Topiramate | Epilepsy clinician handbook
- Topiramate has a broad range of seizure efficacy and on the Australian PBS can be considered in treatment for focal onset seizures, primary generalised tonic-clonic seizures, and seizures associated with Lennox Gastaut Syndrome not controlled satisfactorily by other anti-seizure medications.
- It has been used in neonates and infants.
Possible side effects
- Marked loss of appetite/loss of weight may occur and require cessation of the drug.
- As topiramate is a carbonic anhydrase inhibitor, metabolic acidosis is a common finding in young infants. Blood bicarbonate levels around 16-18mmol/L are to be expected and usually cause no significant problems. Lower levels may require treatment.
- Nephrocalcinosis can occur and children on long-term treatment or who have other risk factors can be monitored with urine studies and renal ultrasound.
- Reduced sweating may cause heat intolerance which is manageable with simple measures. Care must be taken in warm climates. In the very young heat intolerance can be a more serious side effect and overheating must be avoided.
- Word-finding difficulty and language impairment can occur and are more of a risk with higher doses.
- Sedation can occur but is more common with higher doses.
- Mood disturbance (irritability, agitation, depression) can occur.
- Glaucoma is a contraindication. Advise urgent review if painful eyes develop.
- Rarely, visual field defect is described.
- Paraesthesia and hand tingling can occur but are uncommon.
- All anti-seizure medications are potentially teratogenic and this is often dose related (see section: ASM Prescribing - Pregnancy)
- For a complete list of adverse effects, appropriate formularies should be consulted.
All anti-seizure medications are potentially teratogenic and this is often dose related. For a complete list of adverse effects, appropriate formularies should be consulted.
Interactions and precautions
Precautions
- Topiramate may decrease serum concentrations of oestrogens.
- Topiramate may increase toxicity of sodium valproate.
- Topiramate concentration may be decreased by carbamazepine.
Pregnancy and topiramate
- All anti-seizure medications are potentially teratogenic and this is often dose related
Monitoring
- Drug level monitoring is not routinely utilized or readily available.
- Blood bicarbonate should be checked within a month as a guide and then at intervals with dose escalation. This is particularly important in the infant.
- Renal ultrasound and urine testing are considered as necessary, particularly if back pain or haematuria.
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