Trip Answers

Question answered:08/02/06 Warning! this question is over two years old.

Suitability of topiramate

Both the NICE guidelines on the management of epilepsies in adults and children, and the guideline on newer drugs for epilepsy in children recommend:

“The newer antiepileptic drugs gabapentin, lamotrigine, oxcarbazepine, tiagabine, topiramate, and vigabatrin (as an adjunctive therapy for partial seizures), within their licensed indications, are recommended for the management of epilepsy in children who have not benefited from treatment with the older antiepileptic drugs such as carbamazepine or sodium valproate, or for whom the older antiepileptic drugs are unsuitable because:
there are contraindications to the drugs
• they could interact with other drugs the child is taking (notably oral contraceptives)
• they are already known to be poorly tolerated by the child
• the child is currently of childbearing potential or is likely to need treatment into her childbearing years. [1 & 2]

The second of these guidelines offers additional information on prescribing topiramate:

“3.7.1 Topiramate is licensed for combination therapy for adults and children older than 2 years who are inadequately controlled on conventional first-line antiepileptic drugs and who have partial seizures with or without secondary generalisation, seizures associated with Lennox–Gastaut Syndrome, or primary generalised tonic–clonic seizures. It is also licensed as monotherapy in adults and children aged 6 years and older with newly diagnosed epilepsy with
generalised tonic–clonic seizures, or partial seizures with or without secondarily generalised seizures.”

Users are warned:  “It appears to have a low potential for drug interactions, but it does interact with oral contraceptives.” [2]

The BNF for Children and the NICE technology appraisal [2] both list potential side effects of topiramate, however neither source indicates at which point during treatment side effects are most likely to occur or whether time increases or diminishes these adverse effects.

We consulted the SPC for topiramate and found a list of adverse events together with prevalence figures, but again no details of when these events might occur during treatment. The BNF entry does include information and advice from the Committee on the Safety of Medicines:

“CSM advice
Topiramate has been associated with acute myopia with secondary angle-closure glaucoma, typically occurring within 1 month of starting treatment. Choroidal effusions resulting in anterior displacement of the lens and iris have also been reported. The CSM advises that if raised intra-ocular pressure occurs:
• seek specialist ophthalmological advice;
• use appropriate measures to reduce intra-ocular pressure;
• stop topiramate as rapidly as feasible.”

Concerning side-effects of topiramate in general  the BNF states that, “If child cannot tolerate titration regimen [detailed in the entry] then smaller steps or longer interval between steps may be used.” [3]

Side effects

Da Silvo Sousa et al clinical study of 22 patients [aged between 13 and 53 years] examined the efficacy of topiramate for treating juvenile myoclonic epilepsy observed:

“Paresthesias and dry mouth were more common during the titration phase and tended to vanish after three months of therapy. These side effects were tolerable and the drug could be maintained in the majority of patients.” [4]

A clinical trial and review article on topiramate by Ormrod and McClelland concludes: “Well controlled studies have demonstrated that topiramate is an effective agent for the adjunctive therapy of partial and generalised tonic-clonic seizures in children. Treatment-limiting adverse events do occur, but these may be managed by slow titration.” [5]

 

References
1. NICE. The epilepsies: the diagnosis and management of the epilepsies in adults and children in primary and secondary care. October 2004. (http://www.nice.org.uk/pdf/CG020NICEguideline.pdf).
2. NICE. Newer drugs for epilepsy in children. April 2004. (http://www.nice.org.uk/pdf/ta079fullguidance.pdf).
3. BNF for Children. Topiramate. 2005 (http://www.bnfc.nhs.uk/bnfc/bnfc/2005/36514.htm?q=%22topiramate%22).
4. SOUSA, Patrícia da Silva, ARAUJO FILHO, Gerardo Maria de, GARZON, Eliana et al. Topiramate for the treatment of juvenile myoclonic epilepsy. Arq. Neuro-Psiquiatr., Sept. 2005, vol.63, no.3b, p.733-737. (http://www.scielo.br/pdf/anp/v63n3b/a01v633b.pdf).
5. Ormrod D and McClellan K. Topiramate: a review of its use in childhood epilepsy. Paediatr Drugs. 2001;3(4):293-319. (http://www.hubmed.org/display.cgi?uids=11354701).

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