Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.
Aranesp (Amgen)
prefilled syringes containing 10 microgram/0.4 mL, 20 microgram/0.5 mL, 30 microgram/0.3 mL, 40 microgram/0.4 mL, 50 microgram/0.5 mL, 60 microgram/0.3 mL and 100 microgram/0.5mL
Approved indication: anaemia of chronic renal failure
Australian Medicines Handbook Section 7.5
In chronic renal failure erythropoiesis is reduced leading to a normochromic, normocytic anaemia. This can be treated by giving the patient recombinant erythropoietin to stimulate red cell production.
Although there are genetically engineered differences in its structure, darbepoetin can be used as an alternative to erythropoietin. The structural differences give darbepoetin a half-life three times longer than that of erythropoietin. After intravenous injection the half-life ranges from 12 to 40 hours and ranges from 27 to 89 hours after subcutaneous injection. Patients therefore need less frequent injections if they use darbepoetin instead of erythropoietin. A weekly injection should raise the haemoglobin by at least 10 g/L in four weeks, if the patient has adequate stores of iron. The product information explains how to calculate the dose of darbepoetin when switching a patient from erythropoietin.
In clinical trials darbepoetin and erythropoietin have had similar efficacy in the correction of anaemia. Both drugs are also effective at maintaining the haemoglobin concentration.
The adverse effects of darbepoetin resemble those of erythropoietin. Patients find the subcutaneous injection of darbepoetin more painful, but when given intravenously it causes less thrombosis of the vein than erythropoietin. Other adverse events include hypertension and myalgia. Uncontrolled hypertension is a contraindication to darbepoetin. So far there have been no reports of serious allergic reactions or patients developing antibodies to darbepoetin.
