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.
150 mg and 500 mg tablets
Approved indication: breast cancer
Australian Medicines Handbook Section 14.1.3
Drug treatment has an increasing role in the management of breast cancer.1 New drugs for breast cancer are usually first used when all else fails. Capecitabine may be indicated for women with locally advanced or metastatic breast cancer after an anthracycline-containing regimen and paclitaxel have failed.
After capecitabine is absorbed from the gut, it is converted to the active cytotoxic 5-fluorouracil (5FU). One of the enzymes involved in the conversion is more concentrated in tumours than normal tissues. The metabolism of 5FU damages cells, especially those which are rapidly proliferating. Most of a dose is excreted as metabolites in the urine. Capecitabine and 5FU both have a half-life under one hour, but only two doses a day are needed. Patients take the drug for two weeks, then have a week's rest. The dose is adjusted according to its toxicity.
Diarrhoea, nausea and vomiting are the most common adverse effects of capecitabine. Approximately 45% of patients develop a hand and foot syndrome. There is peripheral numbness, paraesthesia, erythema, swelling and blistering. If these symptoms are severe, treatment should be interrupted. Other adverse effects include stomatitis, fatigue and abdominal pain.
There has only been one large uncontrolled clinical trial of capecitabine. Most of the 162 patients were resistant or had failed previous treatment; 82% had already been exposed to 5FU. There were only 3 complete responses and the overall response rate was 20%. The patients survived for a median of 13 months. Patients should be informed about the marginal efficacy and frequent adverse effects.