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.

Pariet (Janssen-Cilag)
10 mg and 20 mg enteric-coated tablets
Approved indications: peptic ulcer, gastro-oesophageal reflux disease
Australian Medicines Handbook Section 12.1.4

Rabeprazole is the fourth proton pump inhibitor to be approved in Australia. The other members of the class are omeprazole, lansoprazole and pantoprazole. These drugs are potent inhibitors of acid secretion.1

The suppression of acid secretion begins within an hour of taking rabeprazoleand lasts for up to 48 hours. This duration of action is much greater than the one hour half-life. The drug is metabolised by the cytochrome P450 system(CYP3A4 and CYP2C19) with most of the metabolites appearing in the urine.

Rabeprazole has been compared with omeprazole for each of its approved indications. Although many patients with duodenal ulcer will require treatment for Helicobacterpylori, the proton pump inhibitors can also be effective. After four weeks of treatment rabeprazole and omeprazole had healed more than 90% of the patients. Similar results were found after treating patients with gastric ulcers for six weeks, and patients with erosive or ulcerative gastro-oesophageal reflux disease for eight weeks. If patients with gastro-oesophageal reflux take rabeprazole or omeprazole for a year only about 5% will have a relapse.

Like other proton pump inhibitors rabeprazole is well tolerated. The commonest complaints in clinical trials included diarrhoea, headache and nausea. There have been reports of erythema and bullous skin reactions.

The product information states that rabeprazole does not have clinically significant interactions with other drugs metabolised by cytochrome P450. Rabeprazole does, however, interact with digoxin and ketoconazole.

Although rabeprazole may reduce the pain of peptic ulcer more than omeprazole, it has no clear advantage. The cost of rabeprazole may determine if it is widely prescribed.