Subcutaneous administration of recombinant human erythropoietin to subjects on continuous ambulatory peritoneal dialysis: an erythrokinetic assessment

Erythropoietin Administration for Anemia Due to Chronic Kidney Disease - Subcutaneous OR Intravenous, What Do We Know So Far?

The prevalence of anemia in chronic kidney disease (CKD) patients is almost twice that of the normal population and its severity increases exponentially as the disease worsens, dramatically affecting the quality of an individual’s life. The advent of erythropoiesis stimulating agents (ESA) in the 1980s saw a revolutionary change in the treatment of anemia in CKD patients, drastically improving quality of life (QoL), overall health and reducing the need for blood transfusions. Numerous ESAs have been developed ever since and are in current use, with the primary routes of administration being intravenous (IV) and subcutaneous (SC) injections. Their use, however, has stirred significant controversy over the last two decades. Additionally, despite numerous studies and trials, the latest international recommendations for their use do not provide clear cut guidance with well-grounded evidence on the recommended route of administration for different sets of patients. Instead, this decision has mainly been left up to the physician’s discretion, whilst keeping certain key factors in mind. This review shall summarize, discuss and compare the findings of previous studies on various factors governing the two aforementioned routes of administration and identify areas that need further exploration.

Effect of Erythropoietin in Continuous Ambulatory Peritoneal Dialysis Patients: Comparison between Intravenous and Intraperitoneal Administration

The administration of recombinant human erythropoietin (rHuEPO) in CAPD patients is usually done subcutaneously. Only a few authors have reported on its intraperitoneal (IP) administration. We compared the effect of IP administration of rHuEPO in CAPD patients to that of intravenous (IV) administration. Ten anemic CAPD patients injected rHuEPO into their dialysis bag once a day, 3 times a week, for 18 weeks. The initial dose was 12000 U. The dwell time of the exchanges with rHuEPO was about 6 hours. Nineotheranemic CAPD patients were treated with IV rHuEPO once a week for 18 weeks. The initial dose was 6000 U. In the IP group the hematocrit rose from 24.04±2.7% to 33.3±3.8% (mean±SD). In the IV group 2 patients were excluded from the efficiency evaluation. In 7 of the 9 patients in the IV group, the hematocrit rose from 23.27±2.6% to 32±5.5% (mean±SD).

The intraperitoneal administration of rHuEPO in CAPD patients is sufficient in improving anemia, although it requires a much larger dosage to yield the same level of improvement as the one obtained with the intravenous administration. However, in patients on continuous cycling peritoneal dialysis or IP dialysis, a smaller dosage during the prolonged dwell time may be effective.

Endocrinology and Pd: Optimal Treatment of Anemia in Peritoneal Dialysis Patients

The optimal treatment of anemia in peritoneal dialysis is given by subcutaneous administration of epoetin. The optimal dosing frequency is in most patients 2 -3 injections per week, but in responsive patients once a week may be enough during the maintenance phase. Both before starting and during epoetin treatment it is necessary to monitor for factors causing hyporesponsiveness. The epoetin dose is adjusted monthly aiming at an increase in Hb concentration of 10 g/L per month. Further studies are required to define the optimal target Hb concentration. Iron supplements should be administered routinely. Parenteral iron may be used liberally when oral supplements are ineffective or inconvenient.

In the initial three-month period of peritoneal dialysis a marked increase in Hb concentration is common, and if epoetin treatment is necessary low starting doses will be sufficient. In patients with moderate anemia, adequate iron stores and iron availability, and no significant comorbidity, low starting doses are recommended (50 75 U kg-1 week-1). Patients with severe anemia or with comorbidity usually require higher doses and may be started with 75 150 kg-1 week-1. Hypertension is the principal adverse effect of epoetin treatment in patients with chronic renal failure, but it is usually easily controlled by fluid control and/or increased antihypertensive medication.

Subcutaneous Epoetin Beta in Renal Anemia: An Open Multicenter Dose Titration Study of Patients on Continuous Peritoneal Dialysis

Objective

To establish dose requirements (target hemoglobin >100 g/L) and safety of subcutaneously administered epoetin beta.

Design

Open multicenter study.

Patients

Forty-five anemic patients (21 female, 24 male; mean age 55 years; range 20 79 years) who had been on continuous peritoneal dialysis for 1-157 months (mean 24 months). Thirty patients required blood transfusions during the year prior to the study. Mean hemoglobin concentration pretreatment was 75 g/L (range 57 –89 g/L).

Intervention

After a pretreatment period of two weeks, 60 IU kg-1 week-1 divided into three weekly doses of epoetin beta was administered subcutaneously. The dose was increased by 60 IU kg-1 week-1 after ten weeks, and when necessary, every fourth week in patients with hemoglobin levels below 100 g/L.

Main Outcome Measures

Hemoglobin concentration. Analysis of factors affecting the response to epoetin beta. Safety of epoetin beta.

Results

Thirty-eight of the 45 patients completed six months and 21 patients completed one year in the study. Twenty-six patients reached hemoglobin 100 g/L within six months and 8 patients did later on. The mean hemoglobin concentration after three months was 93 g/L (range 64 –144 g/L) and after six months was 99 g/L (range 59 –130 g/L; mean epoetin beta dose 1221U kg-1 week-I). During the second six-month period of the study, hemoglobin levels were stable in most patients. After one year, the mean hemoglobin was 110 g/L (range 84 –153 g/L) and the mean epoetin beta dose was 1071U kg-1 week-l. Prolonged correction time and impaired response to epoetin were observed in patients with infections or hemorrhages and in patients with low hemoglobin concentration before starting epoetin treatment. Iron deficiency was controlled by iron supplementation, either orally or, in 10 patients, intravenously. Increased blood pressure, requiring intensified antihypertensive treatment, was observed in 13 patients.

Conclusions

Continuous peritoneal dialysis patients with moderate anemia (Hb 75 –90 g/L) and without complicating disorders can be managed with subcutane0usdoses of ep0etin<1201U kg-lweek-l. Theepoetin beta dose should be adjusted after the first month of treatment since most patients required higher doses than the initial 60 IU kg-1 week-l.

Pathogenesis of anaemia in hyperparathyroidism

It is suggested that parathyroid hormone (PTH), when in excessive amounts, interferes with normal erythropoiesis by downregulating the erythropoietin receptors on erythroid progenitor cells in the bone marrow. Therefore, physiologic concentrations of EPO can no longer sustain normal red cell counts, so normocytic and normochromic anaemia ensues. In primary hyperparathyroidism (HPT), this effect is observed with very high concentrations of PTH. In secondary HPT during chronic renal failure, this effect is more pronounced because erythropoietin synthesis is impaired.

The Effect of Recombinant Human Erythropoietin on Platelet Counts Is Strongly Modulated by the Adequacy of Iron Supply

The effect of recombinant human erythropoietin (rHuEpo) on megakaryopoiesis remains controversial. Treatment with rHuEpo in renal failure patients has been associated with a slight elevation of platelet counts. In animal studies, high doses of rHuEpo produced an increase of platelet counts followed by a gradual return to normal after 7 to 15 days or even a substantial degree of thrombocytopenia. However, because iron deficiency is also known to be associated with thrombocytosis, (functional) iron deficiency during rHuEpo could be contributing to these observations. We investigated the impact of iron supply on changes in platelet counts induced by rHuEpo. Rats were either fed normal food (normal rats) or received 1% carbonyl iron for 2 weeks or 3 months, as well as during the experiment, to achieve iron supplementation or overload, respectively. Rats of all three categories then received daily intravenous injections of rHuEpo (10, 50, or 150 U) or normal saline (0 U) for 20 days. With 0 to 10 U rHuEpo, platelets remained stable. In normal rats receiving 50 to 150 U rHuEpo, platelets increased to 120% to 140% of baseline at 4 to 12 days to level off at 120% at 16 to 20 days. This response was less sustained in splenectomized animals. Iron-supplemented rats receiving 50 to 150 U rHuEpo also increased platelets initially, but the peak was at day 4, followed by a gradual return to baseline and even a moderate thrombocytopenia later on. Iron-overloaded rats receiving 50 to 150 U rHuEpo also had increased platelets at day 4, but the duration of platelet increase was shorter, and they experienced a more pronounced degree of thrombocytopenia in proportion to the dose of rHuEpo. Because the early elevation of platelets was of larger magnitude than hematocrit changes, it is unlikely that it could be accounted for by shrinkage of plasma volume. Because it was observed in all three iron conditions, there appears to be some direct positive effect of rHuEpo on platelet production. However, after this transient effect, expanded erythropoiesis appears to exert a negative impact upon platelet production. Secondary thrombocytopenia was not related to splenic pooling, and its very slow correction after cessation of rHuEpo therapy is not compatible with changes in platelet survival. Rather, it is consistent with stem cell competition between erythroid and megakaryocytic development. However, this secondary thrombocytopenia is masked by (functional) iron deficiency in rats not receiving an adequate iron supply from food or stores.

Increased susceptibility to erythrocyte C5b-9 deposition and complement-mediated lysis in chronic renal failure

BACKGROUND

Decreased red blood cell survival contributes to the anemia of chronic renal failure patients. Because patients on chronic dialysis therapy are frequently exposed to excessive complement activation, we investigated the susceptibility of this patient population to erythrocyte C5b-9 deposition, complement-mediated lysis, and ghost formation.

METHODS

We developed a flow cytometric assay using antibodies to both glycophorin and the C5b-9 complex to detect C5b-9 deposition on intact erythrocytes and erythrocyte ghosts. Serum C5b-9 levels and C5b-9 deposition on erythrocyte ghosts were measured by enzyme-linked immunosorbent assay.

RESULTS

A significant increase in C5b-9 deposition on intact erythrocytes was demonstrated in patients with advanced chronic renal failure (2.2 +/- 0.5%) and in patients on chronic maintenance hemodialysis (2.3 +/- 0.4%) compared with normal volunteers (0.9 +/- 0.1%, P = 0.005 vs. chronic renal failure, P < 0.001 vs. chronic hemodialysis patients). There was also a significantly higher percentage of C5b-9-positive erythrocyte ghosts in patients with advanced chronic renal failure (20.6 +/- 5%) and in chronic hemodialysis patients (15.5 +/- 3.1%) compared with normal controls (2.6 +/- 0.9%, P < or = 0.001 vs. advanced chronic renal failure and chronic hemodialysis patients). Treatment of erythrocyte preparations with cobra venom factor, which activates the complement cascade, resulted in dramatic increases in the percentages of C5b-9-positive erythrocyte ghosts in patients with chronic renal failure (49.9 +/- 6.9%) and in chronic hemodialysis patients (45.0 +/- 4.2%) compared with normal volunteers (22.3 +/- 2.7%, P < 0.001 vs. chronic renal failure and chronic hemodialysis patients). Erythrocyte membrane expression of the complement regulatory proteins CD59 and CD55 did not significantly differ between normal controls and hemodialysis patients. Plasma C5b-9 levels after cobra venom factor stimulation were higher in chronic renal failure patients (538 micrograms/ml) compared with normal controls (345 micrograms/ml, P < 0.001).

CONCLUSIONS

Patients with chronic renal failure and on hemodialysis therapy are susceptible to erythrocyte C5b-9 deposition with subsequent lysis and ghost formation. Susceptibility to complement-mediated erythrocyte injury may contribute to the anemia of chronic renal disease.

Better response to s.c. erythropoietin in CAPD than HD patients

The clinical efficacy of s.c. erythropoietin (EPO) injected subcutaneously once weekly was compared in patients (median age of 63 years) on peritoneal dialysis (PD, n = 19) and in haemodialysis (HD, n = 13). The blood haemoglobin prior to start of EPO was not significantly different between the groups. The mean (+/- SD) dose of EPO given to achieve a blood haemoglobin level of 100 g/l was not significantly different between the PD and the HD-responders (85 +/- 45 units/kg body weight and week, versus 112 +/- 33, respectively). Significantly more patients using PD than in HD achieved a haemoglobin level > or = 95 g/l (p = 0.02). The HD group had significantly higher ferritin values. Serum iron and intact PTH were not different between the groups. In conclusion, s.c. EPO injections once, or occasionally twice, weekly increased blood haemoglobin levels in a greater proportion of patients on PD than in those on HD.

Cisplatin-associated anemia: an erythropoietin deficiency syndrome

Cisplatin-based therapy results in a cumulative anemia that is disproportionate to the effects on other blood cells. The severity of this treatment-induced anemia and the resultant transfusion requirement in cancer patients correlate with cisplatin-induced renal tubular dysfunction. Observed/expected serum erythropoietin (EPO) ratios decline with progressive cisplatin therapy and are proportionate to the degree of renal dysfunction. Recovery from anemia and of observed/expected serum EPO ratios in patients occurs after cessation of cisplatin therapy, along with restoration of renal tubular function. Creatinine clearance, however, remains permanently depressed. Cisplatin-treated rats develop progressive renal dysfunction and anemia that persists for many weeks, without effects on white blood cell counts. The anemia is also associated with a lack of expected EPO and reticulocyte response. With EPO administration, cisplatin-treated rats exhibit a greater reticulocyte response and hematocrit increment then non-cisplatin-treated rats given EPO, indicating minimal erythroid precursor cell damage from cisplatin. These results indicate the primary etiology of cisplatin-associated anemia is a transient, but persisting EPO deficiency state resulting from cisplatin-induced renal tubular damage, which can be prevented or treated by hormone (EPO) replacement.

Effect of recombinant human erythropoietin on platelets in patients with anemia of renal failure: correlation of platelet count with erythropoietic activity and iron parameters

We examined the effect of treatment with rHuEpo on platelet counts in 61 hemodialysis patients and correlated them with changes in erythropoietic activity, iron status and inflammation. Platelets (10(9)/1) increased from 220 +/- 80 to 245 +/- 102 after 14 days and stabilized at that level up to day 90 (p < 0.0001). The increment was similar in complete or partial responders but was not observed in failures. Serum transferrin receptor (sTfR, a measure of total erythropoiesis) and Het rose much more progressively, but relative platelet increments correlated with relative increases in sTfR and Hct. Relative platelet increments correlated inversely with relative changes of SeFe or transferrin saturation, but not with their absolute values, nor with baseline ferritin or its progressive decrease. Although baseline platelet count was 12% higher in patients with inflammation and correlated with serum haptoglobin, relative increases were similar in patients with or without inflammation. In conclusion, rHuEpo produced a clinically minor but consistent elevation of platelet counts. These modifications were not related primarily to modifications in iron stores, functional iron deficiency, or inflammation, but paralleled the expansion of erythropoietic activity. The results suggest that rHuEpo has a small positive effect on platelet production, but it cannot be ruled out that this could be partially mediated through functional iron deficiency.

Medicare payment policy and recombinant erythropoietin prescribing for dialysis patients

The Medicare payment policy for recombinant human erythropoietin (rHuEPO) treatment for dialysis patients changed in January 1991 from a relatively fixed payment per treatment (allowed charge of $40 per < or = 10,000 units injected) to a more variable payment based on the amount of rHuEPO administered with each treatment (allowed charge of $11 per 1,000 units injected). This change provided an opportunity to examine how payment policy can effect the use, cost, and health outcome of a biotechnology product used in the dialysis population. In cross-sectional (n = 71,880 Medicare-entitled dialysis patients) and longitudinal (n = 29,088 Medicare-entitled dialysis patients) study designs, we used Medicare end-stage renal disease program and claims data in bivariate and multivariate analyses to examine the effect of the change in payment policy for rHuEPO on access to the biotechnology, dosing, costs, and hematocrit, including the prescribing patterns at for-profit versus not-for-profit providers. The observation period included several months before (July 1989 to December 1990) and 6 months after (January to June 1991) the change in Medicare payment policy. The mean dose per treatment during the initial and fourth month of therapy was low (2,742 [95% confidence interval, 2,703 to 2,781] units and 2,632 [95% confidence interval, 2,598 to 2,667] units, respectively, in June 1990) and increased 3.4% and 5.0%, respectively, in the next 6 months prior to the change in Medicare payment policy compared with 14.6% and 14.8%, respectively, in the 6 months following the change in payment policy. The average monthly allowed charge for rHuEPO per dialysis patient receiving rHuEPO decreased from $455 before the policy change to $349 immediately following the policy change, because the allowed charge per unit of rHuEPO was lower when payment became more dependent on the amount of rHuEPO administered with each treatment than when the payment was fixed at $40 per treatment. The average monthly allowed charge for rHuEPO increased to $375 in the sixth month following the change in payment policy as a result of the increase in dose and the new variable payment. The unadjusted and adjusted changes in mean hematocrit 6 months after the payment change were positive but clinically very small (0.3 and 0.2 percentage points, respectively).(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of azathioprine on response of renal anaemia to subcutaneous recombinant human erythropoietin

AIMS

To determine the effect of concomitant azathioprine treatment on the response of patients with renal failure to treatment with subcutaneous recombinant human erythropoietin (r-HuEPO).

METHODS

Two groups of patients with renal failure not receiving haemodialysis were studied. One comprised seven patients receiving erythropoietin alone, the second consisted of nine patients who were also treated with azathioprine. The haematological changes were monitored, and the functional erythropoietic response was studied by two different ferrokinetic models. One analysed the initial, the other the extended plasma iron clearance. Studies were performed before r-HuEPO treatment on all 16 patients, and repeated on 11 of these when the target haemoglobin (10-11 g/dl) was achieved and stabilised. Total erythropoiesis was determined using both techniques. Analysis of the extended plasma iron clearance also permitted calculation of both effective and ineffective erythroid activity.

RESULTS

The haematological response to r-HuEPO was the same for both patient groups. Measurement of total erythropoiesis by both ferrokinetic methods showed good correlation. For those receiving long term azathioprine, the percentage ineffective erythropoiesis was high compared with that of the other patients, and remained so for as long as they continued with azathioprine. For those uncomplicated by azathioprine treatment, r-HuEPO increased levels of both effective and ineffective erythropoiesis by the same degree. A substantial reduction in ineffective erythropoiesis was shown only by those patients who either discontinued or reduced their azathioprine once they started r-HuEPO treatment.

CONCLUSIONS

Azathioprine increases ineffective erythropoiesis. In this study, the r-HuEPO dose was sufficient to overcome this effect and promoted effective erythropoiesis so that the anaemia lessened. Measurement of total erythropoiesis provided limited information on the functional changes involved, differentiation of effective from ineffective erythropoiesis being necessary to define the changes after azathioprine reduction or withdrawal.

Regulation of iron absorption in iron loaded subjects with end stage renal disease: effects of treatment with recombinant human erythropoietin and reduction of iron stores

The effects on iron absorption of variation in erythroid activity, haemoglobin and iron stores were studied in six anaemic dialysis-dependent subjects in whom iron stores were increased from previous red cell transfusions. Gastrointestinal mucosal uptake and whole body retention of oral iron were measured at the beginning of the study, after starting treatment with recombinant erythropoietin (but before significant increase in haemoglobin), after partial correction of anaemia, after further reduction of iron stores by repeated phlebotomy, and when erythropoiesis decreased from the discontinuation of treatment with erythropoietin. Between successive measurements, valid comparisons were made in five subjects. Correction of anaemia decreased whole body retention of iron through decreased mucosal uptake (P = 0.032). Further reduction in iron stores through repeated phlebotomy whilst the increase in haemoglobin was maintained by treatment with erythropoietin, tended to increase whole body retention of iron through an increase in mucosal transfer (P = 0.010). With initial enhancement of erythropoiesis in anaemic iron-loaded subjects there was no change in any measured component of iron absorption. However, after correction of anaemia and reduction of iron stores, a decrease in erythropoiesis was associated with decreased whole body iron retention in all subjects through decreased mucosal transfer (P = 0.028). The data suggest that anaemia upregulates mucosal iron uptake, and that erythroid activity upregulates mucosal transfer but that this latter effect may be counter-balanced by iron overload which downregulates mucosal transfer.

Anemia of renal failure. Use of erythropoietin

Chronic renal failure is almost invariably accompanied by symptomatic anemia. It has been demonstrated that the primary cause of this anemia is inadequate production of erythropoietin by the diseased kidneys. The isolation of erythropoietin, followed by the cloning and expression of the human erythropoietin gene, made possible clinical trials of rHuEPO in uremic patients. rHuEPO produced dramatic increases in the hematocrit in almost all patients treated and also ameliorated many symptoms, such as lethargy, dizziness, and poor appetite, that had long been attributed to the effect of uremic toxins. Adverse effects of treatment with rHuEPO noted in the early clinical trials included hypertension, seizures, arteriovenous fistula or shunt thrombosis, and hyperkalemia. Further study of rHuEPO has shown that many of these side effects may be no more frequent in patients receiving rHuEPO than in other uremic patients not receiving rHuEPO. Reduction of the rHuEPO dosage and subcutaneous administration produce less rapid increases in the hematocrit and may lessen the incidence and severity of these side effects. rHuEPO therapy places great demands on both the body's iron stores and the capacity to rapidly transfer iron from storage sites to the erythroid progenitor cells. Thus, almost all patients treated with rHuEPO become iron deficient and require oral or parenteral iron replacement. Response to rHuEPO in uremic patients is diminished if the anemia is complicated by iron deficiency, inflammatory disorders, aluminum overload, or deficiency of folate or vitamin B12. rHuEPO therapy is safe and effective in the treatment of the anemia of chronic renal failure. The use of rHuEPO leads to enhanced quality of life and eliminates the need for red cell transfusions. In addition to hemodialysis patients, predialysis patients and those on CAPD benefit from and are candidates for rHuEPO therapy.

The treatment of anaemia in the myelodysplastic syndromes with recombinant human erythropoietin

Recombinant human erythropoietin was administered subcutaneously to 10 patients with myelodysplasia (MDS) who had haemoglobin concentrations less than 10 g/dl, in an attempt to relieve their anaemia. Doses of 60 units/kg/d rising to 90 units/kg/d were given over a maximum period of 16 weeks. Two out of 10 patients showed a steady rise in haemoglobin concentration during treatment. One patient with refractory anaemia had a sustained rise from 9.9 g/dl to 11.3 g/dl, and one patient with refractory anaemia with excess blasts (RAEB) had a rise from 9.5 g/dl to 11.4 g/dl but then relapsed with the development of an iron deficient state. Serum concentrations of immunoreactive EPO varied considerably between patients, but both responders had relatively low baseline levels. Both responders were also new diagnoses and had received no red cell transfusions. The criteria for response to recombinant human erythropoietin therapy, as well as the indications for therapy remain to be clarified.