The dose equivalent ratio for intravenous epoetin alfa and intravenous darbepoetin alfa used in Australian haemodialysis patients
Background: Based on the Australian Product Information for darbepoetin alfa (ARANESP®, Amgen) the dose equivalent ratio for intravenous (IV) epoetin alfa (EPREX®, Janssen-Cilag) and IV darbepoetin alfa is 240:1. However, no published data are currently available to support this estimate of dose equivalence.
Objective: The purpose of this study was to determine the dose equivalent ratio for IV epoetin alfa and IV darbepoetin alfa used in Australian haemodialysis patients.
Methods: Data on 187 haemodialysis patients from 16 Australian dialysis centres who switched from IV epoetin alfa to IV darbepoetin alfa during the period 1 July 2002 to 31 March 2004 were extracted from the Renal Anaemia Management (RAM) database. The dose equivalent ratio was calculated using a mixed-effects model and by dividing the last epoetin alfa dose prior to switch by the darbepoetin alfa dose.
Results: Most patients were male (58%), without diabetes (81%), aged 59±14 years. The haemoglobin levels prior to switch were 10.9g/dL (95% CI: 10.7, 11.2). At switch, the geometric mean dose ratio was 179:1 (95% CI: 151, 213) using the modeling approach and the most common ratio observed was 200:1. The dosing of darbepoetin alfa remained stable over 180 days and the mean dose ratio at the last recorded dose of darbepoetin alfa was 207:1 (95% CI: 171, 251). The direct calculation produced the same geometric means with narrower confidence intervals.
Conclusion: The dose equivalent ratio for IV epoetin alfa and IV darbepoetin alfa was 179:1 at the time of switch in these Australian haemodialysis patients.