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Darbepoetin: Maybe not so “Novel”

Since first appearing on the market, Recombinant Erythropoietin preparations have called for 2-3x weekly dosing schedules. And at first glance this appears to be a logical approach, particularly considering the half life of intravenous preparations being limited to ~8.5 hours(1).

With the arrival of NESP (Novel Erythropoiesis Stimulating Protein, a.k.a. Darbepoetin alfa) and an IV half-life 3x longer, an obvious opportunity to market an alternative to Epoetin, one that didn’t need to be injected more than once a week.Darbepoetin Alfa

The fact remains however that subcutaneous Epoetin administration results in a large half-life range(2) of 16-67h. In other words a median half-life of 41.5h. Barely differing to the 48.8h half life of subcutaneous NESP(3)!

And yet subcutaneous NESP is recommended for 1x weekly dosing. Why not take Epoetin 1x weekly instead?
Well that question has since been answered by a 2000 Swedish study who found NO difference between 1x versus 2-3x weekly Epoetin (same total weekly dose).(4)

In fact, as far back as 1992 a study conducted by the Chinese University of Hong Kong uncovered “similar responses” between 1x and 2x weekly subcutaneous administration.(5)

Furthermore it was since revealed that as little as once MONTHLY Darbepoetin alfa was effective at maintaining Hemoglobin levels in stable dialysis patients.(6)

One might conclude that any patient considering 1x weekly subcutaenous Darbepoetin alfa in the interests of convenience may very well reduce their costs considerably by opting for 1x weekly rhEPO instead.

(1) Pharmacokinetics of novel erythropoiesis stimulating protein compared with epoetin alfa in dialysis patients
(2) profile of Epoetin Alfa
(3) An overview of the efficacy and safety of novel erythropoiesis stimulating protein (NESP)
(4) The efficacy of once weekly compared with two or three times weekly subcutaneous epoetin beta: results from a randomized controlled multicentre trial. Swedish Study Group.
(5) Once weekly versus twice weekly subcutaneous administration of recombinant human erythropoietin in haemodialysis patients
(6) Darbepoetin alfa administered once monthly maintains haemoglobin levels in stable dialysis patients