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.
Naramig (Glaxo Wellcome)
2.5 mg film-coated tablets
Indication: migraine
AMH Section 16.3.2
This drug adds to the choice of serotonin (5HT) agonists available for the treatment of migraine. These drugs can be considered for patients who have a history of attacks which do not respond to simple analgesics or ergotamine.
Naratriptan should be taken early in the attack. A tablet produces peak plasma concentrations within 3 hours. The bioavailability of the tablet is higher in women (74%) than in men (63%). There is also a difference in clearance between the sexes. Half of the dose is excreted unchanged in the urine and clearance is affected by liver and kidney disease. The mean half-life is 6 hours.
A large study compared naratriptan with placebo.1 After 4 hours the headache had been reduced in 68% of the 586 patients who had been given naratriptan. This was significantly better than the response (33%) in the patients who took placebo. The headache got worse again within 24 hours in 27% of the naratriptan group and 36% of the placebo group.
Other studies have compared the efficacy of naratriptan with sumatriptan. In general, more patients will obtain relief within 4 hours by taking 100 mg sumatriptan, but the headache is less likely to recur in the patients given 2.5 mg naratriptan.
Adverse events occur in approximately 17% of attacks treated with naratriptan. These include symptoms which can also occur in patients taking sumatriptan, e.g. feelings of heaviness, heat, dizziness, drowsiness and chest pain. As naratriptan causes vasoconstriction, it should not be prescribed for patients with a history of cerebrovascular disease. It is also contraindicated in patients with ischaemic heart disease, uncontrolled hypertension or peripheral vascular disease. If the headache does not respond in 4 hours, a second tablet may be taken, but this is the maximum dose. Giving ergotamine or a derivative concomitantly is not recommended.
Given that the usual dose of sumatriptan is 50 mg, rather than the 100 mg used in the comparative studies, naratriptan is probably equally effective. It may be particularly useful for patients who tend to develop a recurrent headache within 24 hours.
