Saudi Journal of Kidney Diseases and Transplantation

ORIGINAL ARTICLE
Year
: 2006  |  Volume : 17  |  Issue : 3  |  Page : 365--372

Darbepoetin Use for the Treatment of Anemia in Hemodialysis Patients in Saudi Arabia


Faissal A.M Shaheen1, Nabila Akeel1, Adnan Alfi2, Ali Harbi3, Nauman Tarif4, Mohammad Ziad Souqiyyeh5,  
1 Department of Nephrology in King Fahad Hospital, Jeddah, Saudi Arabia
2 Department of Nephrology, King Abdulaziz and Oncology Center, Jeddah, Saudi Arabia
3 Department of Nephrology, Security Forces Hospital, Riyadh, Saudi Arabia
4 Department of Nephrology, King Khaled University Hospital, Riyadh, Saudi Arabia
5 Department of Nephrology, Saudi Center for Organ Transplantation, Riyadh, Saudi Arabia

Correspondence Address:
Faissal A.M Shaheen
Jeddah Kidney Center, King Fahad Hospital, P.O. Box 11076, Jeddah 21453
Saudi Arabia

Abstract

Erythropoietin replacing proteins have improved patient outcomes and quality of life. Darbepoetin has a 3-fold longer half-life than recombinant human erythropoietin (rHuEPO). In this study, we investigate the efficacy and safety of the conversion of stable hemodialysis patients from the current short-acting r-HuEPO (EPO alfa or beta) to the long-acting darbepoetin. In addition, we verified the appropriateness of the current ratio of conversion of the short acting to the long-acting erythropoietin in an open label prospective multi-center study. The study design included 12 weeks darbepoetin administration. The conversion ratio was 200 IU of short acting r-HuEPO to 1 microgram of darbepoetin. We adjusted the dose of darbepoetin to maintain hemoglobin levels between 110-120 g/L. There were 33 patients who satisfied the entry criteria. The study was conducted from January-June, 2005. The study patients included 18 men and 15 women, the mean age was 50.4 ± 12.3 years and the mean duration on HD was 323 ± 51.9 days. There was a significant decrease in the mean dose of darbepoetin from 37.3 ± 12.9 ug/week at week 1 of the study to 20.8 ± 16.6 ug/week by the end of week 12 (p< 0.00003) while the hemoglobin level was maintained within the previously defined range. The initial conversion ratio from short-acting erythropoietin to darbepoetin was 200 IU to 1 microgram. However, at the end of week 12, the mean dose of darbepoetin decreased to an equivalent conversion ratio to 361 IU: 1 microgram. This may reflect great savings in the cost of treatment. Our experience with darbepoetin reveals that darbepoetin is effective and safe for the treatment of anemia in hemodialysis patients and has a more convenient dosing schedule than short-acting erythropoietin. The darbepoetin dosage decreases over time and savings are expected to greater with darbepoetin more than with short-acting erythropoietin with time.



How to cite this article:
Shaheen FA, Akeel N, Alfi A, Harbi A, Tarif N, Souqiyyeh MZ. Darbepoetin Use for the Treatment of Anemia in Hemodialysis Patients in Saudi Arabia.Saudi J Kidney Dis Transpl 2006;17:365-372


How to cite this URL:
Shaheen FA, Akeel N, Alfi A, Harbi A, Tarif N, Souqiyyeh MZ. Darbepoetin Use for the Treatment of Anemia in Hemodialysis Patients in Saudi Arabia. Saudi J Kidney Dis Transpl [serial online] 2006 [cited 2022 Jan 25 ];17:365-372
Available from: https://www.sjkdt.org/text.asp?2006/17/3/365/35769


Full Text

 Introduction



Erythropoietin replacing proteins have improved patient outcomes and quality of life. Recent research has resulted in the develop­ment of a long-acting erythropoietin, darbepoetin, which is more convenient for administration by physicians and patients.

Darbepoetin alfa is a new hyperglycosylated recombinant erythropoietin protein with a 3-fold longer half-life than recombinant human erythropoietin (rHuEPO). Darbepoetin alfa administered intravenously (i.v.) once weekly or once every other week is an effective treatment regimen for hemodialysis or PD patients with renal anemia.[1],[2],[3] For patients who continued treatment of darbepoetin up to 52 weeks, hemoglobin (Hgb) was maintained between 100 and 130 g/L from mean baseline values of 84 and 87 g/L and the optimal weekly starting dose was 0.45-0.75 ug/kg. [4] Dosing is possible for both the sub­cutaneous (s.c.) and i.v. routes of administration in hemodialysis patients and the i.v. route is even more efficient relative to the short­acting erythropoietin.[5]

Furthermore, darbepoetin has been proven to be effective in maintaining Hgb levels in CKD patients with a s.c. monthly dosing schedule.[6]

The use of darbepoetin in existing patients treated with rHuEPO requires conversion dosing. The current conversion table may underestimate the dose.[7]

A therapeutic interchange program to convert therapy for all inpatients under­going dialysis from erythropoietin alfa to darbepoetin alfa for treatment of chronic kidney disease-related anemia has been implemented and resulted in cost-savings in Europe and USA.[8],[9],[10],[11],[12],[13],[14],[15]

Our primary aim in this study was to establish the efficacy and safety of the darbepoetin conversion of stable hemodialysis patients from the current short-acting r-HuEPO (EPO alfa or beta) to the long-acting darbe­poetin. Our secondary aim was to check the appropriateness of the current ratio of conversion of the short acting to the long acting erythropoietin.

 Methods and Patients



This is an open label prospective multi-center study including the following hospitals: King Fahed Hospital, Jeddah, King Abdulaziz and Oncology Center, Jeddah, Security Forces hospital, Riyadh, and King Khaled University Hospital, Riyadh, Saudi Arabia. The study was conducted between January -June, 2005.

Included in the study were patients who were maintained on chronic hemodialysis for at least 3 months prior to initiating darbepoetin. They were optimally dialyzed as judged by usual dialysis and serum chemistry parameters (KT/V: >1.1) The patients' pre­study hemoglobin levels ranged from 110­120 g/L. All the patients were maintained on stable doses of erythropoietin administered subcutaneously for at least 8 weeks prior to commencement of the study (1500 pg/ml (148 pmol/L over the last 12 months) severe cardiac disease, chronic pulmonary disease associated with functional limitation, malignancy, major organ transplantation or other severe illnesses. All female patients had a negative pregnancy test and were not pregnant or breast-feeding at the time of entry into the study. The patients were not taking drugs that could affect erythropoiesis (e.g. androgens).

The patients had no blood transfusions during the 8 weeks prior to enrollment. Each patient signed an informed consent and had a comprehensive history and physical exam at the beginning and end of the study. The patients continued the same medications they were taking prior to the beginning of the study including antihypertensives and iron supplements.

Lab investigations, which included complete blood count and differential, renal function tests (Urea, creatinine, KT/V urea, electrolytes, calcium, phosphate), liver function tests (total proteins, albumin, liver enzymes, cholesterol and alkaline. phosphatase), iron stores tests (iron, ferritin, iron binding capacity, transferrin saturation), parathyroid hormone level and glucose, were performed at entry, every 4 weeks and at the end of the study.

The study design included 12 weeks of darbepoetin (Aranesp ®, Amgen, USA) at a dose calculated according to the weekly cumulative dose of the short-acting EPO at the time of pre-study assessment visit.

The conversion ratio was 200 IU of short acting r-HuEPO to 1 microgram of darbepoetin. The administration of darbepoetin was i.v. or s.c. using the available pre-filled syringes of 20, 30, 40, 50, and 60 /µg. The dose was adjusted to maintain hemoglobin levels between 110-120 g/L. Complete blood count tests were performed on a weekly basis to monitor hemoglobin levels.

The dose of darbepoetin was increased or decreased by 25% to maintain the hemoglobin level within the set limits on two consecutive Hgb readings. If the highest was surpassed the dose of dar bepoetin was then decreased followed by a reduction in the frequency of dosing.

We followed the safety of darbepoetin that included the nature, frequency, severity, relation to treatment, and outcome of adverse events including the use of antihypertensive medi­cations, IV iron medications, and access related events. Incidence of all adverse events (including serious adverse events) reported by the investigators as related to the study drug would be documented.

 Statistical Analysis



We expressed the results of the age, mean blood pressure (1/3 systolic+2/3 diastolic), hemoglobin levels and doses of the darbepoetin as mean ± standard deviation. Continuous data were analyzed using an independent-sample t test. We compared the means and set the significance level to p th week of darbepoetin administration. Darbepoetin had to be administered every other week in 13/20 (60%) patients to maintain the hemoglobin levels in the maintenance range. This increased the estimated conversion ratio to 400-500 IU:1 microgram, which would have been more appropriate as an initial conversion ratio in our study patients.

There were 13 (40%) HCV+ patients and 20(60%) HCV- patients in our study. We found no significant differences in the mean doses of darbepoetin or mean hemoglobin levels between the two groups over the 12 weeks of the study. None of the patients were on HCV antiviral therapy during the study period.

 Discussion



The patients selected in this study had stable hemoglobin levels with stable doses of short-acting erythropoietin. This ensured that the patients did not have resistance to the short-acting erythropoietin secondary to iron deficiency, inflammation, inadequate dialysis or uncontrolled hyperparathyroidism. The measured clinical and laboratory parameters in our cohort further ascertained the uni­formity of the selection.

The results of our short-term study revealed that hemoglobin levels could be maintained by darbepoetin throughout the study period. All the patients were on s.c. dosing of short­acting erythropoietin prior to conversion. There was a steady decline in the doses of darbepoetin toward the end of the study despite the i.v. route of administration in almost all the patients. Our results are compatible with those of Weiss et al. [16] and Locatelli et al. [1],[17] Furthermore, the patients with unusually high initial doses of darbe­poetin profited most from the decrease of the darbepoetin dose during the study period. This was also the experience of other studies. [18]

The adverse effects were minimal in the study patients. The blood pressure did not need further management during the study period. This also was the experience of others. [1],[2],[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14],[15],[16],[17],[18],[19]

The two study dropouts were not related to the drug administration since both did not show any thrombotic events during dialysis and had stable blood pressure levels during the study period.

We found that the conversion ratio of erythro­poietin to darbepoetin of 200 IU: 1 microgram at the time of conversion may be an over-estimate. A ratio of 361 IU: 1 microgram could maintain the hemoglobin within the recom­mended limits in our study patients; in some patients, the ratio may even be as low 450 IU: 1 microgram. Others recommended similar ratios.[20],[21]

Finally, there was no association of HCV infection and the efficacy of darbepoetin on the hemoglobin levels during our study. Some studies reported similar results of great benefit of darbepoetin even during anti-HCV therapy.[22],[23],[24],[25],[26]

We conclude that the Saudi experience with Darbepoetin reveals that this long­ acting erythropoiesis stimulating agent is effective and safe for the treatment of anemia in patients on hemodialysis. It is more con­venient for dosing than short-acting erythro­poietin. Predialysis stages of chronic kidney disease and peritoneal dialysis patients may benefit even more from the extended periods between doses. There is a decrease in the dose over time and savings are expected with darbepoetin over time relative to short acting erythropoietin.

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