Topiramate
Topiramate (TopamaxT) is a "newer generation" antiepileptic drug. It is approved in Australia as add-on therapy in patients with various types of epilepsy. It is widely used overseas and its approval has put Australia in-line with international treatment standards.
What are its applications?
Topiramate has been shown to be highly effective in reducing epileptic seizures among patients in a wide variety of seizure types and at varying degrees of severity. It is indicated as an add-on therapy in patients with partial onset epileptic seizures, with or without secondarily generalised seizures, primarily generalised tonic-clonic seizures and drop attacks associated with Lennox Gastaut Syndrome. [REF 1] More than half the patients in a recent Australian study showed a more than 50% reduction in seizure frequency. [REF 2]
Benefits for people with epilepsy
Some patients who have not responded to conventional or newer antiepileptic drugs, may be successfully treated by Topiramate.
A doctor may prescribe Topiramate when the current epilepsy treatment is not satisfactory.
Topiramate has been shown to be effective in producing seizure freedom in up to 10% of (so far untreatable) patients for up to 6 months [REF 3].
Topiramate has a high bioavailability and can be taken with or without food. Its half-life is long (19-23 hours) which means it only has to be taken twice a day. The usual maintenance dose is 200 to 400 mg per day.
Precautions and side effects
If there is a history of kidney stones, it is best to try and drink extra water every day. The doctor should also be informed if the patient is taking any other medicines, especially if they affect the central nervous system and impede reactions. If the patient is taking oral contraceptives (the "pill") then it should be a higher dose "pill" (35 micrograms of oestrogen).
As with all drugs, there is the possibility of side effects. Initially there may be some dizziness, insomnia, headaches, slurred speech, weight loss, nausea or confusion which usually pass. 80-90% of patients, who experienced central nervous system-related side effects (eg. dizziness, confusion,) when first taking Topiramate no longer had them by the fourth month. This means that most side effects are temporary in most patients. Starting on a small dose and building up slowly will reduce side effects.
Sources:
[1]. Approved product information, February 2000.
[2]. Black A. Australian Experience with Topamax. In "Reaching New Heights in Seizure Control". Proceedings of the Topamax launch Symposium, August 1997. Excerpta Medica Communications, 1997.
[3]. Abou-Khalil B, The YOL Topiramate Study Group. Topiramate Therapy in the Long-Term Management of Epilepsy. Epilepsia 1997; 38 (suppl 3): 60 Abstract/Poster. Dr Mark Cook, Epileptologist.
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