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.
Cosudex (ICI Pharmaceuticals)
50 mg tablets
Indication: prostate cancer
At present, the best treatment for metastatic prostate cancer is androgen ablation. This may be achieved by orchidectomy, antiandrogens or gonadotrophin releasing hormone agonists.1
Bicalutamide is an antiandrogen which has been approved for use in combination with a gonadotrophin releasing hormone agonist. If the treatments begin simultaneously, the 'flare' reaction1 associated with the agonist may be controlled.
One tablet is taken each day. As the drug is metabolised in the liver, no dose adjustment is required if renal function is reduced. In patients with severe liver dysfunction, bicalutamide may accumulate. Accumulation also occurs with routine doses as the half-life of bicalutamide is approximately one week.
Some of the adverse effects of treatment can be expected from the antiandrogenaction of bicalutamide e.g. hot flushes and breast symptoms. Other adverse effects include diarrhoea, nausea and vomiting. Liver function should be tested as it may be affected by bicalutamide.
Flutamide is already available for this indication and it is uncertain if bicalutamide offers any significant advantages. An industry sponsored study found no difference in survival between the two treatments.2 Although the time to treatment failure was shorter for flutamide, the definition of treatment failure was not restricted to progression of the disease. More patients taking flutamide 'failed treatment' because more of them were withdrawn due to a higher incidence of diarrhoea.
The mortality in patients given a combination of an antiandrogen and a gonadotrophin releasing hormone agonist is 56% after 40 months. As the mortality in castrated patients is 58%, drug treatment does not have a significant advantage and costs more.3
