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.

Renagel (Genzyme)
800 mg tablets
Approved indication: hyperphosphataemia in chronic renal disease
Australian Medicines Handbook section 7.8

Patients with end-stage renal disease are at risk of hyperphosphataemia. This is associated with hyperparathyroidism, bone resorption and increased mortality. One strategy to control hyperphosphataemia is to reduce the absorption of phosphate from the gut. This can be achieved with a binding agent such as calcium acetate.

Sevelamer is a polymer which binds phosphates in the gut. The complex is not absorbed, so serum concentrations of phosphate should fall. Patients take tablets with every meal, at a dose determined by the serum phosphorus. The target concentration is 1.78 mmol/L or less.

Several studies have compared sevelamer with calcium acetate. In one study 83 patients having haemodialysis took calcium acetate or sevelamer for eight weeks, then after a two-week washout, swapped to the other drug for eight weeks. The effects on serum phosphate were similar, but patients taking calcium acetate were more prone to develop hypercalcaemia.1

Another comparative study found that although patients given calcium acetate were more likely to develop hypercalcaemia, they were also more likely to reach the target phosphate concentration. This study concluded that calcium acetate should remain the treatment of choice, because of its significantly lower cost.2

The cost-benefit assessment may be changed if the results of an unpublished long-term study are confirmed. This study of more than 2000 patients found reduced mortality in elderly people and patients treated with sevelamer for more than two years. Although the benefit was significant in these sub-groups, there was no significant overall advantage over calcium-based phosphate binders.3

Although sevelamer causes less hypercalcaemia, it may cause more dyspepsia than calcium acetate. In a pooled analysis of 384 patients, 58 discontinued sevelamer because of adverse events. These included dyspepsia, abdominal pain, diarrhoea, nausea and vomiting. As sevelamer binds bile acids there is a theoretical possibility it could reduce the absorption of fat soluble vitamins.

Sevelamer reduces concentrations of low density lipoprotein cholesterol. This could help to prevent cardiovascular calcification in patients having haemodialysis, however this strategy is likely to be more expensive than giving calcium acetate and a lipid-lowering drug.2Until the long-term effects of sevelamer are clearer it seems likely that its use will be determined by its cost.

manufacturer declined to supply data

The Transparency Score ( ) is explained in New drugs: transparency', Vol 37 No 1, Aust Prescr 2014;37:27.