodialysis patients who had been discontinued from iron dextran due to intolerance. Eligibility criteria and Venofer® administration were otherwise identical to Study A. The mean age of the patients in this study was 53 years, with ages ranging from 21-79 years. Of the 23 patients enrolled in the study, 10 (44%) were male and 13 (56%) were female. The ethnicity breakdown of patients enrolled in this study was as follows: Caucasian (35%); Black (35%); Hispanic (26%); Asian (4%). The mean change from baseline to the end of treatment (Day 24) in hemoglobin, hematocrit, and serum iron parameters was assessed.
All 23 enrolled patients were evaluated for efficacy. Statistically significant increases in mean hemoglobin (1.1±0.2 g/dL), hematocrit (3.6±0.6%), serum ferritin (266.3±30.3 ng/mL) and transferrin saturation (8.7±2.0%) were observed from baseline to end of treatment .
Study C: Hemodialysis Dependent-Chronic Kidney Disease (HDD-CKD)
Study C was a multicenter, open-label, two period (treatment followed by observation period) study in iron deficient hemodialysis patients. Eligibility for this study included chronic hemodialysis patients with a hemoglobin less than or equal to 10 g/dL, a serum transferrin saturation less than or equal to 20%, and a serum ferritin less than or equal to 200 ng/mL, who were undergoing maintenance hemodialysis 2 to 3 times weekly. The mean age of the patients enrolled in this study was 41 years, with ages ranging from 16-70 years. Of 130 patients evaluated for efficacy in this study, 68 (52%) were male and 62 (48%) were female. The ethnicity breakdown of patients enrolled in this study was as follows: Caucasian (23%); Black (23%); Asian (5%); Other (mixed ethnicity) (49%). Forty-eight percent of the patients had previously been treated with oral iron. Exclusion criteria were similar to those in studies A and B. Venofer® was administered in doses of 100 mg during sequential dialysis sessions until a pre-determined (calculated) total dose of iron was administered.
Patients received Venofer® at each dialysis session, two to three times weekly. One hour after the start of each session, 5 mL iron sucrose (100 mg iron) in 100 mL 0.9% NaCl was administered into the hemodialysis line. A 50 mg dose (2.5 mL) was given to patients within two weeks of study entry. Patients were treated until they reached an individually calculated total iron dose based on baseline hemoglobin level and body weight. Twenty-seven patients (20%) were receiving erythropoietin treatment at study entry and they continued to receive the same erythropoietin dose for the duration of the study.
Changes from baseline to observation week 2 and observation week 4 (end of study) were analyzed.
The modified intention-to-treat population consisted of 131 patients. Significant (p<0.0001) increases from baseline in mean hemoglobin (1.7 g/dL), hematocrit (5%), serum ferritin (434.6 ng/mL), and serum transferrin saturation (14%) were observed at week 2 of the observation period and these values remained significantly increased (p<0.0001) at week 4 of the observation period.
Study D: Non-Dialysis Dependent-Chronic Kidney Disease (NDD-CKD)
Study D was a randomized, open-label, multicenter, active–controlled study of the safety and efficacy of oral iron versus intravenous iron sucrose (Venofer®) in NDD-CKD patients with or without erythropoietin therapy. Erythropoietin therapy was stable for 8 weeks prior to randomization. In the study 188 patients with NDD-CKD, transferrin saturation ≤ 25%, ferritin ≤ 300 ng/mL and an average baseline hemoglobin of ≤ 11.0 g/dL were randomized to receive oral iron (325 mg ferrous sulfate three times daily for 56 days); or Venofer® (either 200 mg over 2-5 minutes 5 times within 14 days or two 500 mg infusions on Day 1 and Day 14, administered over 3.5-4 hours). Of the 188 randomized patients, 182 were treated and followed for up to 56 days. Efficacy assessments were measured on days 14, 28, 42 and 56. The mean age of the 91 treated patients in the Venofer® group was 61.6 years (range 25 to 86 years) and 64 years (range 21 to 86 years) for the 91 patients in the oral iron group. Ethnicity breakdown of the patients in the Venofer® group was as follows: Caucasian (60.4%), Black (34.1%), Hispanic (3.3%), Other (2.2%). Ethnicity breakdown for the oral iron group was: Caucasian (50.5%), Black (44.0%), Hispanic (4.4%), Other (1.1%). Patient demographic characteristics were not significantly different between the groups. A statistically significantly greater proportion of Venofer® subjects (35/79; 44.3%) compared to oral iron subjects (23/82; 28%) had an increase in hemoglobin≥1 g/dL at anytime during the study (p= 0.03). In patients ≥ 65 years of age, the proportion of subjects achieving ≥ 1.0 g/dL increase in hemoglobin from baseline was 53% (20/38) in the Venofer® group compared to 23% (10/43) in the oral iron group. In patients <65 years of age, the proportion of subjects achieving ≥ 1.0 g/dL increase in hemoglobin from baseline was 37% (15/41) in the Venofer® group compared to 33% (13/39) in the oral iron group. A statistically significantly greater proportion of Venofer® treated patients (31/79; 39.2%) compared to oral iron treated patients (1/82; 1.2%) had an increase in hemoglobin ≥1 g/dL and ferritin ≥160 ng/mL at anytime during the study (p<0.0001).
Study E: Peritoneal Dialysis Dependent-Chronic Kidney Disease (PDD-CKD)
Study E was a randomized [2:1 treatment: control], open-label, multicenter study comparing PDD-CKD patients receiving an erythropoietin and IV iron to PDD-CKD patients receiving an erythropoietin alone without iron supplementation. 126 patients with PDD-CKD, stable erythropoietin for 8 weeks, TSAT≤25%, Ferritin ≤500 ng/mL and an average baseline hemoglobin of ≤11.5 g/dL were randomized to receive either no iron or Venofer® (iron sucrose injection, USP) (300 mg in 250 mL 0.9% NaCl over 1.5 hours on Day 1 and 15 and 400 mg in 250 mL 0.9% NaCl over 2.5 hours on Day 29). 121 of the 126 randomized patients were treated and followed for up to 71 days with a total of 88 patients who completed the study. Efficacy assessments were measured on days 15, 29, 43, 57 and 71. Patient demographic characteristics were not significantly different between the groups. The mean age of the 75 treated patients in the Venofer® / erythropoietin group was 51.9 years (range 21 to 81 years) vs. 52.8 years (range 23 to 77 years) for 46 patients in the erythropoietin alone group. Ethnicity breakdown of the patients in the Venofer® / erythropoietin group was as follows: Caucasian (36%); Hispanic (32 %); Black (21.3%); Other (10.7%). Ethnicity breakdown for the erythropoietin alone group was: Hispanic (43.5%); Caucasian (30.4%); Black (15.2%); Other (10.9%). Patients in the Venofer® / erythropoietin group had statistically significantly greater mean change from baseline to the highest hemoglobin value (1.3 g/dL), compared to subjects who received erythropoietin alone (0.6 g/dL) (p<0.01). A statistically significantly greater proportion of subjects treated with Venofer® / erythropoietin (59.1 %) had an increase in hemoglobin of ≥1 g/dL at any time during the study compared to the subjects who received erythropoietin only (33.3%) (p < 0.05).