Pharmacokinetics and effectiveness of recombinant erythropoietin administered to preterm infants by continuous infusion in total parenteral nutrition solution

Update on Erythropoiesis-Stimulating Agents Administered to Neonates for Neuroprotection

Erythropoiesis-stimulating agents (ESAs) such as erythropoietin and darbepoetin have been studied as red blood cell growth factors in preterm and term infants for more than 30 years. Recently, studies have focused on the potential neuroprotective effects of ESAs. In this review, we summarize preclinical animal models and recent clinical trials that provide evidence for ESAs as potential treatments to improve neurodevelopmental outcomes in preterm and term infants.

Early erythropoiesis-stimulating agents in preterm or low birth weight infants

BACKGROUND

Preterm infants have low plasma levels of erythropoietin (EPO), providing a rationale for the use of erythropoiesis-stimulating agents (ESAs) to prevent or treat anaemia and to provide neuro protection and protection against necrotising enterocolitis (NEC). Darbepoetin (Darbe) and EPO are currently available ESAs.

OBJECTIVES

To assess the effectiveness and safety of ESAs (erythropoietin (EPO) and/or Darbe) initiated early (before eight days after birth) compared with placebo or no intervention in reducing red blood cell (RBC) transfusions, adverse neurological outcomes, and feeding intolerance including necrotising enterocolitis (NEC) in preterm and/or low birth weight infants. Primary objective for studies that primarily investigate the effectiveness and safety of ESAs administered early in reducing red blood cell transfusions: To assess the effectiveness and safety of ESAs initiated early in reducing red blood cell transfusions in preterm infants. Secondary objectives: Review authors performed subgroup analyses of low (≤ 500 IU/kg/week) and high (> 500 IU/kg/week) doses of EPO and the amount of iron supplementation provided: none, low (≤ 5 mg/kg/d), and high (> 5 mg/kg/d). Primary objective for studies that primarily investigate the neuro protective effectiveness of ESAs: To assess the effectiveness and safety of ESAs initiated early in reducing adverse neurological outcomes in preterm infants. Primary objective for studies that primarily investigate the effectiveness of EPO or Darbe administered early in reducing feeding intolerance: To assess the effectiveness and safety of ESAs administered early in reducing feeding intolerance (and NEC) in preterm infants. Other secondary objectives: To compare the effectiveness of ESAs in reducing the incidence of adverse events and improving long-term neurodevelopmental outcomes.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 2), MEDLINE via PubMed (1966 to 10 March 2017), Embase (1980 to 10 March 2017), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to 10 March 2017). We searched clinical trials databases, conference proceedings, and reference lists of retrieved articles for randomised and quasi-randomised controlled trials.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of early initiation of EAS treatment versus placebo or no intervention in preterm or low birth weight infants.

DATA COLLECTION AND ANALYSIS

We used the methods described in the Cochrane Handbook for Systematic Reviews of Interventions and the GRADE approach to assess the quality of evidence.

MAIN RESULTS

This updated review includes 34 studies enrolling 3643 infants. All analyses compared ESAs versus a control consisting of placebo or no treatment. Early ESAs reduced the risk of 'use of one or more [red blood cell] RBC transfusions' (typical risk ratio (RR) 0.79, 95% confidence interval (CI) 0.74 to 0.85; typical risk difference (RD) -0.14, 95% CI -0.18 to -0.10; I² = 69% for RR and 62% for RD (moderate heterogeneity); number needed to treat for an additional beneficial outcome (NNTB) 7, 95% CI 6 to 10; 19 studies, 1750 infants). The quality of the evidence was low. Necrotising enterocolitis was significantly reduced in the ESA group compared with the placebo group (typical RR 0.69, 95% CI 0.52 to 0.91; typical RD -0.03, 95% CI -0.05 to -0.01; I² = 0% for RR and 22% for RD (low heterogeneity); NNTB 33, 95% CI 20 to 100; 15 studies, 2639 infants). The quality of the evidence was moderate. Data show a reduction in 'Any neurodevelopmental impairment at 18 to 22 months' corrected age in the ESA group (typical RR 0.62, 95% CI 0.48 to 0.80; typical RD -0.08, 95% CI -0.12 to -0.04; NNTB 13, 95% CI 8 to 25. I² = 76% for RR (high heterogeneity) and 66% for RD (moderate); 4 studies, 1130 infants). The quality of the evidence was low. Results reveal increased scores on the Bayley-II Mental Development Index (MDI) at 18 to 24 months in the ESA group (weighted mean difference (WMD) 8.22, 95% CI 6.52 to 9.92; I² = 97% (high heterogeneity); 3 studies, 981 children). The quality of the evidence was low. The total volume of RBCs transfused per infant was reduced by 7 mL/kg. The number of RBC transfusions per infant was minimally reduced, but the number of donors to whom infants who were transfused were exposed was not significantly reduced. Data show no significant difference in risk of stage ≥ 3 retinopathy of prematurity (ROP) with early EPO (typical RR 1.24, 95% CI 0.81 to 1.90; typical RD 0.01, 95% CI -0.02 to 0.04; I² = 0% (no heterogeneity) for RR; I² = 34% (low heterogeneity) for RD; 8 studies, 1283 infants). Mortality was not affected, but results show significant reductions in the incidence of intraventricular haemorrhage (IVH) and periventricular leukomalacia (PVL).

AUTHORS' CONCLUSIONS

Early administration of ESAs reduces the use of red blood cell (RBC) transfusions, the volume of RBCs transfused, and donor exposure after study entry. Small reductions are likely to be of limited clinical importance. Donor exposure probably is not avoided, given that all but one study included infants who had received RBC transfusions before trial entry. This update found no significant difference in the rate of ROP (stage ≥ 3) for studies that initiated EPO treatment at less than eight days of age, which has been a topic of concern in earlier versions of this review. Early EPO treatment significantly decreased rates of IVH, PVL, and NEC. Neurodevelopmental outcomes at 18 to 22 months and later varied in published studies. Ongoing research should evaluate current clinical practices that will limit donor exposure. Promising but conflicting results related to the neuro protective effect of early EPO require further study. Very different results from the two largest published trials and high heterogeneity in the analyses indicate that we should wait for the results of two ongoing large trials before drawing firm conclusions. Administration of EPO is not currently recommended because limited benefits have been identified to date. Use of darbepoetin requires further study.

Early erythropoiesis-stimulating agents in preterm or low birth weight infants

BACKGROUND

Preterm infants have low plasma levels of erythropoietin (EPO), providing a rationale for the use of erythropoiesis-stimulating agents (ESAs) to prevent or treat anaemia and to provide neuro protection and protection against necrotising enterocolitis (NEC). Darbepoetin (Darbe) and EPO are currently available ESAs.

OBJECTIVES

To assess the effectiveness and safety of ESAs (erythropoietin (EPO) and/or Darbe) initiated early (before eight days after birth) compared with placebo or no intervention in reducing red blood cell (RBC) transfusions, adverse neurological outcomes, and feeding intolerance including necrotising enterocolitis (NEC) in preterm and/or low birth weight infants. Primary objective for studies that primarily investigate the effectiveness and safety of ESAs administered early in reducing red blood cell transfusions:To assess the effectiveness and safety of ESAs initiated early in reducing red blood cell transfusions in preterm infants. Secondary objectives:Review authors performed subgroup analyses of low (≤ 500 IU/kg/week) and high (> 500 IU/kg/week) doses of EPO and the amount of iron supplementation provided: none, low (≤ 5 mg/kg/d), and high (> 5 mg/kg/d). Primary objective for studies that primarily investigate the neuro protective effectiveness of ESAs:To assess the effectiveness and safety of ESAs initiated early in reducing adverse neurological outcomes in preterm infants. Primary objective for studies that primarily investigate the effectiveness of EPO or Darbe administered early in reducing feeding intolerance:To assess the effectiveness and safety of ESAs administered early in reducing feeding intolerance (and NEC) in preterm infants. Other secondary objectives:To compare the effectiveness of ESAs in reducing the incidence of adverse events and improving long-term neurodevelopmental outcomes.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 2), MEDLINE via PubMed (1966 to 10 March 2017), Embase (1980 to 10 March 2017), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to 10 March 2017). We searched clinical trials databases, conference proceedings, and reference lists of retrieved articles for randomised and quasi-randomised controlled trials.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of early initiation of EAS treatment versus placebo or no intervention in preterm or low birth weight infants.

DATA COLLECTION AND ANALYSIS

We used the methods described in the Cochrane Handbook for Systematic Reviews of Interventions and the GRADE approach to assess the quality of evidence.

MAIN RESULTS

This updated review includes 34 studies enrolling 3643 infants. All analyses compared ESAs versus a control consisting of placebo or no treatment.Early ESAs reduced the risk of 'use of one or more [red blood cell] RBC transfusions' (typical risk ratio (RR) 0.79, 95% confidence interval (CI) 0.74 to 0.85; typical risk difference (RD) -0.14, 95% CI -0.18 to -0.10; I2 = 69% for RR and 62% for RD (moderate heterogeneity); number needed to treat for an additional beneficial outcome (NNTB) 7, 95% CI 6 to 10; 19 studies, 1750 infants). The quality of the evidence was low.Necrotising enterocolitis was significantly reduced in the ESA group compared with the placebo group (typical RR 0.69, 95% CI 0.52 to 0.91; typical RD -0.03, 95% CI -0.05 to -0.01; I2 = 0% for RR and 22% for RD (low heterogeneity); NNTB 33, 95% CI 20 to 100; 15 studies, 2639 infants). The quality of the evidence was moderate.Data show a reduction in 'Any neurodevelopmental impairment at 18 to 22 months' corrected age in the ESA group (typical RR 0.62, 95% CI 0.48 to 0.80; typical RD -0.08, 95% CI -0.12 to -0.04; NNTB 13, 95% CI 8 to 25. I2 = 76% for RR (high heterogeneity) and 66% for RD (moderate); 4 studies, 1130 infants). The quality of the evidence was low.Results reveal increased scores on the Bayley-II Mental Development Index (MDI) at 18 to 24 months in the ESA group (weighted mean difference (WMD) 8.22, 95% CI 6.52 to 9.92; I2 = 97% (high heterogeneity); 3 studies, 981 children). The quality of the evidence was low.The total volume of RBCs transfused per infant was reduced by 7 mL/kg. The number of RBC transfusions per infant was minimally reduced, but the number of donors to whom infants who were transfused were exposed was not significantly reduced. Data show no significant difference in risk of stage ≥ 3 retinopathy of prematurity (ROP) with early EPO (typical RR 1.24, 95% CI 0.81 to 1.90; typical RD 0.01, 95% CI -0.02 to 0.04; I2 = 0% (no heterogeneity) for RR; I2 = 34% (low heterogeneity) for RD; 8 studies, 1283 infants). Mortality was not affected, but results show significant reductions in the incidence of intraventricular haemorrhage (IVH) and periventricular leukomalacia (PVL).

AUTHORS' CONCLUSIONS

Early administration of ESAs reduces the use of red blood cell (RBC) transfusions, the volume of RBCs transfused, and donor exposure after study entry. Small reductions are likely to be of limited clinical importance. Donor exposure probably is not avoided, given that all but one study included infants who had received RBC transfusions before trial entry. This update found no significant difference in the rate of ROP (stage ≥ 3) for studies that initiated EPO treatment at less than eight days of age, which has been a topic of concern in earlier versions of this review. Early EPO treatment significantly decreased rates of IVH, PVL, and NEC. Neurodevelopmental outcomes at 18 to 22 months and later varied in published studies. Ongoing research should evaluate current clinical practices that will limit donor exposure. Promising but conflicting results related to the neuro protective effect of early EPO require further study. Very different results from the two largest published trials and high heterogeneity in the analyses indicate that we should wait for the results of two ongoing large trials before drawing firm conclusions. Administration of EPO is not currently recommended because limited benefits have been identified to date. Use of darepoetin requires further study.

Darbepoetin Administration in Term and Preterm Neonates

Erythropoiesis-stimulating agents (ESAs) such as erythropoietin have been studied as red cell growth factors in preterm and term infants for more than 20 years. Recent studies have evaluated darbepoetin (Darbe, a long-acting ESA) for both erythropoietic effects and potential neuroprotection. We review clinical trials of Darbe in term and preterm infants, which have reported significant erythropoietic uses and neuroprotective effects. ESAs show great promise in decreasing or eliminating transfusions, and in preventing and treating brain injury in term and preterm infants.

Early erythropoietin for preventing red blood cell transfusion in preterm and/or low birth weight infants

BACKGROUND

Low plasma levels of erythropoietin (EPO) in preterm infants provide a rationale for the use of EPO to prevent or treat anaemia.

OBJECTIVES

To assess the effectiveness and safety of early initiation of EPO or darepoetin (initiated before eight days after birth) in reducing red blood cell (RBC) transfusions in preterm and/orlow birth weight infants.

SEARCH METHODS

The Cochrane Library, MEDLINE, EMBASE, CINAHL, reference lists of identified trials and reviews, Pediatric Academic Societies Annual meetings 2000 to 2013 (Abstracts2View(TM)) and clinical trials registries (clinicaltrials.gov; controlled-trials.com; and who.int/ictrp) were searched in July 2013.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials of early (< eight days of age) initiation of EPO treatment versus placebo or no intervention in preterm and/or low birth weightinfants.

DATA COLLECTION AND ANALYSIS

The methods of the Neonatal Cochrane Review Group were used.

MAIN RESULTS

The updated review includes 27 studies enrolling 2209 infants. One study enrolling infants at a mean age of > eight days and one duplicate publication were excluded. One new study using darepoetin was identified.Early EPO reduced the risk of the 'use of one or more RBC transfusions' (typical risk ratio (RR) 0.79, 95% confidence interval (CI) 0.73 to 0.85; typical risk difference (RD) -0.14, 95% CI -0.18 to -0.10; I(2) = 54% for both; number needed to treat to benefit (NNTB) 7, 95% CI 6 to 10; 16 studies, 1661 infants).The total volume of RBCs transfused per infant was reduced (typical mean difference (MD) 7 mL/kg, 95% CI -12 to - 2; I(2) = 63%; 7 studies, 581 infants). The number of RBC transfusions per infant was minimally reduced (typical MD -0.27, 95% CI -0.42 to -0.12; I(2) = 64%; 13 studies, 951 infants). The number of donors to whom the infants were exposed was significantly reduced (MD-0.54, 95% CI -0.89 to -0.20; I(2) = 0%; 3 studies, 254 infants).There was a non-significant increase in the risk of stage ≥ 3 retinopathy of prematurity (ROP) with early EPO (typical RR 1.37, 95% CI 0.87 to 2.17; I(2) = 0%; typical RD 0.03, 95% CI -0.01 to 0.06; I(2) = 29%; 7 studies, 801 infants). A post hoc analysis including all studies that reported on ROP stage ≥ 3, regardless of the age of the infant when EPO treatment was started, showed a significantly increased typical RR of 1.48 (95% CI 1.02 to 2.13; P = 0.04; I(2) = 0%) and typical RD of 0.03 (95% CI 0.00 to 0.06; P = 0.03; I(2) = 50%; 10 studies, 1303 infants) with a number needed to treat to harm (NNTH) of 33 (95% CI 17 to infinity). In an Italian study in which the authors compared the use of early intravenous EPO with subcutaneous EPO the overall incidence of stage ≥ 3 was 15%, similar to the incidence of 17% in the study by Romagnoli and co-workers.The rates for mortality and morbidities including intraventricular haemorrhage and necrotizing enterocolitis were not significantly changed by early EPO treatment. Neurodevelopmental outcomes at 18 to 22 months varied.

AUTHORS' CONCLUSIONS

Early administration of EPO reduces the use of RBC transfusions, the volume of RBCs transfused, and donor exposure after study entry. The small reductions are likely to be of limited clinical importance. Donor exposure is probably not avoided since all but one study included infants who had received RBC transfusions prior to trial entry. In this update there was no significant increase in the rate of ROP (stage ≥ 3) for studies that initiated EPO treatment at less than eight days of age. In a post hoc analysis including all studies that reported on ROP stage ≥ 3 regardless of age at initiation of treatment there was an increased risk of ROP. The rates for mortality and morbidities including intraventricular haemorrhage and necrotizing enterocolitis were not significantly changed by early EPO treatment. Neurodevelopmental outcomes at 18 to 22 months vary in the studies published to date. Ongoing research should deal with the issue of ROP and evaluate current clinical practice that will limit donor exposure. Due to the limited benefits and the possibly increased risk of ROP, administration of EPO is not recommended. Darbepoetin requires further study. The possible neuroprotective role of EPO in neonates will be reviewed in separate Cochrane reviews.

How to administrate erythropoietin, intravenous or subcutaneous?

AIM

To determine whether adding recombinant erythropoietin to the intravenous (IV) solution and administering it as a 24-h continuous infusion would result in an erythropoietic effect not inferior to that seen with subcutaneous (SC) administration.

METHODS

Infants weighing ≤1500 grams and ≤32 weeks of gestational age were randomly assigned at 72 h of life to receive erythropoietin (300 units/kg, 3 times a week until 36 complete weeks of postmenstrual age or discharge), either subcutaneously [erythropoietin subcutaneous (ESC) group] or added to IV fluids [erythropoietin intravenous (EIV) group].

RESULTS

One hundred infants were randomized (50 in the EIV group and 50 in the ESC group). The incidence of transfusions was comparable in the two groups, similar in baseline characteristics and haematologic values at study entry. Phlebotomy losses did not differ between groups, and at the end of the study, there were no differences in reticulocyte counts, transferrin saturation and ferritin. No differences in the incidence of side effects were observed.

CONCLUSIONS

In preterm infants, continuous intravenous administration of erythropoietin was not inferior to SC dosing.

Early erythropoietin for preventing red blood cell transfusion in preterm and/or low birth weight infants

BACKGROUND

Low plasma levels of erythropoietin (EPO) in preterm infants provide a rationale for the use of EPO to prevent or treat anaemia.

OBJECTIVES

To assess the effectiveness and safety of early initiation of EPO in reducing red blood cell (RBC) transfusions in preterm and/or low birth weight infants.

SEARCH METHODS

The Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE, EMBASE, CINAHL, abstracts from scientific meetings published in Pediatric Research and reference lists of identified trials and reviews were searched through July 2009. Searches were repeated in March 2012 including searches of Pediatric Academic Societies Annual meetings 2000 to 2012 (Abstracts2View(TM)) and clinical trials registries (clinicaltrials.gov; controlled-trials.com; and who.int/ictrp).

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials of early (< eight days of age) initiation of EPO treatment versus placebo or no intervention in preterm and/or low birth weight neonates.

DATA COLLECTION AND ANALYSIS

Data collection and analysis were accomplished using the methods of the Neonatal Cochrane Review Group.

MAIN RESULTS

The May 2012 update did not identify any new studies for inclusion. A number of randomised controlled trials were excluded as they compared one EPO dosing regimen with another, did not provide the numbers of infants randomised to the EPO and the placebo group, or the dose of EPO was not stated. The update includes 27 studies that enrolled 2293 preterm infants. Early EPO reduced the risk of the "use of one or more RBC transfusions" [typical risk ratio (RR); 0.80 (95% confidence interval (CI) 0.75 to 0.86); typical risk difference (RD) -0.13, (95% CI -0.17 to -0.09); number needed to benefit (NNTB) = eight, (95% CI 6 to 11); 16 studies, 1,825 infants].There was moderate heterogeneity for this outcome [RR (P = 0.004; I(2) = 56.7%); RD (P = 0.003; I(2) = 56.0%)].A total of six studies enrolling 515 infants reported on the total volume of red blood cells transfused per infant. The significant typical mean difference (MD) was a reduction of 6 mL/kg of blood transfused (mL/kg) per infant (95% CI -11 to - 1). There was moderate heterogeneity for this outcome (P = 0.02; I(2) = 63.0%). The results from 14 studies enrolling 1131 infants reported on the number of red blood cell transfusions per infant. The significant typical MD for number of red blood cell transfusions per infant was -0.33, (95% CI -0.48 to -0.18). There was high heterogeneity for this outcome (P = 0.00001, I(2) = 78%). Two studies enrolling 188 infants reported on the number of donors to whom the infant was exposed; the MD was significantly reduced -0.63, (-1.07 to -0.19). There was no heterogeneity for this outcome (P = 0.59; I(2) = 0%).There was a significant increase in the risk of stage ≥ 3 retinopathy of prematurity (ROP) in the early EPO group [typical RR; 1.65, (95% CI 1.12 to 2.43); typical RD; 0.05 (95% CI 0.01 to 0.08); number needed to harm (NNTH); 20, (95% CI 13 to 100); eight studies, 984 infants]. There was no heterogeneity for this outcome for RR (P = 0.87; I(2) = 0%), but there was moderate heterogeneity for RD (P = 0.006; I(2) = 65%). The rates for mortality and other neonatal morbidities were not significantly changed by early EPO treatment nor were neurodevelopmental outcomes at 18 to 22 months in the small number of infants tested to-date.

AUTHORS' CONCLUSIONS

Early administration of EPO reduces the use of RBC transfusions and the volume of RBCs transfused. These small reductions are of limited clinical importance. Donor exposure is probably not avoided since most studies included infants who had received RBC transfusions prior to trial entry. There was a significant increase in the rate of ROP (stage ≥ 3). Early EPO does not significantly decrease or increase any of the other important adverse outcomes. Ongoing research should deal with the issue of ROP and evaluate the current clinical practice that will limit donor exposure. Due to the limited benefits and the increased risk of ROP, early administration of EPO is not recommended. Evidence is lacking for the possible neuro protective role of EPO in preterm infants. This topic will be reviewed in separate Cochrane reviews for preterm and term and late preterm infants.

A randomized, masked study of weekly erythropoietin dosing in preterm infants

OBJECTIVE

To compare reticulocyte responses of once-per-week erythropoietin (EPO) dosing with 3-times-a-week dosing in preterm infants.

STUDY DESIGN

Infants weighing ≤ 1500 g and ≥ 7 days of age were randomized to once-per-week EPO, 1200 U/kg/dose, or 3-times-a-week EPO, 400 U/kg/dose, subcutaneously for 4 weeks, along with iron and vitamin supplementation. Complete blood counts, absolute reticulocyte counts (ARCs), transfusions, phlebotomy losses, and adverse events were recorded.

RESULTS

Twenty preterm infants (962 ± 55 g, 27.9 ± 0.4 weeks, 17 ± 3 days of age) were enrolled. Groups were similar at baseline. Infants in both groups had increased ARCs, which were similar between treatment groups at the start and end of 4 weeks. Hematocrit remained stable, and similar numbers of transfusions were administered. No adverse effects of either dosing schedule were noted.

CONCLUSIONS

Preterm infants respond to weekly EPO by increasing ARCs and maintaining hematocrit. We speculate that once-per-week EPO dosing might be beneficial to preterm infants requiring increased erythropoiesis.

Erythropoietin in neonatal brain protection: the past, the present and the future

Over the last decade, neuroprotective effects of erythropoietin (Epo) and its underlying mechanisms in terms of signal transduction pathways have been defined and there is a growing interest in the potential therapeutic use of Epo for neuroprotection. Several mechanisms by which Epo provides neuroprotection are recognized. In this review, we focused on the neuroprotective mechanisms of Epo and provide a short overview on both experimental and clinical studies, testing Epo as a neuroprotective agent in the neonatal brain injury, and the safety concerns with the clinical use of Epo treatment in neonates.

Receptor-based dosing optimization of erythropoietin in juvenile sheep after phlebotomy

The primary objective of this work was to determine the optimal time for administration of an erythropoietin (Epo) dose to maximize the erythropoietic effect using a simulation study based on a young sheep pharmacodynamic model. The dosing optimization was accomplished by extending a Hb production pharmacodynamic model, which evaluates the complex dynamic changes in the Epo receptor (EpoR) pool from the changes in Epo clearance. Fourteen healthy 2-month-old sheep were phlebotomized to Hb levels of 3 to 4 g/dl. Epo clearance was evaluated longitudinally in each animal by administering tracer doses of (125)I-recombinant human Epo multiple times during the experiment. Kinetic parameters were estimated by simultaneously fitting to Hb data and Epo clearance data. The phlebotomy caused a rapid temporary increase in the endogenous Epo plasma level. The Hb began to increase after the increased in the Epo level with a lag time of 1.13 ± 0.79 days. The average correlation coefficients for the fit of the model to the Hb and clearance data were 0.953 ± 0.018 and 0.876 ± 0.077, respectively. A simulation study was done in each sheep with fixed individual estimated model parameters to determine the optimal time to administer a 100 U/kg intravenous bolus Epo dose. The optimal dose administration time was 11.4 ± 6.2 days after phlebotomy. This study suggests that the Hb produced from Epo administration can be optimized by considering the dynamic changes in the EpoR pool.

Comparison between one and three doses a week of recombinant erythropoietin in very low birth weight infants

OBJECTIVE

To compare transfusion requirements and erythropoietic response in preterms between schedules of rEPO administration once or three times per week, using the same weekly dose.

STUDY DESIGN

Prospective, randomized trial including infants weighing <1500 g at birth and/or were 32 weeks' gestation: Group 1 (60 infants) received subcutaneous rEPO at 250 units kg(-1) per dose, three times weekly for 6 weeks; Group 2 (59 infants), at 750 units kg(-1) per dose, once weekly for 6 weeks. Efficacy was evaluated based on the transfusion requirement, hemoglobin changes, reticulocyte counts, serum transferrin receptor (sTfR) and serum ferritin. The frequency of adverse effects was registered in both groups.

RESULT

A total of 13 infants were transfused in each group (relative risk: 0.98; 95% confidence interval: 0.4 to 2.3). Phlebotomy loss and red blood cell transfusion volumes received were similar in both groups. Hemoglobin levels were lower at end of study in Group 2 (10.6±1.5 g dl(-1) versus 11.5±1.4 g dl(-1); P<0.003). At end of study, reticulocyte counts and sTfR values increased and serum ferritin values decreased, without significant differences between the two groups. Incidence of complications was similar in both groups.

CONCLUSION

The once-weekly rEPO schedule for very low birth weight infants proved as effective as the three-times-weekly schedule, in relation to erythropoietic stimulus and transfusion requirement.

Pediatric Dosing and Body Size in Biotherapeutics

Although pediatric doses for biotherapeutics are often based on patients' body weight (mg/kg) or body surface area (mg/m²), linear body size dose adjustment is highly empirical. Growth and maturity are also important factors that affect the absorption, distribution, metabolism and excretion (ADME) of biologics in pediatrics. The complexity of the factors involved in pediatric pharmacokinetics lends to the reconsideration of body size based dose adjustment. A proper dosing adjustment for pediatrics should also provide less intersubject variability in the pharmacokinetics and/or pharmacodynamics of the product compared with no dose adjustment. Biological proteins and peptides generally share the same pharmacokinetic principle with small molecules, but the underlying mechanism can be very different. Here, pediatric and adult pharmacokinetic parameters are compared and summarized for selected biotherapeutics. The effect of body size on the pediatric pharmacokinetics for these biological products is discussed in the current review.

Erythropoietin for infants with hypoxic-ischemic encephalopathy

PURPOSE OF REVIEW

Perinatal asphyxia, intraventricular hemorrhage and stroke are common causes of neonatal brain injury, with hypoxia-ischemia as the final common pathway of injury. Erythropoietin (Epo) has potential to lessen neurologic sequelae due to hypoxia-ischemia. The purpose of this review is to highlight new clinical trials and experimental evidence that expand our understanding of Epo as a potential treatment for perinatal brain injury.

RECENT FINDINGS

Several trials of Epo treatment are reviewed: two phase I/II trials of high-dose Epo given to preterm infants established pharmacokinetic and safety profiles, and a trial of Epo treatment for term infants with moderate hypoxic-ischemic encephalopathy found reduced disability. Potential risks and benefits of high-dose Epo are discussed. New evidence related to Epo receptor expression, signal transduction pathways, and mechanisms of neuroprotection are reviewed.

SUMMARY

Cautious optimism is warranted regarding the use of high-dose Epo as a treatment option for neonatal brain injury. To date, Epo has been well tolerated to use in neonatal populations and now studies of neuroprotective efficacy are underway.

Erythropoietin increases reticulocyte counts and maintains hematocrit in neonates requiring surgery

BACKGROUND

Limited erythropoietin (Epo) production diminishes neonates' ability to regenerate blood removed by phlebotomy. Neonates requiring surgery are at risk to receive multiple transfusions. We sought to determine if recombinant Epo administration to neonates requiring surgery would stimulate erythropoiesis.

METHODS

Infants were randomized in double-masked fashion to receive Epo (200 units kg(-1) d(-1)) or placebo for 14 days. Complete blood count, absolute reticulocyte count (ARC), phlebotomy losses, and transfusions were measured during the study period. Infants were transfused using a strict transfusion protocol.

RESULTS

In the Epo group (n = 10, 2034 +/- 308 g, 8 +/- 2 days old; mean +/- SEM), ARC increased significantly, whereas in the placebo group (n = 10, 2400 +/- 184 g, 7 +/- 2 days old), ARC remained low. Hematocrits in the Epo group trended upward from 34.4 1.7% to 37.3 1.9% (although not statistically significant) despite phlebotomy losses of 53 +/- 12 mL/kg. Hematocrits in the placebo group were 35.9 1.8% and 33.2 1.6% on days 1 and 15, respectively, with phlebotomy losses of 27 +/- 5 mL/kg. There were no differences in absolute neutrophil counts or platelet counts between groups at the end of the study. No adverse effects were noted.

CONCLUSIONS

Infants randomized to Epo increased reticulocyte counts and hematocrits without adverse effects. Erythropoietin administration may provide an adjunct to present care in decreasing or eliminating erythrocyte transfusions in surgical neonates.

Pharmacokinetics and pharmacodynamics of intravenous epoetin alfa in children with cancer

BACKGROUND

Epoetin alfa (EPO, PROCRIT) pharmacokinetics and pharmacodynamics were evaluated in children with malignant solid tumors receiving chemotherapy.

PROCEDURE

Children initially received IV EPO 600 IU/kg (max dose 40,000 IU) or placebo once weekly for 16 weeks. Dose was increased to 900 IU/kg (max dose 60,000 IU) for patients not achieving a 1 g/dl increase in hemoglobin by study week 3 or 4. Serial PK samples were collected for 24 hr after the first study dose, and after the 10th or 11th dose. Serum EPO concentrations were analyzed using an ELISA assay, and pharmacokinetics were evaluated using compartmental methods.

RESULTS

Twelve children participated; six (median age 15.2 years; range 9.3-18.6 years) were randomized to receive EPO. All children required dosage increases to 900 IU/kg due to no response. The median (range) apparent EPO AUC0-24 and clearance (CL) were 67.1 IU/ml.hr (13.8-102.6) and 0.26 L/hr/m2 (0.19-1.08), respectively. After the 10th or 11th EPO dose in four of these six EPO patients, the median (range) apparent AUC0-24 and CL of EPO was 126.5 IU/ml.hr (107.3-161.1) and 0.21 L/hr/m2 (0.15-0.25), respectively. No significant correlations were observed between pharmacokinetic parameters and pharmacodynamic effects.

CONCLUSIONS

EPO disposition in our patients was similar to other pediatric patient populations or adults receiving IV EPO. Interesting but insignificant trends were noted in pharmacodynamic effects.

Early erythropoietin for preventing red blood cell transfusion in preterm and/or low birth weight infants

BACKGROUND

Hematocrit falls after birth in preterm infants due to physiological factors and blood letting. Low plasma levels of erythropoietin (EPO) in preterm infants provide a rationale for the use of EPO to prevent or treat anemia.

PRIMARY OBJECTIVE

To assess the effectiveness and safety of early initiation of EPO (initiated before eight days after birth) in reducing red blood cell transfusions in preterm and/or low birth weight infants.

SECONDARY OBJECTIVES

Subgroup analyses of low (< 500 IU/kg/week) and high (> 500 IU/kg/week) doses of EPO and, within these subgroups, analyses of the use of low (< 5 mg/kg/day) and high (> 5 mg/kg/day) doses of supplemental iron, in reducing red blood cell transfusions in these infants.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE, EMBASE, CINAHL, abstracts from scientific meetings published in Pediatric Research and reference lists of identified trials and reviews were searched in November 2005. No language restrictions were applied.

SELECTION CRITERIA

Randomised or quasi-randomized controlled trials of early initiation of EPO treatment (started before 8 days of age) vs. placebo or no intervention in preterm (< 37 weeks) and/or low birth weight (< 2500 g) neonates. For inclusion, the studies needed to provide information on at least one outcome of interest.

DATA COLLECTION AND ANALYSIS

Data were abstracted by the two authors on pre-tested data collection forms. Data were entered by one review author (AO) and checked for accuracy by the other (SA). Data were analysed using RevMan 4.2.8. The statistical methods included 'typical' relative risk (RR), risk difference (RD), number needed to treat to benefit (NNTB) and needed to treat to harm (NNTH) for dichotomous outcomes and weighted mean difference (WMD) for continuous outcomes reported with their 95% confidence intervals (CI). A fixed effects model was used for meta-analyses. Heterogeneity tests, including the I(-)squared (I(2)) statistic, were performed to assess the appropriateness of pooling the data.

MAIN RESULTS

Twenty-three studies enrolling 2074 preterm infants in 18 countries were included in the review. All studies except one applied transfusion guidelines. The quality of the trials varied. Most trials were of small sample size. Only one study clearly stated that infants were excluded if they had received red blood cell transfusion prior to study entry (Arif 2005). A total of 16 studies, including 1825 infants reported on the primary outcome of "use of one or more red cell transfusions". The summary estimates were significant [typical RR; 0.80 (95% CI 0.75, 0.86); typical RD; -0.13 (95% CI -0.17, -0.09); typical NNTB; 8 (95% CI 6, 11)]. There was statistically significant heterogeneity [for RR (p< 0.004), I(2) = 56.7%; for RD (p = 0.003), I(2 ) = 56.0%]. Similar results were obtained in secondary analyses based on different combinations of high doses of EPO and high and low iron supplementation. There were insufficient data to draw conclusions for low doses EPO in combination with high or low dose of iron. Two studies (n = 188) reported a significant reduction in the number of donors to whom the infant was exposed [typical WMD; -0.63 (95% CI -1.07, -0.19)]. A significant reduction in the total volume (ml/kg) of blood transfused per infant [typical WMD; -6 ml (95% CI -1, -11)] and in the number of transfusions per infant [typical WMD -0.27 (95% CI -0.12, -0.42 )] was noted. There was a significant increase in the risk of stage > 3 retinopathy of prematurity (ROP) in the EPO group [typical RR; 1.71 (95% CI 1.15, 2.54); typical RD; 0.05 (95% CI 0.01, 0.09); NNTH; 20 (95% CI 11, 100)]. The non-significant results for ROP (any stage reported) showed a similar trend. The increased risk for ROP may be associated with use of higher doses of supplemental of iron in the EPO group than in the control group. The rates for mortality, sepsis, intraventricular haemorrhage, periventricular leukomalacia, necrotizing enterocolitis, bronchopulmonary dysplasia, neutropenia, hypertension, length of hospital stay or long-term neurodevelopmental outcomes were not significantly change by the administration of EPO.

AUTHORS' CONCLUSIONS

Early administration of EPO reduces the use one or more red blood cell transfusions, the volume of red blood cells transfused, and the number of donors and transfusions the infant is exposed to following study entry. The small reductions are of limited clinical importance. Any donor exposure is likely not avoided as most studies included infants, who had received red cell transfusions prior to trial entry. There was a significant increase in the rate of ROP (stage >3). Animal data and observational studies in humans support a possible association between treatment with EPO and the development of ROP. EPO does not significantly decrease or increase any of the other important neonatal adverse outcomes including mortality. The incidence of ROP should be ascertained in the studies that have already been conducted but did not report on this outcome. Any ongoing research should deal with the issue of ROP and evaluate the current clinical practice that will limit donor exposure through satellite units. Research efforts should focus on limiting donor exposure (to as few donors as possible) during the first few days of life in sick neonates, when red blood cell transfusions are most likely to be required and cannot be prevented by early (or late) EPO treatment. Due to the limited benefits and the increased risk of ROP, early administration of EPO is not recommended.

Erythropoietin: an update on the therapeutic use in newborn infants and children

Recombinant human erythropoietin (epoetin) has become the most widely used cytokine in the world. Following the success of its use in patients with end-stage renal disease, the usefulness of epoetin in other anaemias was assessed, including paediatric patients, mainly newborns. The treatment or prevention of anaemia of prematurity with epoetin resulted in a significant reduction in the number of transfusions and donor exposure. A clear definition of which premature babies must receive therapy is yet to be established. Other indications in neonatal period include hyporegenerative and haemolytic anaemias. The potential for use of the nonhaematopoietic effects of epoetin in newborn infants is a novel and exciting issue. The role of epoetin as a tissue-protective factor for the CNS and intestinal mucosa is under exhaustive investigation. With the exception of chronic renal failure, in older children the efficacy of epoetin has not been evaluated as in adults. Although an impressive amount of studies were carried out during recent years in adult patients with cancer-related or HIV-infection-related anaemias, thus allowing clear conclusions to be established on its efficacy, only a few trials with a small number of patients have been reported in children. Up-to-date, results in paediatric patients suggest that epoetin therapy is as useful as in adult patients, but prospective, randomised trials including large number of patients are essential to achieve definitive conclusions.

Stepping up versus standard doses of erythropoietin in preterm infants: a randomized controlled trial

In this study, it is hypothesized that a planned increase in the dose of recombinant human erythropoietin (rh-EPO) can prevent transfusion in very low birth weight infants. Two different regimens of rh-EPO were administrated, one consisting in increasing dosage up to 5000 U/kg/wk, according to the individual reticulocytes response, and the second in a standard therapy of 1250 U/kg/wk. Fifty-one infants participated. Despite a significant higher reticulocytosis, the study was prematurely terminated due to the results of an interim analysis showing that transfusion was not avoided by increasing the rh-EPO. No significant differences were found between the two regimens concerning transfusion rate, volume transfused, gain in weight, and adverse effects. Progressive titration of rh-EPO to improve the biological response does not leave premature infants free of transfusion.

Erythropoietin and prematurity--where do we stand?

Erythropoietin (EPO) treatment for anemia of prematurity is still controversial. Large multicentric trials demonstrate that administration of EPO+Fe cannot prevent early transfusions, particularly in very low birth weight newborns and in infants with severe neonatal diseases, but may have some beneficial effect to prevent late transfusions. Current treatment of anemia of prematurity should be multifactorial trying to minimize all causes that reduce erthrocytic mass (phlebotomies, use of noninvasive procedures) and promoting all factors that increase it (placental transfusion, adequate nutrition support). To evaluate the real impact of EPO treatment it is mandatory to follow similar transfusion protocols for preterm infants in all the studies. The aim of EPO+Fe administration should be to avoid new late transfusions in very low birth weight preterm infants or to prevent the first transfusion after the second week of life in less immature premature with the objective of reducing the number of donors rather than the number of transfusions. We have limited the use of EPO+Fe to infants <30 weeks gestational age and birth weight <or=1250 g as well as to infants weighing 1250-1500 g with initial severe disease. The comparison of outcomes before (28 months period with EPO+Fe treatment to all premature <or=32 weeks gestational age) and after 20 months of implementation of the new protocol showed a significant decrease in EPO+Fe treatment candidates (40.3% vs. 85.9%, P<0.001) without changes in the percentage of transfusions in both periods. Therefore if EPO treatment is to be given it should be limited to preterm infants with a birth weight <1000 g or those of 1000-1250 g associated with risk factors for blood transfusion. It should be started at 3-7 days of life at doses of 250 U/kg subcutaneously, three times a week, for 4-6 weeks depending on gestational age with oral iron 2-12 mg/kg/day to keep ferritin levels greater than 100 ng/mL.

Single-dose darbepoetin administration to anemic preterm neonates

OBJECTIVE

Darbepoetin is longer acting and more potent than recombinant erythropoietin (rEpo). In certain situations, preterm neonates might benefit from rEpo, and for such patients darbepoetin would require fewer doses at a lower cost. However, the proper dose and dosing interval have not been established.

STUDY DESIGN

We performed a prospective trial in two level III Neonatal Intensive Care Units. Patients <32 weeks gestation at birth, with a birth weight (BW) <1500 g, were eligible for participation if they were >21-days-old and had a hemoglobin (Hgb) concentration </or=10.5 g/dl. In all, 12 were to receive a single subcutaneous (s.c.) dose at either 1 or 4 microg/kg. Once before the dose was given, and at two preset intervals after, blood was obtained for immature reticulocyte fraction (IRF) and absolute reticulocyte count (ARC). Once before and at four preset intervals after, blood was obtained for pharmacokinetic studies.

RESULTS

The 12 subjects had BWs of 1129+/-245 g (mean+/-SD), were 29.2+/-1.2 weeks gestation at delivery, and were 43+/-12 days old with an Hgb concentration of 9.6+/-1.0 g/dl when the darbepoetin was given. Six received 1 microg/kg and six 4 microg/kg. The IRF increased (p<0.05) as did the ARC (p<0.05). The increases in IRF were somewhat greater among the 4 microg/kg recipients (P=0.06). The highest recorded concentrations of drug occurred 6 to 12 hours after administration. The combined 6 and 12 hours values were 185+/-106 mU/ml in the 1 microg/kg group vs 597+/-238 in the 4 microg/kg group (p<0.002). The t(1/2) was 26 hours (range 10 to 50). The biovailability-normalized clearance was 19 ml/hour/kg (range 5 to 54).

CONCLUSIONS

A single s.c. dose of darbepoetin given to preterm neonates accelerated effective erythropoiesis. The pharmacodynamic and pharmacokinetic findings suggest that darbepoetin dosing in neonates would require a higher unit dose/kg and a shorter dosing interval than are generally used for anemic adults.

Methylprednisolone sodium succinate in pediatric parenteral nutrition: influence of vehicle injection

Many drugs can be administered in parenteral nutrient mixtures, but no work on the delivery of corticoids by such means is reported. We studied the influence of pediatric parenteral nutrient mixtures on the kinetic parameters of the corticoid methylprednisolone injected in an intravenous bolus in rabbits as its sodium succinate ester. Four groups of six male New Zealand rabbits were used. After extraction, the plasma drug concentrations were measured by high performance liquid chromatography. The distribution volume of the ester and the clearance rates of the two entities (ester and methylprednisolone) were lowered in the presence of a lipid emulsion. The description of these pharmacokinetic parameters provides a basis for a preclinical study of 24h administration of methylprednisolone in a parenteral nutrient mixture.

Érythropoïétine chez le nouveau-né : efficacité comparée des voies d’administration sous-cutanée et intraveineuse

OBJECTIVE

Our aim was to compare the effectiveness of a one-month treatment with recombinant human erythropoietine (rHuEpo) according to the administration route.

METHODS

Retrospective study based on the data collection from medical files of 64 preterm infant hospitalized in the "institut de puériculture et de périnatalogie" (Paris) between January 13th, 2002 and April 13th, 2002. The first group (N =33) was treated by subcutaneous rHuEpo 750 IU/kg per week, in three injections by week, for one month. The second group (N =15) was treated by continuous infusion of rHuEpo in total parenteral nutrition 1050 IU/kg per week (30% augmentation to compensate the amount absorbed by the filter). The third group (N =16) received 750 IU/kg per week of rHuEpo in three direct intravenous injections. The effectiveness of rHuEpo was evaluated by the absolute reticulocyte count, the level of hemoglobin and the incidence of blood transfusion (multiple logistic analysis of variant and regression).

RESULTS

The absolute reticulocyte count and hemoglobin level were significantly reduced after one month of treatment by continuous infusion of rHuEpo in total parenteral nutrition and direct intravenous injections compared with a one-month treatment by subcutaneous rHuEpo. Hemoglobine level were at 8.8 and 9.6 g/dl vs 10.3 g/dl (P =0.02) and absolute reticulocyte count at 123,000/mm3 and 190,000/mm3 vs 216,000/mm3 (p =0.001). The number of transfused infants was significantly increased with utilization of continuous (40%) and direct intravenous (75%) compared with those treated by subcutaneous route (21.2%) while the ferritin level and phlebotomy losses were not significantly different in the three groups. The number of blood transfusion was significantly linked to phlebotomy losses and administration route of rHuEpo.

CONCLUSION

Our study tends to demonstrate that rHuEpo administered subcutaneously reduces significantly the number of transfusion in contrary to intravenous routes. Waiting for pilot study and new molecules, we recommend subcutaneous administration of rHuEpo to preterm infants 250 IU/kg three times weekly in the treatment of anemia of prematurity.

Long-acting erythropoietin: clinical studies and potential uses in neonates

Aranesp (darbepoietin alfa) is a biologically modified form of recombinant human erythropoietin (rHuEpo). Two additional carbohydrate-binding sites give Aranesp a half-life about three times that of rHuEpo. Extensive studies in adults and early studies in children indicate that Aranesp can be administered far less frequently than rHuEpo with an equivalent erythropoietic effect. This article reviews these studies and reports on the in vitro effects of Aranesp on human fetal and neonatal erythroid progenitors.

Enterally dosed recombinant human erythropoietin does not stimulate erythropoiesis in neonates

OBJECTIVES

Human fetuses and neonates ingest erythropoietin (Epo) when they swallow amniotic fluid, colostrum, and human milk. This study was designed to determine whether enterally dosed recombinant Epo (rEpo) stimulates erythropoiesis in preterm neonates.

METHODS

Preterm infants (<1500 g birth weight) were randomly assigned to receive feedings supplemented with either rEpo (1000 U/kg per day) or placebo for 14 days (n=36). Reticulocyte counts, serum Epo concentrations, hematocrit, and zinc protoporphyrin to heme ratios were measured at baseline and after 7 and 14 days of study drug administration. Transfusion guidelines were followed. Transfusion requirements, medications, feeding tolerance, and clinical diagnoses were documented.

RESULTS

Enteral rEpo was well tolerated. There were no differences in erythropoietic indexes based on treatment group. Serum Epo concentrations were not different in the treatment versus placebo group, nor were transfusion requirements.

CONCLUSIONS

Enterally dosed rEpo (1000 U/kg/day) does not significantly influence erythropoiesis or iron utilization when given for a 2-week period, nor does it elevate the serum Epo concentration in preterm or term infants. Oral administration of rEpo is not an effective substitute for parenteral administration.

[Recombinant human erythropoietin: analysis of a policy of treatment in an hospital based population of very-low-birthweight infants]

AIM OF THE STUDY

To evaluate a policy of treatment with human recombinant erythropoietin (rhEPO) and to describe factors related to red blood cell transfusions (RBCTs) in treated neonates.

STUDY

Prospective, observative study.

PATIENTS AND METHODS

One-hundred and sixty-five neonates with gestational age (GA) < 30 weeks and/or birthweight < 1000g admitted between may 1998 and october 1999. Ninety were excluded (congenital malformations n = 6, deaths n = 16, referral to a general hospital before discharge n = 67, ECMO n = 1). Data about the characteristics of the population, the severity of the neonatal period, hemoglobin at birth, blood loses, treatment with rhEPO, number of red blood cells transfusions (RBCTs) and donors were recorded in all infants.

RESULTS

Thirty-eight in seventy-five (51%) neonates received 112 blood transfusions. Eighty-eight were prescribed after day 15. In most of the cases (n = 68), RBCTs were done according to the protocol. In 20 cases (23%) infants were transfused during a late-onset infection. No difference was observed between the non-transfused (group I) and the transfused neonates (group II) with regards to the drug administration: first dose on day 3 +/- 2, number of injections (17 +/- 4 vs 18 +/- 1, ns). The start of oral supplementation with iron was late (12j +/- 8 vs 19j +/- 10, ns). Infants in group II had a lower birthweight (850 +/- 240 vs 1050 +/- 160 g, p < 0,01) for a similar GA (28 +/- 1SA vs 28 +/- 2SA, ns) in association with an increased number of small for date babies (p = 0.03). Antenatal steroïds administration (89 vs 74%, ns), administration of surfactant (59 vs 81%, ns) were similar in the two groups. The Clinical Risk Index for Babies was higher in group II: 5 +/- 3 vs 2 +/- 1 (p < 0,001) as was the duration of oxygen delivery (53 +/- 44 vs 14 +/- 20 days, p < 0,01) and postnatal administration of corticosteroïds ( 38% vs 3%, p < 0.01).

CONCLUSION

The quality of iron administration, RBCTs and the limitation of donors could be improved in our population. Transfusions among neonates born before 30 weeks and/or with a birthweight of less than 1000 g and treated with rhEPO are associated with intrauterine malnutrition and a worse clinical condition on admission. Early identification of at risk neonates could improve prevention of RBCTs and the efficacy of rhEPO administration to preterm infants.

Absorption of enteral recombinant human erythropoietin by neonates

BACKGROUND

Erythropoietin (EPO) is present in amniotic fluid, colostrum, and human milk. One possible function of ingested EPO might be to stimulate erythropoiesis. However, it is unclear whether human neonates absorb recombinant human erythropoietin (rhEPO) after oral administration.

OBJECTIVE

To determine whether circulating EPO concentrations increase following enteral administration of rhEPO to neonates.

METHODS

The study was designed as a 2-center prospective, blinded, randomized, 2 x 2 crossover study, with each infant receiving 1 dose of rhEPO 1000 units/kg and 1 dose of placebo. Serum EPO concentrations were measured at baseline, 2, and 4 hours following study drug administration. The rhEPO and placebo dosing were separated by a mean of 72 hours. Analysis was stratified by gestational age (< or =35 wk, >35 wk) and feeding type (human milk, infant formula).

RESULTS

No significant change in serum EPO concentration was identified at 2 or 4 hours following enteral administration of rhEPO.

CONCLUSIONS

Enteral administration of a large dose of rhEPO to neonates <4 months of age did not result in increased circulating EPO concentrations at 2 or 4 hours following dosing, regardless of whether it was administered in human milk or infant formula.

Human recombinant erythropoietin in the prevention and treatment of anemia of prematurity

Human recombinant erythropoietin has been studied extensively as treatment for a variety of anemias. Since in vitro studies showed the primary etiology of the anemia of prematurity to be insufficient serum erythropoietin concentrations, clinical trials have evaluated the administration of human recombinant erythropoietin to preterm infants to treat this indication. These studies were followed by pharmacokinetic determinations in animal models and preterm infants, which revealed that preterm infants required greater doses of human recombinant erythropoietin because of a more rapid clearance and greater volume of distribution. Recent studies have focused on the administration of human recombinant erythropoietin in the first weeks of life to alleviate the anemia caused by excessive phlebotomy losses, and to prevent the anemia of prematurity. In addition, human recombinant erythropoietin has been tried clinically in a variety of neonatal populations in an attempt to decrease or eliminate transfusions. Although much information has been accumulated about the clinical use of human recombinant erythropoietin in preterm infants over the last 15 years, many questions remain unanswered. The evolution of clinical practice in the care of extremely low birthweight infants continues to affect the number of transfusions. It is likely that human recombinant erythropoietin administration in combination with instituting rigorous transfusion guidelines and decreasing phlebotomy losses will have the greatest impact in decreasing transfusion requirements in all preterm and term neonates, regardless of the etiology of their anemia.

Iron status and the treatment of the anemia of prematurity

Many unanswered issues regarding rhEPO therapy in prematurity remain, including which premature infants best respond to rhEPO, what the long-term effect of decreased erythrocyte transfusions is, how nutritional supplementation optimizes the effect of rhEPO, whether or not rhEpo therapy causes iron deficiency later in life, and whether or not it is safe to supplement with parenteral iron. Further study of rhEPO therapy and iron status in prematurity is necessary.

Reticulocyte analysis by flow cytometry and other techniques

Enumeration of peripheral blood reticulocytes is an essential part of the diagnosis and management of anemic patients, since the number of reticulocytes in the peripheral blood reflects the erythrocytic activity of the bone marrow. Reticulocyte enumeration using flow cytometric methodology is rapidly replacing the inaccurate, imprecise manual counting technique used in the past. This article explores the pathophysiology of the reticulocyte, the various means of counting reticulocytes, and the diverse clinical applications of reticulocyte data.

Effects of early erythropoietin therapy on the transfusion requirements of preterm infants below 1250 grams birth weight: a multicenter, randomized, controlled trial

OBJECTIVES

Infants of </=1250 g birth weight receive multiple erythrocyte transfusions during their hospitalization. We hypothesized that early erythropoietin (Epo) and iron therapy would 1) decrease the number of transfusions received (infants 401-1000 g birth weight; trial 1) and 2) decrease the percentage of infants who received any transfusions (1001-1250 g birth weight; trial 2).

METHODS

A total of 172 infants in trial 1 and 118 infants in trial 2 were randomized to treatment (Epo, 400 U/kg 3 times weekly) or placebo/control. Therapy was initiated by 4 days after birth and continued through the 35th postmenstrual week. All infants received supplemental parenteral and enteral iron. Complete blood and reticulocyte counts were measured weekly, and ferritin concentrations were measured monthly. Transfusions were administered according to protocol. Phlebotomy losses and transfusion data were recorded.

RESULTS

Treated and placebo/control infants in trial 1 received a similar number of transfusions (4.3 +/- 3.6 vs 5.2 +/- 4.2, respectively). A similar percentage of treated and control infants in trial 2 received at least 1 transfusion (37% vs 46%). Reticulocyte counts were higher in treated infants during each week of the study in both trials. Hematocrits were higher among treated infants from week 2 on in both trials. Ferritin concentrations were higher in placebo/controls than in treated infants at weeks 4 and 8 in trial 1 and at week 4 in trial 2. No adverse effects of Epo or supplemental iron occurred.

CONCLUSION

The combination of early Epo and iron as administered in this study stimulated erythropoiesis in infants who were </=1250 g at birth. However, the lack of impact on transfusion requirements fails to support routine use of early Epo.neonate, intravenous iron, donor exposure.

Enteral absorption of erythropoietin in the suckling rat

Milk contains biologically relevant concentrations of erythropoietin (Epo), the primary hormone responsible for erythrocyte production. In animals, milk-borne Epo stimulates erythropoiesis. Epo receptors have been found in nonerythropoietic tissues including gastrointestinal tract. We hypothesized that milk-borne Epo is distributed to local gastrointestinal tissues, absorbed intact, and then distributed peripherally via the systemic circulation. Rat milk protected recombinant human Epo (rhEpo) from degradation in the suckling rat gastrointestinal tract. Simulated digestion of (125)I-rhEpo in suckling rat gastrointestinal juices was performed. When measured by acid precipitation and immunoassay, rat milk protected rhEpo from gastrointestinal juices better than saline (p < 0.0001). The fate of enterally administered milk-borne (125)I-rhEpo was examined in 10-d-old rats. RhEpo fed in rat milk was better protected from in vivo proteolytic degradation than rhEpo in saline (p < 0.05). After enteral (125)I-rhEpo dosing, radiolabeled protein from gastric tissue comigrated on SDS-PAGE with intact rhEpo at 36.5 kD. To determine the local and systemic distribution of physiologic intakes of rhEpo, suckling rats were fed (125)I-rhEpo in rat milk, and tissues were harvested 1, 2, and 4 h later. Intact (125)I-rhEpo was found in gastric and small intestinal walls and lumens. Five percent of total administered dose was found intact in the plasma, whereas another 8 to 10% of total administered dose was localized to bone marrow, percentages comparable to those seen after parenteral administration. Radiolabel was also localized to liver and peripheral solid tissues. These patterns of localization and degradation of rhEpo after acute administration support both systemic absorption and gastrointestinal cellular processing.

Receptor-based model accounts for phlebotomy-induced changes in erythropoietin pharmacokinetics

Previous clinical studies have demonstrated two distinctive pharmacokinetic behaviors of erythropoietin (EPO): changes in pharmacokinetics (PK) after a period of rhEPO treatment and nonlinear pharmacokinetics. The objective of this work was to study the temporal changes in EPO's PK following phlebotomy in order to propose possible mechanisms for this behavior. Five healthy adult sheep were phlebotomized on two separate occasions 4-6 weeks apart to hemoglobin levels of PK 3-4 g/dL. PK parameters were estimated from the concentration-time profiles obtained following repeated intravenous bolus PK studies using tracer doses of biologically active 125I-rhEPO. Based on the changes in clearances, a PK model was derived to provide a mechanistic receptor-based description of the observed phenomena. Phlebotomy resulted in a rapid increase in the EPO plasma concentration, which peaked at 760 +/- 430 mU/mL (mean +/- SD) at 1.8 +/- 0.65 days, and which coincided with a transient reduction in EPO clearance from prephlebotomy values, i.e., from 45.6 +/- 11.2 mL/hr/kg to 24.3 +/- 9.7 mL/hr/kg. As plasma EPO levels returned toward baseline levels in the next few days, a subsequent increase in EPO clearance was noted. EPO clearance peaked at 90.2 +/- 26.2 mL/hr/kg at 8.5 +/- 3.3 days and returned to baseline by 4-5 weeks postphlebotomy. The proposed model derived from these data includes positive feedback control of the EPO receptor (EPOR) pool. The model predicts that: 1) the initial reduction in EPO plasma clearance is due to a transient saturation of EPORs resulting from the phlebotomy-induced high EPO concentration; and 2) the EPOR pool is expandable not only to compensate for EPOR loss but also to adjust to a greater need for EPORs/progenitor cells to restore hemoglobin (Hb) concentration to normal levels.

Effect of intravenous iron supplementation on erythropoiesis in erythropoietin-treated premature infants

OBJECTIVE

To test the efficacy and safety of combining intravenous iron in amounts approximating the in utero iron accretion rate and the postnatal iron loss with erythropoietin (EPO) in very low birth weight (VLBW) infants.

METHODS

A prospective, controlled, randomized, unmasked trial lasting 21 days was performed in 29 clinically stable VLBW infants <31 weeks' gestation and <1300 g birth weight not treated with red blood cell transfusions during the study period. Mean (+/- standard error of the mean) age at study entry was 23 +/- 2.9 days. After a 3-day run-in baseline period in which all participants received oral supplements of 9 mg/kg/day of iron polymaltose complex (IPC), participants were randomized to receive 18 days of treatment with: 1) oral IPC alone (oral iron group); 2) 300 U of recombinant human EPO (r-HuEPO) kg/day and daily oral IPC (EPO + oral iron group); 3) 2 mg/kg/day of intravenous iron sucrose, r-HuEPO, and oral iron (intravenous iron + EPO group). To assess efficacy of the 3 treatments, serial blood samples were analyzed for hemoglobin (Hb), hematocrit (Hct), reticulocyte count, red blood cell indices and plasma levels of transferrin, transferrin receptor (TfR), ferritin, and iron. Oxidant injury was assessed before and after treatment by plasma and urine levels of malondialdehyde (MDA) and o-tyrosine.

RESULTS

At the end of treatment, Hb, Hct, reticulocyte count, and plasma TfR were markedly higher in both of the EPO-treated groups, compared with the oral iron group. At study exit a trend toward increasing Hb and Hct levels and significantly higher reticulocyte counts were observed in the intravenous iron + EPO group, compared with the EPO + oral iron group. During treatment, plasma ferritin levels increased significantly in the intravenous iron + EPO group and decreased significantly in the other 2 groups. By the end of treatment, ferritin levels were significantly higher in the intravenous iron + EPO group compared with the other 2 groups. Although plasma and urine MDA or o-tyrosine did not differ among the 3 groups, plasma MDA was significantly greater in the subgroup of intravenous iron + EPO participants sampled at the end of the 2-hour parenteral iron infusion, compared with values observed immediately before and after parenteral iron-dosing.

CONCLUSIONS

In stable VLBW infants receiving EPO treatment, parenteral supplementation with 2 mg/kg/day of iron sucrose results in a small, but significant, augmentation of erythropoiesis beyond that of r-HuEPO and enteral iron alone. However, to reduce the potential adverse effects of parenteral iron/kg/day on increasing plasma ferritin levels and on causing oxidative injury, we suggest that the parenteral iron dose used should be reduced and/or the time of infusion extended to maintain a serum iron concentration below the total iron-binding capacity.

The use of erythropoietin in neonates

Although much information has been accumulated about the clinical use of Epo in preterm infants, many questions remain unanswered. The evolution of clinical practice in the care of extremely ill, preterm infants continues to affect the number of transfusions required during hospitalization. Decreasing phlebotomy losses and instituting standardized transfusion guidelines have both been shown significantly to decrease the transfusion requirements of preterm infants. The administration of Epo likely decreases transfusion need even further; however, the direct impact of each of these actions has not been studied prospectively. It is likely that the combination of instituting rigorous and standardized transfusion guidelines, decreasing phlebotomy losses, and the appropriate use of Epo will have the greatest impact in decreasing transfusion requirements in all preterm and term neonates, regardless of the cause of their anemia.

Effect of early versus late administration of human recombinant erythropoietin on transfusion requirements in premature infants: results of a randomized, placebo-controlled, multicenter trial

OBJECTIVE

The administration of recombinant human erythropoietin (rHuEPO), started after the first 2 weeks of life, reduces the transfusion requirement in premature infants. However, its use throughout the first 2 weeks of life, when anemia results predominantly from phlebotomy losses, remains controversial. We investigated whether early use of rHuEPO would reduce the total transfusion requirement and/or the number of transfusions throughout the first 2 weeks of life.

METHODS

We randomized 114 infants with birth weight (BW) <1250 g to receive rHuEPO (1250 units/kg/week; IV; early group: n = 57) or placebo (late group: n = 57) from day 2 to day 14 of life; subsequently, all the patients received rHuEPO (750 units/kg/week, subcutaneously) for 6 additional weeks. All infants were given oral iron (6 mg/kg/day) and folic acid (2 mg/day).

RESULTS

The early group showed higher hematocrit and reticulocyte counts than the late group in the first 3 weeks of life, but there was no difference in the total number of transfusions (early: 1.8 +/- 2.3 vs late: 1.8 +/- 2.5 transfusion/patient) or the transfusion requirement throughout the first 2 weeks of life (early:.8 +/- 1.1 vs late:.9 +/- 1.3) could be demonstrated. In infants with BW <800 g and total phlebotomy losses >30 mL/kg (n = 29), a lower number of transfusions was received by infants in the early group, compared with late group, from the second week to the end of the treatment (early: 3.4 +/- 1.1 vs late: 5.4 +/- 3.7 transfusion/patient). No clinical adverse effects were observed. Thrombocytosis was detected during the treatment with rHuEPO in 31% of the infants.

CONCLUSIONS

In the whole population, the early administration of rHuEPO induced a rise of reticulocyte counts, but not enough to reduce the transfusion requirement. The most severely ill infants (BW <800 g and phlebotomy losses >30 mL/kg) seemed to benefit from early use of rHuEPO, and this deserves additional study.

Factors associated with successful epoetin alfa therapy in premature infants

OBJECTIVE

To determine the impact of two different recombinant human erythropoietin (epoetin alfa) dosing strategies on the number of red blood cell (RBC) transfusions, and explore relationships between specific patient and drug regimen variables with epoetin alfa therapy outcomes.

DESIGN

Retrospective cohort study.

SETTING

Level III university neonatal intensive care unit.

METHODS

Infants who received epoetin alfa therapy three times weekly for more than one week were categorized into two epoetin alfa dosing strategy groups: group A (300-749 units/kg/wk) and group B (750-1200 units/kg/wk). The following patient variables were collected and their relationship to therapy outcomes (corrected reticulocyte count [%], hematocrit [%], and number of RBC transfusions after therapy was started) were evaluated using independent Student's t-test, correlation analysis, and stepwise linear regression: birth weight (kg), gestational age (weeks), postnatal age at therapy onset (days), duration of mechanical ventilation (days), number of RBC transfusions before epoetin alfa therapy, phlebotomy loss (mL/kg), epoetin alfa dosage (units/kg/dose), iron dosage (mg/kg/d), duration of therapy (days), and postconceptional age at therapy discontinuation (weeks).

RESULTS

The charts of 44 patients were reviewed. No significant impact on outcome was attributed to overall dosing strategy (group A vs. group B). Linear regression identified postnatal age at therapy onset as a significant contributor to mean hematocrit (R2 = 2 0.116; p = 0.023) and postconceptional age at therapy discontinuation as a significant contributor to number of transfusions during and after epoetin alfa use (R2 = 0.118; p = 0.022). A significant positive correlation was found between weekly mean epoetin alfa dosage and mean reticulocyte count (r = 0.326; p = 0.046), mean iron dosage and mean reticulocyte count (r = 0.439; p = 0.006), and ventilator days and total number of transfusions (r = 0.606; p < 0.001). A significant negative correlation was found between number of transfusions and reticulocyte count (r = -0.367; p = 0.023).

CONCLUSIONS

Epoetin alfa dosing strategy, as defined in our study, did not significantly affect the number of transfusions. However, postnatal age at therapy initiation, postconceptional age at therapy discontinuation, mean epoetin alfa dosage, and iron dosage correlate with specific outcomes of epoetin alfa therapy in premature infants.

Erythropoietin and the incidence of necrotizing enterocolitis in infants with very low birth weight

BACKGROUND/PURPOSE

The presence of erythropoietin (Epo) in human milk and the expression of Epo receptors on intestinal villous enterocytes of neonates suggest that Epo has a role in growth and development of the gastrointestinal tract. On this basis, the authors hypothesized that recombinant Epo (rEpo) given for prevention or treatment of the anemia of prematurity would protect against necrotizing enterocolitis (NEC).

METHODS

A retrospective cohort study was conducted from a university neonatal intensive care unit of 483 very low birth weight (500 to 1,250 g) neonates born from July 1, 1993 to January 1, 1998.

RESULTS

A total of 260 neonates received rEpo, and 223 did not (control group). The rEpo and control groups were similar in gender distribution (52% v. 48% boys), gestational age (26.8+/-2.1 v. 27.6+/-2.9 weeks; mean +/- SD), birth weight (895+/-198 v. 911+/-208 g), 1 and 5 minute Apgar scores (4.2 and 6.1 v4.7 and 6.7), and incidence of severe intraventricular hemorrhage (8.9% v. 10.3%). The rEpo group had a lower incidence of NEC (12 of 260, 4.6% v. 24 of 223, 10.8%; P = .028, 95% confidence interval for difference: -0.108 to -0.015).

CONCLUSION

In very low birth weight infants, the incidence of NEC is lower in those who received rEpo.

Blood banking issues pertaining to neonatal red blood cell transfusions

Many preterm infants are given multiple red blood cell transfusions during the early weeks of life. Because firm standards for neonatal transfusions do not exist, it is important to consider the pathophysiology of the anemia of prematurity, the goals of transfusion therapy and blood banking practices that best provide safe and effective neonatal transfusions. There is increasing agreement that efforts continue to minimize phlebotomy blood losses, to transfuse per conservative indications and to limit donor exposure by transfusing stored red blood cells from a single unit reserved for an infant--rather than insisting on fresh blood.

[Iron supplementation in preterm infants treated with erythropoietin]

Anemia in premature infants can be prevented by prophylactic treatment with recombinant human erythroprotein (r-huEPO). r-HuEPO as been used for a long time in patients with end-stage renal failure. The main factor which can limit r-HuEPO efficiency is limited iron bioavailability. Adapted iron supplementation is needed when preterm infants receive r-HuEPO in order to avoid the depletion of iron stores. Oral iron supplementation is simple but indigestibility is frequent. Furthermore, the intestinal absorption and utilization of oral iron is limited. Parenteral iron supplementation is possible in infants who are very pre-term as they are parenterally fed during the first weeks of life. There are various preparations of intravenous iron with different physicochemical properties. Toxicity and side-effects of parenteral iron preparations depend on these properties. Two parenteral iron preparations are available in France: iron-saccharate (Venofer) and iron-dextrin (Maltofer). Iron delivery and possible side-effects of these preparations are different and need to be considered before use in preterm infants.

Erythropoietin to prevent and treat the anemia of prematurity

Human recombinant erythropoietin was first cloned in 1985, and is currently available for clinical use for a variety of anemias. Following successful clinical trials using erythropoietin to treat adults with the anemia of end-stage renal disease, the first clinical trial evaluating the use of erythropoietin in preterm infants to treat anemia was published in 1990. Since that initial report, numerous clinical trials have reported various levels of success in the treatment of this anemia. Most recently, erythropoietin has been used in the first weeks of life in an attempt to prevent the anemia of prematurity. This review describes mechanisms of erythropoiesis in the fetus and neonate, and focuses on recent clinical trials evaluating the use of erythropoietin to prevent and treat anemia in preterm infants.

Iron supplementation enhances response to high doses of recombinant human erythropoietin in preterm infants

AIMS

To determine whether iron supplementation would enhance erythropoiesis in preterm infants treated with high doses of human recombinant erythropoietin (r-HuEPO).

METHODS

Sixty three preterm infants were randomly allocated at birth to one of three groups to receive: r-HuEPO alone, 1200 IU/kg/week (EPO); or r-HuEPO and iron, 1200 IU/kg/week of r-HuEPO plus 20 mg/kg/week of intravenous iron (EPO + iron); or to serve as controls. All three groups received blood transfusions according to uniform guidelines.

RESULTS

Infants in the EPO + iron group needed fewer transfusions than controls--mean (95% CI) 1.0 (0.28-1.18) vs 2.9 (1.84-3.88) and received lower volumes of blood--mean (95% CI) 16.7 (4.9-28.6) vs 44.4 (29.0-59.7) ml/kg. The EPO group also needed lower volumes of blood than the controls--mean (95% CI) 20.1 (6.2-34.2) vs 44.4 (29.0-59.7) ml/kg, but the same number of transfusions, 1.3 (0.54-2.06) vs 2.9 (1.84-3.88). Reticulocyte and haematocrit values from postnatal weeks 5 to 8 were higher in the EPO + iron than in the EPO group, and both groups had higher values than the controls. Mean (SEM) plasma ferritin was lower in the EPO group-65 (55) micrograms/l than in the EPO + iron group 780 (182) micrograms/l, and 561 (228) micrograms/l in the control infants.

CONCLUSIONS

Early administration of high doses of r-HuEPO with iron supplements significantly reduced the need for blood transfusion. Intravenous iron (20 mg/kg/week in conjunction with r-HuEPO yielded a higher reticulocyte count and haematocrit concentration after the forth week of life than r-HuEPO alone. Infants treated with r-HuEPO alone showed signs of reduced iron stores.

High-versus low-dose erythropoietin in extremely low birth weight infants. The European Multicenter rhEPO Study Group

OBJECTIVE

To investigate whether a weekly 1500 IU/kg dose of recombinant human erythropoietin (rhEPO) is more effective than a dose of 750 IU/kg/week in preventing anemia and reducing the transfusion need in infants with birth weights less than 1000 gm.

STUDY DESIGN

In a randomized, double-blind, multicenter trial, 184 infants with birth weights between 500 and 999 gm were treated with either rhEPO 750 (low-dose group) or 1500 IU/kg/week (high-dose group) from day 3 of life until 37 weeks' corrected age.

RESULTS

Thirty-two percent of the infants in each group did not receive any transfusion during the treatment period. The total volume of erythrocytes received was similar in each group. The success rate, defined as no transfusion needed and hematocrit value 0.30 L/L or greater, was 27.6% in the low-dose and 29.5% in the high-dose group (p = 0.96).

CONCLUSION

Doubling the rhEPO dose of 750 IU/kg/week is not indicated in infants with birth weights less than 1000 gm.