Published: 13 December 2017

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Spotlight on Topiramate: Seize the Day

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Prescriber Update 38(4): 53-54
December 2017

This article on topiramate is the second in the spotlight series where Medsafe reviews the safety information on a specific medicine or class of medicine.

Indications

Topiramate is indicated in adults and children aged two years and over:

• as monotherapy in patients with newly diagnosed epilepsy
• for conversion to monotherapy in patients with epilepsy
• as add-on therapy in partial onset seizures, generalised tonic-clonic seizures or seizures associated with Lennox-Gastaut syndrome^1,2.

Topiramate is also indicated for the prevention of migraine headache in adults^1,2.

Contraindications

The only contraindication for use of topiramate is hypersensitivity to any component of the product^1,2. Excipients are listed in the data sheet, consumer medicine information (www.medsafe.govt.nz/Medicines/infoSearch.asp) and in the product application search on the Medsafe website (www.medsafe.govt.nz/regulatory/DbSearch.asp).

Warnings and Precautions

Suicidality, Mood Disturbances, Depression

Antiepileptic medicines have been associated with suicidal thoughts and behaviour, regardless of the indication³. In addition, an increased incidence of mood disturbances and depression has been observed during topiramate treatment^1,2.

Inform patients, their families and caregivers of the potential increase in risk of suicidality. Advise patients to seek immediate medical advice if they have any concerns about changes in mood or behaviour.

Oligohydrosis, Hyperthermia

Increases in body temperature resulting from decreased sweating (oligohydrosis) and an inability to sweat normally (anhidrosis) have been reported mostly in children^1,2. Some cases have resulted in hospitalisation. With hot summer days ahead, remind patients, their families and caregivers to watch for signs of decreased sweating and increased body temperature. Take care when prescribing other medicines that predispose patients to heat-related disorders^1,2.

Nephrolithiasis

Some patients may be at increased risk for renal stone formation (nephrolithiasis)^1,2. Signs and symptoms include renal colic, renal pain or flank pain. Advise patients to remain well hydrated to reduce the risk of renal stone formation.

Eye Disorders

A syndrome consisting of acute myopia associated with secondary angle closure glaucoma has been reported^1,2. Visual field defects independent of elevated intraocular pressure have also been reported^1,2.

Other

Administer topiramate with caution in patients with hepatic impairment as the clearance of topiramate may be decreased^1,2. Patients with renal impairment may require a longer time to reach steady state so be careful with any dose adjustments^1,2.

Hyperchloremic, non-anion gap, metabolic acidosis is associated with topiramate treatment^1,2.

Hyperammonemia with or without encephalopathy has been reported^1,2. The risk appears to be dose-related and has been reported more frequently when topiramate is used with sodium valproate. Clinical symptoms often include acute changes in level of consciousness and/or cognitive function with lethargy.

Please refer to the medicine data sheets for further information on topiramate (www.medsafe.govt.nz/Medicines/infoSearch.asp).

New Zealand Reports of Adverse Reactions

From January 2012 to 30 September 2017 the Centre for Adverse Reactions Monitoring (CARM) received 24 reports in which topiramate was reported as a suspect medicine. Of the 24 reports, the reported indications for use were migraine or migraine prophylaxis (14), epilepsy (6), an unapproved indication (3) and unknown (1).

The reports included a total of 56 reaction terms. The top three System Organ Classes with the most reaction terms were psychiatric disorders (14), nervous system disorders (10) and special senses (7). The most frequently reported reaction terms were paraesthesia distal (3), numbness localised (2), dysgeusia (2), and weight decrease (2).

References

1. Janssen-Cilag (New Zealand) Ltd. 2016. Topamax New Zealand Data Sheet 23 August 2016. URL: medsafe.govt.nz/profs/Datasheet/t/topamaxtabcap.pdf (accessed 5 October 2017).
2. Teva Pharma (New Zealand) Limited. 2017. Topiramate Actavis New Zealand Data Sheet 30 May 2017. URL: medsafe.govt.nz/profs/Datasheet/t/topiramateactavistab.pdf (accessed 5 October 2017).
3. 2016. Antiepileptic medicines and suicide. Prescriber Update. 37(1): p. 6–7. URL: www.medsafe.govt.nz/profs/PUArticles/March2016/AntilepilepticMedicinesAndSuicide.htm (assessed 22 November 2017).