Subcutaneous erythropoietin

The Pharmacokinetics of Intraperitoneal Erythropoietin Administered Undiluted Or Diluted in Dialysate

+ Objective

To compare the bioavailability of intraperitoneal erythropoietin (EPO) administered undiluted versus diluted in 2 L of dialysis fluid.

+ Design

Group 1 patients received one dose of EPO, 400 Ulkg BW given with vehicle only. This dwelled for 8 hours after which 2 L of dialysate were infused. Group 2 patients received the same dose of EPO diluted in 2 L of dialysate which dwelled for 8 hours. Both groups resumed their CAPD regimen after the first 8 hours. Blood levels of EPO were measured for 24 hours in both groups.

+Setting

The Home Peritoneal Dialysis Unit, Toronto Hospital, Western Division.

+ Patients

The participants were on CAPD for at least three months, free of peritonitis, and had no abnormalities of peritoneal transport. Three patients took part in both arms of the study, and there were 6 patients altogether in each group.

+ Results

When EPO was administered undiluted, there was a greater than ninefold increase in bioavailability of the hormone as measured by the area under the curve (AUC), compared to when the same dose was diluted in 2 L of dialysis fluid.

+ Conclusions

The previous studies that reported low bioavailability of intraperitoneal EPO used the hormone diluted in dialysate. The current findings suggest that if EPO is given in the dry peritoneal cavity, the bioavailability is greatly improved and may be clinically effective. Intraperitoneal instillation may prove to be an alternative route for EPO in the peritoneal dialysis patient unable or unwilling to receive subcutaneous injections. We are currently studying the effectiveness of undiluted intraperitoneal EPO in CAPD patients.

Comparative Pharmacokinetics of Recombinant Erythropoietin Administered by the Intravenous, Subcutaneous, and Intraperitoneal Routes in Continuous Ambulatory Peritoneal Dialysis (CAPD) Patients

The single dose pharmacokinetics of recombinant human erythropoietin (r-HuEPO) were compared in six continuous ambulatory peritoneal dialysis (CAPD) patients after intravenous (i.v.), subcutaneous (s.c.), and intraperitoneal (i.p.) administration of 300 U/kg. Intravenous administration gave results close to those obtained in hemodialysis patients, with a half-life of 11.2 h and a volume of distribution of 5.0% of body weight. After subcutaneous administration, the serum concentration rose slowly to plateau between 24 and 36 h, the area under the serum concentration vs. time curve from 6 to 72 h being 18.2% of that after intravenous administration. After intraperitoneal administration, the serum concentration was even lower, the area under the curve from 0 to 24 h was between 2.5 and 3.6% of that after intravenous administration, and 80% of the administered dose was recovered in the first peritoneal effluent after a 4- h dwell time.

Hematocrit Values in the CAPD/CCPO Population: A Report of the National CAPO Registry

A survey of the National CAPD Registry population was conducted to assess the distribution of hematocrit levels in a large group of peritoneal dialysis patients, to characterize the anemia of the population, and identify factors which relate to variation in hematocrit levels. A random sample of 812 patients was selected from the Registry population. Information was provided on 608 patients. Characteristics of sampled patients were similar to the Registry population as a whole. The mean hematocrit level in this cohort was 29.4% and the median was 29%. Recent peritonitis, time on CAPD, folate therapy, androgen therapy, and iron therapy had no obvious influence on hematocrit distributions. Significantly higher hematocrits were seen in males, whites, and patients with polycystic kidney disease. Significantly lower hematocrits were seen in surgically anephric patients and in patients who had received transfusions 60 days before the survey. Eighty-nine percent of patients had not received a transfusion 60 days prior to the survey. Some patients, especially those with hematocrits below the median, might benefit from recombinant erythropoietin therapy.

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.

The use of recombinant human erythropoietin in humans

Recombinant human erythropoietin (rhEPO) has now been in clinical trials for over three years. It has been shown to be nearly uniformly effective in correcting the anaemia of patients on haemodialysis or patients with progressive chronic renal failure not yet on dialysis. Preliminary results indicate that rhEPO is effective in increasing the ability of individuals to donate blood for self-use and early trials have shown the drug to increase the haematocrit in patients with rheumatoid arthritis. Trials in patients with anaemia associated with cancer or myelodysplastic syndromes are warranted. rhEPO will have a major impact as a therapeutic, particularly in patients with renal disease.

Randomized cross-over comparison of intravenous and subcutaneous darbepoetin dosing efficiency in haemodialysis patients

BACKGROUND

Studies have consistently shown the superior dosing efficiency of subcutaneous (s.c.) compared to intravenous (i.v.) erythropoietin (r-HuEPO). Unlike r-HuEPO, data from pivotal darbepoetin trials support s.c. and i.v. dosing equivalence, however, no blinded cross-over randomized studies of s.c. and i.v. dose efficiency or intra-patient variability in response have been published.

METHODS

During this 12-month study, 53 haemodialysis patients were randomized to s.c. or i.v. darbepoetin for a 6-month period and then switched to the alternative route for a second 6-month period. Darbepoetin dose was titrated during the first 4-months of each period to achieve a stable haemoglobin during the final 2-month observation period of each arm.

RESULTS

Twenty-four patients were included in analysis. No significant difference between s.c. and i.v. administration was observed for any measured parameter. Patients achieved a non-significantly higher haemoglobin (123.6 +/- 3.76 vs 120.9 +/- 4.42 g/L, P = 0.11) from a non-significantly lower darbepoetin dose (40.8 +/- 10.7 vs 42.5 +/- 11.0 mcg/week, P = 0.23) with i.v. administration. The population-based weight normalized s.c./i.v. dose ratio was 1.04 (0.97-1.11). Despite no significant overall difference, some patients experienced changes in individual dose efficiency response. Three of 24 patients recorded a greater than 30% change, four of 24 recorded between a 20 and 30% change, and five of 24 patients recorded between a 10 and 20% change relative to i.v. dose efficiency.

CONCLUSIONS

This study further supports s.c. and i.v. dosing equality and that overall the more convenient i.v. route can be used with equal dosing efficiency. However, patients switching routes of administration should be monitored due to the wide range in individual response.

The efficacy of once weekly compared with two or three times weekly subcutaneous epoetin beta: results from a randomized controlled multicentre trial. Swedish Study Group

BACKGROUND

Anaemia in haemodialysis patients can be effectively treated with erythropoietin. We investigated whether subcutaneous (SC) epoetin ss administered once weekly was as effective as the same weekly dosage given in two to three divided doses.

METHODS

One hundred and fifty-eight patients (delivered Kt/V >1.0, where K=dialyser-renal urea clearance, t=dialysis time and V=filtration volume, obtained by urea kinetic modelling) were randomized to treatment with SC epoetin beta either once weekly (n=118), or to their original dosage two or three times weekly (control group, n=40) for 24 weeks. All patients received intravenous iron supplementation when necessary.

RESULTS

Eight-eight patients in the once weekly group and 30 patients in the control group were treated for at least 16 weeks and are included in the analysis. Stable haemoglobin levels were maintained without epoetin dose increases in 73% of patients in both groups. Mean haemoglobin levels at randomization and after 16 and 24 weeks were 11.4, 11.1 and 11.1 g/dl, respectively, in the once weekly group compared with 11.2, 11.3 and 11.2 g/dl, respectively, in the control group. The mean weekly epoetin beta dosages at randomization and after 16 and 24 weeks were 102, 103 and 106 IU/kg bodyweight, respectively, in the once weekly group compared with 109, 109 and 115 IU/kg bodyweight, respectively, in the control group. No statistically significant between-group differences were apparent for changes in haemoglobin levels or epoetin beta dosages at week 24.

CONCLUSIONS

Once weekly SC administration of epoetin beta is as safe and effective in maintaining haemoglobin levels in stable haemodialysis patients as two or three times weekly administration of the same total dose. By using the once weekly regimen, patients can avoid up to 104 injections per year. This would reduce clinic time for patients who do not self administer, and may also encourage self-administration and improve overall compliance.

Comparison between intravenous and subcutaneous recombinant human erythropoietin (Epoetin alfa) administration in presurgical autologous blood donation in anemic rheumatoid arthritis patients undergoing major orthopedic surgery

BACKGROUND AND OBJECTIVES

Intravenous (i.v.) Recombinant erythropoietin (Epoetin alfa) is effective in allowing autologous blood donation in patients unable to donate because of anemia. We undertook this open pilot study in order to asses whether a low subcutaneous (s.c.) dose of Epoetin alfa would prove as effective and well tolerated as the higher i.v. dose. Such a move would also decrease costs.

MATERIALS AND METHODS

A total Epoetin alfa s.c. dose of 800 IU/kg was compared with a total i.v. dose of 1,800 IU/kg. Twenty-two rheumatoid arthritis patients, unable to donate because of hemoglobin (Hb) < 11 g/dl, received 300 IU/kg of IV Epoetin alfa twice weekly for 3 weeks (11 patients), or 100 IU/kg of s.c. Epoetin alfa twice weekly for 3 weeks plus an i.v. bolus of 200 IU/kg of Epoetin alfa at the first visit (11 patients). At each visit, all patients received 100 mg of i.v. iron saccharate and when the hematocrit (hct) > or = 34%, 350 ml of autologous blood (AB) were collected.

RESULTS

No significant differences were observed between the 2 groups of treated patients in terms of units of AB collected (2.6 +/- 0.6 vs. 2.5 +/- 0.5 units for i.v. and s.c. groups, respectively), ml of RBC produced during the study period (291 +/- 99 vs. 337 +/- 65 ml for the i.v. and s.c. groups, respectively), or in the degree of reduced exposure to allogeneic blood in comparison with the control group.

CONCLUSIONS

Lower dose of Epoetin alfa (reduced by 56%), supplemented by i.v. iron, is as effective and well tolerated as higher doses administered i.v., supplemented by i.v. iron.

Must erythropoietin be injected by the subcutaneous route for every hemodialyzed patient?

A multicenter, prospective, and controlled trial was performed to evaluate the efficacy and tolerance of intravenous (i.v.) and subcutaneous (s.c.) recombinant erythropoietin (rH-EPO) administration routes in 49 long-term hemodialyzed patients on maintenance phase of treatment, to determine the usefulness of replacing i.v. route by SC route in all of them. Each of these patients had already been treated with rH-EPO by the i.v. route for at least 6 months and included in the protocol on stabilized consumption phase. We arbitrarily chose three strata according to previous needs: Stratum A (> 150 U/kg/week) for eight patients, Stratum B (100 to 150 U/kg/week) for 12 patients, and Stratum C (< 100 U/kg/week) for 29 patients. In each stratum, the further treatment route (i.v. or s.c.) was randomized. Finally, 25 patients continued with i.v. route, and the other 24 changed to the s.c. route. The objective was to maintain a stable hemoglobin level, ranging from 9 to 10 g/dL. Tolerance and consumption in each group (i.v. and s.c.) were compared 4 months later. Globally, for an identical efficacy, rH-EPO needs were lesser using s.c. route (84 U/kg/week) than i.v. route (112 U/kg/week) (P = 0.02). However, when the strata were studied, it transpires that this benefit existed only for consumers having the highest needs (Stratum A) and not for the others. With regard to tolerance, only thrombotic events might be less frequent by using s.c. route, but the significance threshold is not reached (P = 0.09). Thus, replacing i.v. route by SC route, especially in high consumers, reduces the cost of treatment by rH-EPO. This benefit might be dependent on previous needs.

Erythropoiesis, erythropoietin, and iron metabolism in elective surgery: preoperative strategies for avoiding allogeneic blood exposure

Preoperative autologous donation (PAD) of blood and administration of recombinant human erythropoietin (Epoetin alfa) are two strategies for increasing red blood cell (RBC) mass preoperatively. The success of PAD depends primarily on the patient's ability to manufacture new RBCs before surgery to replace those removed during PAD. Red blood cell manufacture depends in turn on adequate supplies of iron and the increased renal production of endogenous erythropoietin following PAD. Successful PAD also requires adequate time for regeneration of predonated RBCs. Parenteral administration of Epoetin alfa causes a dose-dependent stimulation of RBC production. Its use has been studied as an adjunct to PAD and as a method to enhance endogenous erythropoiesis without PAD. Several studies suggest that administration of Epoetin alfa, begun several days before surgery, may stimulate erythropoiesis and help decrease the number of RBC transfusions required postoperatively. The precise role of Epoetin alfa in the surgical setting is not yet established, and optimal dosage regimens have not been determined.

Ultrasound-mediated transdermal protein delivery

Transdermal drug delivery offers a potential method of drug administration. However, its application has been limited to a few low molecular weight compounds because of the extremely low permeability of human skin. Low-frequency ultrasound was shown to increase the permeability of human skin to many drugs, including high molecular weight proteins, by several orders of magnitude, thus making transdermal administration of these molecules potentially feasible. It was possible to deliver and control therapeutic doses of proteins such as insulin, interferon gamma, and erythropoeitin across human skin. Low-frequency ultrasound is thus a potential noninvasive substitute for traditional methods of drug delivery, such as injections.

Differences in intravenous and subcutaneous application of recombinant human erythropoietin: a multicenter trial

The aims of this clinical study were to compare the maintenance doses for intravenous (i.v.) and subcutaneous (SC) administration of recombinant human erythropoietin (rhEPO) and to investigate whether there is any difference in the increase of the packed cellular volume (PCV) per week under i.v. and SC administration of rhEPO from two production sites (Genetics Institute, Cambridge, USA; and Boehringer Mannheim, Penzberg, Germany). A total of 90 patients suffering from end-stage renal disease were included in the study. All patients had already been treated for at least 6 months with chronic hemodialysis. The study was carried out as a randomized, multicenter parallel group comparison study with a 1-week pretreatment phase, a subsequent 8-week double-blind phase, and a final open phase. The final open phase consisted of a correction phase and a maintenance phase. The production site had no influence on the PCV increase per week, and there were no differences with respect to tolerability. The median rhEPO dose required to maintain the target PCV of 30 to 35 vol.% was 33 U/kg body weight three times a week in the i.v. group compared with 22 U/kg in the SC group (i.e., an average of 30% less with SC administration). Development or aggravation of hypertension under rhEPO therapy was observed, especially during the correction phase and more frequently in the SC group than in the i.v. group. During the maintenance phase, there was no essential difference between the two groups.

Efficacy of different dosing regimens for recombinant human erythropoietin in a simulated perisurgical setting: the importance of iron availability in optimizing response

PURPOSE

The goal of this study was to develop a short-term, practical, yet effective regimen for the perioperative use of recombinant human erythropoietin (r-HuEPO) as an alternative to autologous blood donation and/or homologous transfusion. In addition, changes in iron kinetics during accelerated erythropoiesis were examined.

PATIENTS AND METHODS

A randomized trial was performed on 24 healthy, iron-replete men. Subjects were given r-HuEPO in one of three dosage schedules, receiving a total dose of 1200 U/kg r-HuEPO subcutaneously: Group I--300 U/kg on Days 1, 4, 7, and 10; Group II--400 U/kg on Days 1, 5, and 9; Group III--600 U/kg on Days 1 and 10. All subjects received 300 mg of elemental iron orally each day for 10 days beginning on Day 1. Complete blood counts (CBC), absolute reticulocyte counts, serum ferritin, serum iron, serum total iron-binding capacity (TIBC), and serum transferrin receptor protein concentrations were measured periodically during the 24-day study period.

RESULTS

All groups showed a statistically significant increase in hematocrit, hemoglobin, and absolute reticulocyte count. There was no significant difference in response among the three groups with respect to hemoglobin and hematocrit. The mean maximum increases in hematocrit were 5.4 +/- 1.7, 6.0 +/- 2.1, and 7.2 +/- 2.6 in groups I, II, and III, respectively. The increase in hematocrit positively correlated with log baseline ferritin (r = 0.682, p < 0.001). Administration of r-HuEPO was associated with a highly significant (p < or = 0.0005) 74% decrease in serum ferritin, as well as a marked decrease in percent saturation of TIBC from 39% +/- 14% to 14% +/- 4% (p < or = 0.0005). This was despite the fact that subjects lost less than 250 mL of blood as a result of venipunctures during the entire course of the study.

CONCLUSION

Each of these r-HuEPO dose schedules provides an effective, convenient regimen for perisurgical use. However, "normal" iron stores for basal erythropoiesis may not always be sufficient to supply optimal amounts of iron for the accelerated erythropoiesis associated with acute r-HuEPO administration, even with oral iron supplementation. Nonetheless, these findings provide support for further study of the use of r-HuEPO as an alternative to autologous blood donation in the perisurgical setting.

Pharmacokinetics of epoetin in haemodialysis patients after subcutaneous administration: influence of chronic treatment

The purpose of this study was to investigate whether chronic subcutaneous administration of epoetin has an influence on its pharmacokinetics in patients with chronic renal failure and anaemia. 14 Patients were included in the study. The data of 8 patients could be evaluated at the end of the study. All patients were on maintenance haemodialysis. The pharmacokinetic profile of epoetin was studied directly after the first subcutaneous administration of 60 U/kg body weight. Patients were further treated with epoetin to maintain haemoglobin concentration between 6.0 and 6.5 mmol/l. After about one year of treatment the pharmacokinetic profile was studied again, using the same dosage. Between both profiles no significant differences (paired Student's t-test) were found in the pharmacokinetic parameters studied: absorption half-life, time to maximum concentration, maximum concentration, elimination half-life, area under the curve and mean residence time. However, in individual patients large differences may be found.

Pharmacokinetics of intraperitoneal, intravenous, and subcutaneous recombinant human erythropoietin in patients on continuous ambulatory peritoneal dialysis

The pharmacokinetics of recombinant human erythropoietin (Epo) were compared after mean single 99.1 U/kg intraperitoneal (IP), intravenous (i.v.), and subcutaneous (SC) doses in eight noninfected patients on peritoneal dialysis in a randomized, three-way, cross-over fashion. Continuous ambulatory peritoneal dialysis was performed in all patients on the days of the study. The IP dose was instilled into an empty peritoneum; total dwell time was 10 hours (4 hours dry, 6 hours with 2 L of peritoneal dialysis fluid). Blood samples were collected for 96 hours following IP and SC Epo, and for 72 hours following i.v. Epo. For the IP dose, a 10-hour effluent dialysate sample was collected to determine Epo recovery. Enzyme immunoassay was used for Epo analysis. The mean apparent volume of distribution was 0.05 L/kg, equivalent to 4.5% of total body weight; the mean total body clearance was 0.08 mL/min/kg. All eight patients exhibited multiexponential decay in serum Epo concentrations following i.v. Epo. Absorption of IP Epo was significantly greater than previous reports, presumably due to its administration into a dry peritoneum. The maximum concentrations following the IP and SC doses were nearly identical, but amounted to only 5% of the maximum concentrations for the i.v. dose. Subcutaneous Epo took nearly twice as long as IP Epo to achieve peak serum concentrations (17.1 +/- 5.0 hours v 9.4 +/- 1.9 hours). Compared with the IP route, the SC dose achieved a higher area under the serum concentration time curve from time 0 to 96 hours (AUC0-96; P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics and hematologic response to subcutaneous administration of recombinant human erythropoietin in children undergoing long-term peritoneal dialysis: a multicenter study

For a study of the pharmacokinetics and hematologic response of subcutaneously administered recombinant human erythropoietin (rHuEPO), 24 children (mean age, 10 years 3 months; range, 3 months to 18 years) maintained by peritoneal dialysis and with anemia caused by end-stage renal failure (mean hemoglobin level, 6.5 gm/dl; range, 4.7 to 7.9) were treated with rHuEPO administered subcutaneously at an initial dose of 25 IU/kg twice per week. After a 4-week interval, in the case of no response (hemoglobin increase < or = 1 to 1.5 gm/dl per month) the rHuEPO dosage was increased every 4 weeks according to the following schedule: 50, 75, 100, and 150 IU/kg twice per week. The administration of rHuEPO produced a rapid increase in serum concentration with a mean peak level of 59.8 mU/ml after 9 hours. Mean area under the curve to 72 hours was 2020 mU/ml per hour (range, 568 to 6609); mean elimination half-life and mean residence time were, respectively, 25.2 hours (range, 6.2 to 58.7) and 42.0 hours (range, 10.9 to 96). Of 24 children entered in the study, six had the drug suspended early because of renal transplantation (n = 1), lack of compliance (n = 4), or severe worsening of hypertension (n = 1). Eighteen patients had increased hemoglobin levels (to 9.4 +/- 1.7 gm/dl after 24 weeks of treatment). No correlation was found between the increase in hemoglobin concentration and any of the pharmacokinetic data or the peak erythropoietin level reached during the kinetic profile. Eight children required an increase of antihypertensive medications to maintain satisfactory blood pressure values. We conclude that low doses of subcutaneously administered rHuEPO slowly release the drug into the blood and satisfactorily increase hemoglobin levels with very few side effects.

Benefits and costs of recombinant human erythropoietin for end-stage renal failure: a review. Benefits and costs of erythropoietin

Recombinant human erythropoietin is an efficacious therapy in treatment of the anemia of end-stage renal failure. However, the scale of impact on quality of life and medical care resources remains uncertain. By reviewing the literature we evaluate cost-effectiveness of recombinant human erythropoietin and show how previous studies may have implicitly overestimated cost-effectiveness.

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.

Clinical application of recombinant human erythropoietin for treatments in patients with head and neck cancer

The therapeutic effects of intravenous recombinant human erythropoietin (r-hEPO) administration on anemia induced by radiation therapy (3 cases), chemotherapy (18 cases) and combined therapies (5 cases) in patients with head and neck malignancies were examined. The effectiveness was evaluated by the changes in the hemoglobin concentration examined before and after the r-hEPO administration. The r-hEPO administration combined with anticancer therapies improved anemia induced by all three treatments. The therapeutic effectiveness of r-hEPO injection was also noted on anemia induced by all of four different chemotherapeutic regimens that have been ordinarily used for head and neck malignancies. Furthermore, the efficacy of the different dose schedules, 3000 IU (12 cases) or 6000 IU (14 cases), three times a week, was compared. Both of the r-hEPO dose schedules were effective for anemia, but the efficacy of 6000 IU was superior to that of 3000 IU. No significant changes were observed in the number of white blood cells and platelets and the results of biochemical examinations after the r-hEPO injection. There were no objective side-effects related to the r-hEPO administration. These results suggest that anemia induced by chemotherapy and/or radiotherapy could be prevented by r-hEPO administration. The addition of r-hEPO to anticancer therapies would make it possible to pursue the planned therapeutic schedules, prevent the decrease of immunity after allogeneic blood transfusion and bring about an-improvement in the prognosis of patients with malignancies.

Subcutaneous use of erythropoietin in heart surgery

The effect of subcutaneous administration of recombinant human erythropoietin (rHuEPO) in ameliorating anemia resulting from autologous blood donation was compared with intravenous administration of rHuEPO. Forty patients undergoing coronary artery bypass procedures were divided into three groups. Group I (12 patients) received intravenous administration of rHuEPO (100 U.kg-1.day-1) and intravenous iron preparations for 14 days before operation; group II (14 patients) had subcutaneous administration of rHuEPO (600 U/kg) on preoperative days 14 and 7 and oral iron preparations for 14 days; and group III (14 patients) received oral iron preparations alone and served as the controls. Each patient predonated 800 mL of blood in the 2 weeks before operation. The reticulocyte count increased significantly in groups I and II (p less than 0.01), but little in group III. The hemoglobin level just before operation was higher in groups I (p less than 0.01) and II (p less than 0.05) compared with group III. Four patients (29%) in group III required homologous blood transfusion versus none in groups I and II (p less than 0.05). Subcutaneous administration of rHuEPO once a week was as effective as daily intravenous administration. Preoperative autologous blood donation can be performed over a short period on an outpatient basis with subcutaneous administration of rHuEPO.

Hemopoietic growth factors: a review

The hemopoietic growth factors are peptide hormones that are known to be responsible for the in vitro and in vivo proliferation of bone marrow progenitor cells into mature differentiated cells. These cytokines have had a major impact on the management of patients with cytopenias and have been extensively used as an adjunct to the management of patients with hematologic malignancies, with or without prior intensive chemotherapy. Other potential uses, being rigorously studied, include the potential mobilization of stem cells as well as recruitment phase-specific cells into the cell cycle, thus providing a more sensitive environment for targeting specific chemotherapeutic agents.

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.

Cost benefits of low dose subcutaneous erythropoietin in patients with anaemia of end stage renal disease

OBJECTIVE

To assess the cost benefits of low dose subcutaneous recombinant human erythropoietin in correcting the anaemia of end stage renal disease.

DESIGN

Three year retrospective study.

SETTING

Subregional nephrology service serving a mixed urban and rural population of 800,000.

SUBJECTS

60 patients with symptoms of anaemic end stage renal disease treated with erythropoietin (43 receiving haemodialysis; 11 receiving continuous ambulatory peritoneal dialysis; two with predialysis end stage renal disease; four with failing renal transplants).

MAIN OUTCOME MEASURES

Costs and savings of achieving and maintaining a haemoglobin concentration of 85-105 g/l with erythropoietin.

RESULTS

All patients treated with erythropoietin achieved the target haemoglobin concentration at median induction doses of 97 (95% confidence interval 95 to 108) units/kg/week, and this was maintained with 79 (75 to 95) units/kg/week at an average annual cost per patient of 2260 pounds. Admissions related to anaemia were virtually eliminated (246 v 1 inpatient days for 12 months before and after starting erythropoietin). 54 patients required no blood transfusions after starting erythropoietin, and the total requirements fell from 230 to 21 units in the 12 months before and after starting erythropoietin. Iron stores were maintained with oral or intravenous iron. All patients reported increased wellbeing, appetite, and exercise capacity. Hypertension developed or worsened in 30 patients, resulting in hospital admissions in five patients, one of whom had seizures.

CONCLUSION

Low dose subcutaneous erythropoietin restores haemoglobin concentrations sufficiently to abolish blood transfusion requirements and reduce morbidity. The net cost of erythropoietin prescribed in this way (2260 pounds/patient/year) was largely offset by savings in costs of hospital admissions. The true annual cost to the NHS was around 1200 pounds per patient.

Serum erythropoietin levels in hemodialysed patients after administration of recombinant human erythropoietin

In anemic patients on regular hemodialysis (HD), correction of anemia with recombinant human erythropoietin (rHuEpo) administered intravenously (iv) or subcutaneously (sc) was followed over a 2-month period. Monitoring serum Epo post-dose concentrations after the first iv rHuEpo injection and following another regular injection after 2 months of therapy with rHuEpo iv in 9 patients showed that the Epo elimination half-life was reduced from 7.48 h to 4.68 h. In the same patients the initially low percentage of erythroblasts and mature erythroid progenitors increased during 2 months of rHuEpo therapy. Because Epo molecules bound to Epo receptors are internalized in target cells we suggest that the expansion of the Epo responsive cell pool could explain the shorted Epo elimination time after 2 months of rHuEpo treatment. By monitoring serum Epo concentration following sc rHuEpo injection in 7 HD patients it was found that the modest increase in serum Epo levels (30-60 mU/ml) was sufficient to correct anemia.

Weekly subcutaneous recombinant human erythropoietin corrects anemia of progressive renal failure

PURPOSE

The purpose of this study was to analyze data retrospectively from our use of weekly subcutaneous recombinant human erythropoietin (rHuEPO) in predialysis and peritoneal dialysis patients with anemia.

PATIENTS AND METHODS

All anemic patients with progressive renal failure (12 predialysis and seven home peritoneal dialysis) in whom subcutaneous rHuEPO therapy was begun at, or was reduced to, a weekly dose were studied retrospectively. Patients were not selected for, nor excluded from, these observations for any other reason. Hematocrit and endogenous creatinine clearance were monitored regularly, and no other new treatment for anemia was given except oral iron. Iron-deficiency anemia was considered improbable because of normal red blood cell mean corpuscular volume. Unfortunately, iron parameters were not monitored.

RESULTS

The hematocrit increased 4 to 9 percentage points in 4 to 13 weeks in all but two patients who were initially treated with weekly doses, and a hematocrit of 31% was achieved in these patients within 6 to 12 weeks. The mean effective dose to accomplish this was 150 U/kg. All but three patients could be maintained on weekly doses at a hematocrit of 31% or higher. The mean effective dose was 75 U/kg.

CONCLUSION

It is concluded that subcutaneous rHuEPO administered weekly can correct the anemia of predialysis and peritoneal dialysis patients. Weekly dosing is more convenient for patients and may be less costly for Medicare providers.

Efficacy of once weekly erythropoietin therapy in children on continuous ambulatory peritoneal dialysis

The efficacy of recombinant human erythropoietin (rHuEPO) on 10 anemic children undergoing continuous ambulatory peritoneal dialysis (CAPD) was evaluated. A mean dose of 93 U/kg of rHuEPO was given once a week for 24 weeks, either intravenously to 5 children or subcutaneously to the other 5. Anemia improved in all children by this therapy. The mean hemoglobin and hematocrit levels increased gradually but significantly from 6.9 g/dl and 20.2% to 9.4 g/dl and 30.1%, respectively, at the end of the study. Elevation of blood pressure or other side effects were not noted in any patient. The present study indicates that the once-a-week injection of rHuEPO by the intravenous or subcutaneous route is effective in children undergoing CAPD.

The role of cytokines in oncology

The availability of sufficient quantities of recombinant human cytokines and promising preclinical data have led to their introduction into clinical trials. Cytokines have potential as new therapeutic agents in a variety of hematological disorders as well as in solid tumors. Only a few of the still increasing number of these glycoprotein hormones have been studied in humans so far, either as single agents or in combination with chemotherapy and other cytokines. Their clinical effects, beneficial role in supportive care, and use in the treatment of certain cancer patients are reviewed.

Low-dose subcutaneous erythropoietin in continuous ambulatory peritoneal dialysis

We evaluated changes in hematocrit in patients on continuous ambulatory peritoneal dialysis (CAPD) before and after the administration of erythropoietin (EPO). Thirty-five patients were evaluated at the beginning of treatment with CAPD and after an average of 3.5 years on CAPD; mean hematocrit (Hct) rose from 25.4 +/- 5.4% to 28.1 +/- 6.7% (P less than 0.001). In the period before EPO administration 11 patients required a total of 44 transfusions (one patient needed 23 transfusions). Fifteen patients were started on subcutaneous erythropoietin 3,000 units 3 times a week and were followed for a mean period of 6.3 months. Hct rose from 23.8 +/- 1.8% to 25.2 +/- 2.4% (P less than 0.01) within the first 2 weeks and up to 27.5 +/- 3.7% (P less than 0.01) in the fourth week. By the eighth week the target Hct (30 to 35%) was reached. During the next 5 months the EPO doses were adjusted to each patient's needs ranging between 2,000 U per week to 4,000 U 3 times per week. Mild hypertension was the only side effect seen in some of the patients. In conclusion low dose subcutaneous EPO is effective in managing the anemia of patients on CAPD with only minor side effects.

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.

Effect of human recombinant erythropoietin on anaemia and dialysis efficiency in patients undergoing continuous ambulatory peritoneal dialysis

The effect of long-term treatment with human recombinant erythropoietin (rHuEPO) has been studied in nine end-stage renal disease patients on continuous ambulatory peritoneal dialysis (CAPD). RHuEPO was administered subcutaneously twice weekly in rising doses starting with 50 Ukg-1 body weight. After 3 months of rHuEPO haemoglobin increased from 77.7 +/- 3.2 to 112.7 +/- 5.6 g l-1 (P less than 0.03), haematocrit rose from 22.8 +/- 1.2 to 30.3 +/- 1.7% (P less than 0.01). A consistent decrease in ferritin concentration was observed during this time (P less than 0.05). After 12 months of rHuEPO treatment and increased oral iron supplementation the rises of haemoglobin and haematocrit remained stable without other significant haematological changes. The rHuEPO-induced rise in haematocrit was associated with an increased peritoneal ultrafiltration (UF) without change in diuresis and body weight. UF improved from 128 +/- 28 ml 4 h-1 dwell time to 273 +/- 45 ml 4 h-1 (P less than 0.03) within 3 months of rHuEPO treatment, and remained stable during the following study period (month 12: 253 +/- 43 ml 4 h-1, P less than 0.05). The rise in UF resulted in improved peritoneal clearances of creatinine, urea, potassium, and phosphate (P less than 0.05, month 3). No change was observed in serum urea, creatinine, calcium, and potassium. Serum phosphate increased throughout the first 6 months of rHuEPO (P less than 0.05). No severe adverse effects of rHuEPO treatment could be observed. The present results demonstrate that long-term subcutaneous administration of rHuEPO is effective in correcting renal anaemia in CAPD patients and may improve dialysis efficiency by increased peritoneal ultrafiltration.

The use of erythropoietin in renal failure

The treatment of renal anaemia by recombinant human erythropoietin (EPO) is now well established. Several studies have examined the pharmacokinetics and efficacy of the drug given intravenously, intraperitoneally and subcutaneously and there is increasing evidence that the subcutaneous route has several advantages including the requirement for a lower dose. It is also important to stress the need for careful determination of baseline iron status of all patients before commencing EPO therapy. In the long term the extremely high iron stores of transfusion dependent patients will disappear. In the short term, however, the majority of the patients whose serum ferritin is less than 100 micrograms/l will require iron supplementation to allow an appropriate haemoglobin response. Alternatively, a fall in transferrin saturation to less than 20% is certainly an indication for iron supplementation and if oral iron therapy is not adequate then intravenous preparations may have to be considered. Although the anaemia of renal failure can be fully corrected by EPO, partial correction may be sufficient to reverse the problems of reduced exercise capacity, myocardial ischaemia and cardiomegaly which are frequently associated with end-stage renal disease. Partial correction will also result in a lesser rise in whole blood viscosity and, in turn, possibly reduce hypertension, thrombosis and increased peripheral resistance and thus lessen the side effects of EPO therapy.

Erythropoietin: its role in the regulation of erythropoiesis and as a therapeutic in humans

The application of recombinant DNA technology to the field of hematology has contributed greatly to our understanding of Epo gene structure and regulation, cellular expression and regulation of hormone production, pharmacokinetics, receptor biology, and ultimately, the value of this hormone as a therapeutic treatment. Areas that will undoubtedly prove fruitful for future research include the mechanisms by which hypoxia influences gene expression, structure/function relationships of the Epo molecule, mechanisms of transmembrane signaling and nuclear activation, and the application of rHuEpo in the treatment of other anemias. Epo is but one example of the contribution that modern biology has made to the understanding of hematopoietic regulation and to the availability of these regulators for the treatment of human disease.

Hematopoietic growth factors: overview and clinical applications, Part III

The growth and differentiation of blood cells is regulated by a group of at least 12 glycoproteins, collectively known as hematopoietic growth factors. Advances in protein biochemistry and molecular genetics have provided the tools for the bulk production of these hormones for clinical application. Clinical trials of macrophage colony-stimulating factor, granulocyte macrophage colony-stimulating factor, granulocyte colony-stimulating factor, and interleukin-3 have all demonstrated significant effects on the peripheral blood counts of the recipients. The clinical usefulness of at least two of these agents in ameliorating post-chemotherapy myelosuppression, in the treatment of other cytopenias, and in enhancing engraftment after bone marrow transplantation has already been demonstrated. Potential applications to the therapy and diagnosis of other clinical disorders is under study. The history of the elucidation of these growth factors, our current understanding of their properties, interactions, and clinical effects, and the potential prospects for their future use in the manipulation of human blood cell production are the subject of this review.

Treatment of the anemia of chronic renal failure with subcutaneous recombinant human erythropoietin

PURPOSE

The purpose of this study was to determine the efficacy of recombinant human erythropoietin (rHuEPO) given subcutaneously three times/week in patients with chronic renal failure and anemia (predialysis).

PATIENTS AND METHODS

Eleven patients with predialysis chronic renal failure participated in a double-blind, placebo-controlled study of subcutaneously administered erythropoietin. For 12 weeks, patients received either rHuEPO 100 mu/kg body weight three times/week subcutananeously or a placebo. After 12 weeks of placebo, patients now also received rHuEPO in a dose up to 150 mu/kg three times/week until target hematocrit was achieved. Throughout the study, blood pressure was monitored closely and blood work was obtained regularly for hemoglobin, hematocrit, reticulocyte count, and iron profile determinations.

RESULTS

At 12 weeks, the hematocrit of the treated group had risen from 29% +/- 2% to 35% +/- 2% (p less than 0.001). The placebo group baseline hematocrit was 28% +/- 2% and at 12 weeks 26% +/- 2% After 12 weeks of rHuEPO therapy, the hematocrit of the prior placebo group was 32% +/- 2% (p less than 0.001 versus baseline). No significant change in biochemical parameters was noted. Mean blood pressure values were comparable before and after treatment. All protein ultimately required iron supplementation. In two patients, the rate of progression of renal failure appeared to increase as their hematocrit rose and rHuEPO was discontinued.

CONCLUSIONS

It is concluded that rHuEPO given subcutaneously is an effective and safe therapy for patients with chronic renal failure who are anemic and who are not receiving dialysis.

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

Erythrokinetic studies were performed in subjects on continuous ambulatory peritoneal dialysis, during a trial examining the effectiveness of subcutaneous administration of recombinant human erythropoietin (r-HuEPO) in correcting the anaemia associated with end stage renal disease. 15 subjects (mean haemoglobin concentration 6.9 g/dl, SD 1.1) entered the study, and during treatment 9 were restudied at a haemoglobin concentration of 11-11.5 g/dl and six underwent a third study at haemoglobin 13-13.5 g/dl. By adjusting the dose of r-HuEPO, a stepwise increase in haemoglobin concentration was achieved, and this was accompanied by increases in total red cell volume and erythron transferrin uptake. Plasma volume decreased as red cell volume increased, leaving total blood volume essentially unchanged. Red cell survival, modestly reduced before treatment (mean 64, range 44-96 d, n = 6) tended to increase during treatment and when subjects were retested at a haemoglobin concentration of 13-13.5 g/dl (after 38-62 weeks treatment), the mean increase in red cell survival was 20 d (95% confidence interval 1-39 d). Thus subcutaneous r-HuEPO is effective in correcting the anaemia of end stage renal disease when administered thrice weekly to subjects on continuous ambulatory peritoneal dialysis. It produces an increase in haemoglobin concentration primarily by expanding the erythron, and may have a secondary effect, seen after several months of treatment, of increasing red cell survival.

Treating renal anaemia with recombinant human erythropoietin: practical guidelines and a clinical algorithm

Treatment with erythropoietin is highly effective and beneficial if given with care. In view of its cost, however, it is essential to exclude and treat other causes of anaemia before considering using this hormone. After treatment is started the important points for success are regular review of iron availability state combined with a slow correction of the anaemia. Failure of response requires a thorough search for a possible cause, which should be corrected before considering an increased dose of the hormone. Regular monitoring for potential complications, particularly a rise in blood pressure, is required.

Pharmacokinetics of recombinant human erythropoietin in chronic haemodialysis patients

Single dose intravenous and subcutaneous pharmacokinetics of recombinant human erythropoietin (rhEPO) has been determined in 6 chronic haemodialysis patients. Four patients, all on maintenance therapy with rhEPO, were consecutively treated both intravenously and subcutaneously with injections of rhEPO in a dose of 50 U/kg. Two previously untreated patients received 150 U/kg of rhEPO intravenously and subcutaneously. After intravenous injection of 50 U/kg of rhEPO a mean serum half-life value of 5.4 +/- 0.9 hr was found. The corresponding half-life after injection of 150 U/kg was 7.6 hr. The peak concentration of serum EPO after subcutaneous injection was 12.5-20 times lower than the corresponding intravenous Cmax. After administration of 150 U/kg subcutaneously the absorption of EPO was monitored to completion at 120 hr. The complete bioavailability of subcutaneous rhEPO after injection of 150 U/kg was 31.7%. Whether this low and protracted subcutaneous absorption of rhEPO is accounted for by either impeded absorption or partial skin degradation of rhEPO is not known.

The safety and the efficacy of maintenance therapy of recombinant human erythropoietin in patients with renal insufficiency

Ten anemic predialysis renal patients participated in a study to examine the long-term effects of recombinant human erythropoietin (r-HuEPO) treatment. The drug was initially given intravenously three times a week for 1 to 5 months, then by subcutaneous injections three times each week for 4 to 8 months, and finally by subcutaneous injection once weekly for 3 to 18 months. The duration of follow-up ranged from 11 to 29 months. Anemia was ameliorated in all participants. Mean hematocrit increased from a basal value of 26.8% to 35.1% during the intravenous phase and to 36.7% and 34.6% during the two subcutaneous periods. Mean weekly doses of erythropoietin (EPO) were 276 units/kg during intravenous therapy and 134 and 108 units/kg in the two subcutaneous periods. The differences in the doses were significant only between the intravenous and the two subcutaneous periods. Mean erythrocyte mass increased from a baseline value of 13.6 mL/kg to 20.4 mL/kg 8 months after initiation of treatment. Mean erythrocyte survival half-time was increased from 23 days before to 26 days, 8 months after r-HuEPO treatment, P less than 0.002. Mean blood pressure (mm Hg) was 105 before and 95 after treatment. Mean serum creatinine was 513 mumol/L (5.8 mg/dL) at the beginning of the study. At the time of this writing (11 to 29 months after treatment), seven patients have required dialysis treatment. There were three episodes of transient refractoriness to r-HuEPO documented during periods of infection and surgical procedures. All subjects tolerated the medication well, and no serious side effects attributable to the medication were noted. Furthermore, circulating antibodies against r-HuEPO were consistently negative.