Controversies in selection of epoetin dosages. Issues and answers

Erythropoietin Suppresses the Hepatic Fibrosis Caused by Thioacetamide: Role of the PI3K/Akt and TLR4 Signaling Pathways

Erythropoietin (EPO) is recognized for its function in erythropoiesis; however, its potential antifibrotic effect against liver fibrosis remains unknown. This study examined whether EPO affects thioacetamide (TAA)-induced liver fibrosis by concentrating on the Toll-like receptor 4 (TLR4) cascade and the phosphatidylinositol 3-kinase (PI3K)/Akt pathway as possible pathways. Male Wistar rats were randomized into four groups, which included: the negative control group, the TAA group (intraperitoneal; TAA 100 mg/kg three times per week for 2 weeks), and EPO-treated groups (150 and 300 IU/kg, i.p.) for 2 weeks after TAA injections. EPO attenuated hepatic fibrosis in a dosage-dependent way, as manifested by the diminution in serum alanine aminotransferase and aspartate aminotransferase activities, as well as the increase in albumin level. EPO inhibited the increase in tissue levels of tumor necrosis factors-α, interleukin-1β, transforming growth factor-β1, and TLR4 and raised tissue levels of PI3K and p-PI3K. EPO antioxidant properties were demonstrated by restoring hepatic glutathione and superoxide dismutase by preventing the accumulation of hepatic malondialdehyde. Further, EPO increased the protein expression of PI3K and Akt and decreased TLR4 protein expression. Immunohistochemically, EPO treatment altered tissue histology and downregulated mitogen-activated protein kinase protein expression. Overall, the research suggested that EPO could prevent TAA-induced hepatic fibrosis through upregulating the PI3K/Akt signaling cascade and downregulation the TLR4 downstream axis.

Impact of erythropoietin on intensive care unit patients

Anemia is common in intensive care unit (ICU) patients. Red blood cell (RBC) transfusions are mainstays of their treatment and can be life-saving. Allogeneic blood components inherently bear risks of infection and immune reactions. Although these risks are rare in developed countries, recombinant human erythropoietin (rhEpo) and other erythropoiesis-stimulating agents (ESAs) have been considered alternative anti-anemia treatment options. As summarized herein, however, most of the clinical studies suggest that ESAs are not usually advisable in ICU patients unless approved indications exist (e.g., renal disease). First, ESAs act in a delayed way, inducing an increase in reticulocytes only after a lag of 3-4 days. Second, many critically ill patients present with ESA resistance as inflammatory mediators impair erythropoietic cell proliferation and iron availability. Third, the ESA doses used for treatment of ICU patients are very high. Fourth, ESAs are not legally approved for general use in ICU patients. Solely in distinct cases, such as Jehovah's Witnesses who refuse allogeneic blood transfusions due to religious beliefs, ESAs may be considered an exceptional therapy.

Physiology and pharmacology of erythropoietin

Human erythropoietin (Epo) is a 30.4 kDa glycoprotein hormone composed of a single 165 amino acid residues chain to which four glycans are attached. The kidneys are the primary sources of Epo, its synthesis is controlled by hypoxia-inducible transcription factors (HIFs). Epo is an essential factor for the viability and proliferation of erythrocytic progenitors. Whether Epo exerts cytoprotection outside the bone marrow still needs to be clarified. Epo deficiency is the primary cause of the anemia in chronic kidney disease (CKD). Treatment with recombinant human Epo (rhEpo, epoetin) can be beneficial not only in CKD but also for other indications, primarily anemia in cancer patients receiving chemotherapy. Considering unwanted events, the administration of rhEpo or its analogs may increase the incidence of thromboembolism. The expiry of the patents for the original epoetins has initiated the production of similar biological medicinal products ('biosimilars'). Furthermore, analogs (darbepoetin alfa, methoxy PEG-epoetin beta) with prolonged survival in circulation have been developed ('biobetter'). New erythropoiesis-stimulating agents are in clinical trials. These include compounds that augment erythropoiesis directly (e.g. Epo mimetic peptides or activin A binding protein) and chemicals that act indirectly by stimulating endogenous Epo synthesis (HIF stabilizers).

Effect of preprinted order form on epoetin alfa prescribing

PURPOSE

The effect of a required preprinted order form on the prescribing of epoetin alfa was evaluated.

SUMMARY

An initial drug-use evaluation (DUE) was conducted in January 2004 to determine how closely prescribing guidelines for epoetin alfa were being followed. A preprinted order form was then developed and approved by the medical staff, with use required for all adult epoetin alfa orders. A follow-up DUE was conducted in January 2006 to assess the effects of the preprinted order form on prescribing patterns. Expenditures for epoetin alfa for 12 months before and after implementation of the preprinted order form were also calculated. Data for 45 and 44 patients were reviewed for the initial and follow-up DUEs, respectively. Smaller doses were ordered at more frequent intervals and epoetin alfa was prescribed more often by nephrologists and less frequently by surgeons and critical care intensivists after implementation of the preprinted order form. Use of epoetin alfa according to hospital guidelines improved from 44% to 73% (p = 0.0089). Significantly more patients' ferritin and transferrin saturation values were measured postimplementation of the order form (p = 0.0176). In addition, the annual expense for epoetin alfa was reduced by $151,042, a 36% reduction from baseline.

CONCLUSION

Implementation of a required preprinted order form increased the frequency of appropriate prescribing of epoetin alfa in a community teaching hospital.

rHuEpo before high-dose therapy allows autologous peripheral stem-cell transplantation without red blood cell transfusion: a pilot study

To decrease red blood cell (RBC) transfusion requirements during high-dose therapy (HDT) for hematological malignancies, we conducted a pilot study to assess the effect of recombinant human erythropoietin (rHuEpo) given during chemotherapy before HDT and autologous peripheral stem-cell transplantation (APSCT). The transfusion histories of 15 HDT and APSCT for hematological disease performed in 11 consecutive patients who received rHuEpo (10 000 U subcutaneously three times/week) were compared to those of 22 HDT and ASCT performed in 17 consecutive historical controls matched for hematological parameters. rHuEpo increased the hemoglobin (Hb) level from 10.3+/-2.3 g/dl at diagnosis to 12.9+/-2.2 g/dl at the time of HDT in 11 patients; no major adverse effects occurred. Compared to historical controls (95%, 21/22), RBC transfusion requirements were significantly lower for rHuEpo recipients (26%, 4/15) (P=0.00001) and rHuEpo responders (15%, 2/13) (P=0.000002). After HDT and APSCT, fewer RBC transfusions were needed: 3.3, 1.2 and 0.3 RBC units for controls, rHuEpo recipients and rHuEpo responders, respectively (P=0.006 and 0.00002). Therefore, rHuEpo should be administered before, and not after HDT and APSCT, to lower RBC transfusion requirements after HDT and APSCT.

Anemia in heart failure: implications, management, and outcomes

Despite advances in the treatment of heart failure (HF) over the past decade, the prognosis remains poor. Anemia is a well-recognized comorbidity in many chronic conditions, but its role in HF has only recently been recognized. Anemia is significantly related to symptoms, exercise capacity, and prognosis in HF; it has been identified as an independent risk factor for mortality in those with left ventricular dysfunction. When HF patients have concomitant renal disease, they invariably become anemic owing to erythropoietin deficiency. In chronic HF patients without renal disease, erythropoietin levels may be elevated in response to anemia, but not adequately increased to overcome it. Some degree of erythropoietin resistance may also be present because of elevated plasma levels of cytokines. Several studies in anemic HF patients have shown positive outcomes using erythropoietin and iron supplementation therapy to increase hemoglobin concentrations to more normal levels. This article reviews the current information available regarding anemia in HF and discusses the clinical implications and treatment of this syndrome.

Recombinant human erythropoietin therapy in low-birthweight preterm infants: a prospective controlled study

BACKGROUND

This study aimed to detect the effectiveness of recombinant human erythropoietin therapy in preventing premature anemia in low-birthweight preterm infants.

METHODS

A total of 292 premature infants who were born earlier than 33 gestational weeks and smaller than 1500 g birthweight were enrolled into the study. In addition to their conventional supportive therapy (medications), recombinant human erythropoietin 200 U/kg twice a week, subcutaneously, was given to randomly selected 142 premature infants for 6 weeks. The blood count variables and need for transfusions were compared with the remaining 150 premature infants during 6 months follow up.

RESULTS

Serum erythropoietin levels were 11.3 +/- 6.1 mU/mL and 38.3 +/- 19.1 mU/mL in the erythropoietin group before and at the fourth week of the study, respectively (P < 0.001). Reticulocyte counts of the group treated with erythropoietin were 146 x 10(6) +/- 28 x 10(6)/mL and 122 x 10(6) +/- 27 x 10(6)/mL at the fourth and seventh week of the study, respectively, and these values were significantly higher when compared with the control group (P < 0.001 and P < 0.001). At the same period, hematocrit values were also found to be higher in the treatment group than the control group (P < 0.001). Serum ferritin levels were lower in the treatment group compared with the control group at the fourth week of the study. No side-effects related to erythropoietin usage were encountered. The need for packed cell transfusions were 47% in the group treated with erythropoietin and 62.6% in the control group. A statistically significant difference was found for transfusion needs between the control and treatment groups (P < 0.001).

CONCLUSION

Recombinant erythropoietin is effective therapy for maintaining stable hematocrit levels in low-birthweight preterm infants and prevents the need for blood transfusions.

Use of Epoetin Alfa in Critically III Patients

OBJECTIVE

To discuss the controversies regarding the use of epoetin alfa (EPO) for reducing red blood cell (RBC) transfusions in critically ill patients with anemia.

DATA SOURCES

A MEDLINE search (1966–July 2003) was conducted using the search terms anemia; critical illness; erythropoietin; epoetin alfa; and erythropoietin, recombinant. References of selected articles were reviewed for studies that may have been missed by the computerized search.

STUDY SELECTION AND DATA EXTRACTION

Studies pertaining to the use of EPO for anemia of critical illness with an emphasis on data obtained from controlled trials.

DATA SYNTHESIS

Anemia is a common complication in patients admitted to the intensive care unit (ICU). Two prospective, randomized studies have demonstrated decreased transfusion requirements associated with EPO administration in medical/surgical patients who were in the ICU for at least 3 days and had hematocrit concentrations <38%. No differences were found in length of stay or mortality. A multicenter trial found that a restrictive strategy of RBC transfusion (hemoglobin goal 7–9 g/dL) was associated with in-hospital mortality lower than that with a more liberal approach, which calls into question the 38% hematocrit goal in the EPO trials. Furthermore, preliminary results from an economic analysis of EPO use in the ICU setting have demonstrated that EPO is not cost-effective.

CONCLUSIONS

Given the controversies surrounding EPO administration in critically ill patients, institutions are encouraged to develop EPO guidelines to help ensure the most appropriate use of this expensive product. Additional studies regarding patients most likely to benefit from EPO therapy, the most effective dosing regimen, and use of adjunctive therapies are needed.

Erythropoietin-induced hypertensive urgency in a patient with chronic renal insufficiency: case report and review of the literature

Hypertension is a potentially dangerous side effect of erythropoietin treatment; however, extreme elevations in blood pressure are rare. A 75-year-old woman with chronic renal insufficiency was treated with subcutaneous erythropoietin. Three weeks before she started receiving erythropoietin, her hematocrit was 27.2%; after 5 weeks of treatment, it rose to 45.7%. The patient came to the emergency department and was admitted with hypertensive urgency. During her hospital stay she was treated with nitroglycerin and nitroprusside infusions, extended-release nifedipine, a variety of beta-blockers, clonidine, and furosemide. By day 3, her blood pressure was adequately controlled. Her renal insufficiency may have progressed as a result of the hypertensive episode, which probably was related to erythropoietin administration and the resultant rapid increase in her hematocrit. Erythropoietin dosing should be titrated to increase the hematocrit gradually, and blood pressure should be monitored closely to avoid serious side effects such as hypertensive emergencies.

Comparison between two and five doses a week of recombinant human erythropoietin for anemia of prematurity: a randomized trial

OBJECTIVE

To compare the erythropoietic response between two and five times a week dosages of recombinant human erythropoietin (r-EPO) using the same weekly dose, 500 U/kg, in very low birth weight (VLBW) infants.

STUDY DESIGN

Eighty VLBW infants were stratified into two gestational age groups and randomized to receive 500 U/kg of r-EPO either two or five times a week; 72 infants completed at least 4 weeks of study. The primary outcome variable was absolute reticulocyte counts at 4 weeks. Secondary outcome variables were hematocrits, transfusions, iatrogenic blood losses, infections, and serum ferritins. Multiple regression analysis was used to evaluate the secondary outcome variables.

RESULTS

By 4 weeks, absolute reticulocyte counts were higher in the infants given r-EPO five times a week [mean (SEM)]: 173 000/mm(3) (15 000) vs 220 000/mm(3) (18 000), two versus five doses per week, respectively. Hematocrits, 34.9% (0.9) vs 34.1% (0.8), and transfusions per infant, 2.06 (0.4) vs 2.11 (0.4), were not different between the groups. Additionally, 79% of the variance in the amount of blood transfused was accounted for by iatrogenic blood loss, the latter primarily associated with number of days ventilated. Episodes of sepsis and necrotizing enterocolitis were significantly associated with decreased absolute reticulocyte counts and increased transfusions.

CONCLUSIONS

More frequent dosing of the same weekly amount of r-EPO produced a significant and sustained increase in stimulated erythropoiesis in VLBW infants. The importance of this finding on reducing transfusions was not able to be demonstrated because this study was not intended to differentiate transfusions. In this population of infants and at the dose level of r-EPO, iatrogenic blood loss contributed more to transfusions than a lower level of erythropoiesis, the former primarily associated with mechanical ventilation. Based on this and other studies, when VLBW infants are at risk for greater phlebotomy losses, it may be justifiable to use more vigorous r-EPO treatment, and when at lower risk to use less frequent dosing to enhance cost-effectiveness.

Subcutaneous treatment with recombinant human erythropoietin--the influence of injection frequency and skin-fold thickness

Subcutaneous treatment with erythropoietin (epoetin) in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) is convenient, but the optimal injection frequency is under discussion. Epoetin was given subcutaneously to 22 stable anaemic CAPD patients in doses that adjust haemoglobin to 7.2+/-0.3 mmol/l during a correction period. During the maintenance period the frequency of injections in four randomized groups of patients was changed randomly to once, twice or three times a week or daily. Each period lasted more than 8 weeks. During the maintenance period the epoetin dose was almost unchanged, whether the patients were treated once, twice or thrice weekly. In 15 patients treated with daily injections, the overall dose reduction was 22%. These 15 patients were grouped arbitrarily into 7 patients with a skin-fold of more than 20 mm at the injection site, and 8 patients with a skin-fold of less than 20 mm at the injection site. The dose reduction correlated with skin-fold thickness; the reduction was seen only in the patients with skin-folds of less than 20 mm. Seven of the eight patients experienced an average dose reduction of 36+/-8%.

Use of Hematopoietic Growth Factors in the Neonatal Intensive Care Unit

Recombinant hematopoietic growth factors have emerged as valuable treatments for a variety of medical conditions. Recently, their applications have reached the neonatal intensive care unit, where they offer new therapeutic options for problems as common as anemia of prematurity, or as catastrophic as neonatal sepsis. When facing bacterial infection, it is known that newborn infants are capable of increasing their serum G-CSF concentrations. However, their response does not reach the concentrations that adults are able to achieve, and frequently neutropenia complicates the picture of neonatal sepsis. Although Phase III clinical trials are still in progress, published animal studies, case reports, and Phase I trials suggest that neonates with a variety of neutropenias experience a rapid elevation in their blood neutrophil concentration following administration of rG-CSF, without significant adverse effects. Although many factors contribute to the development of the “anemia of prematurity,” one of the major factors is the inability of preterm infants to generate an erythropoietin (Epo) response appropriate to their degree of anemia. On the basis of this fact, administration of rEpo to preterm neonates to treat or to prevent the anemia of prematurity has been the subject of multiple clinical studies, and it is now clear that rEpo administration to this population can indeed result in lower transfusion requirements, with only occasional and mild adverse effects. Neonatal thrombocytopenia is also a frequent clinical problem, which in most patients develops without a clear underlying cause. Recent studies, quantifying circulating megakaryocyte progenitors in the peripheral blood of thrombocytopenic neonates, suggest that impaired megakaryocytopoiesis may be the main underlying mechanism of many cases of thrombocytopenia. On the basis of this finding, it is tempting to speculate that recombinant thrombopoietin, the newly discovered physiological stimulator of platelet production, will be of clinical relevance in the treatment of thrombocytopenic neonates.