topiramate: clinical use

Prescribing considerations

• Avoid abrupt withdrawal because seizures or increased seizure frequency can occur.
• Assess renal function, kidney-stone risk, metabolic-acidosis risk, eye history, mood and cognitive vulnerability.
• Implement the Pregnancy Prevention Programme for every patient who could become pregnant.
• Review weight and nutritional status, especially in children and people losing weight.

Contraindications and cautions

• Hypersensitivity to topiramate or a formulation excipient.
• Migraine prevention during pregnancy.
• Epilepsy during pregnancy unless no suitable alternative treatment exists.
• Use in a patient who could become pregnant unless Pregnancy Prevention Programme conditions are fulfilled.

Monitoring

• Serum bicarbonate when risk factors or symptoms of metabolic acidosis are present.
• Weight, appetite and, in children, growth.
• Mood, behaviour, cognition and suicidal ideation.
• Urgent ophthalmic assessment for acute visual symptoms or eye pain.
• Pregnancy status, contraception and continued need for treatment through regular review.

Clinical pharmacology

Topiramate has multiple neuronal actions involving voltage-dependent sodium channels, GABA-A signalling, AMPA/kainate glutamate receptors and carbonic anhydrase. It is eliminated mainly unchanged by the kidneys.

Formulation and product differences

• Film-coated tablets are swallowed whole.
• Oral suspension must be shaken and measured with the supplied syringe.
• Oral solution is measured with its supplied syringe and may contain clinically relevant excipients, including ethanol, depending on the product.
• Sprinkle capsules can be swallowed whole or opened onto soft food; granules must not be chewed or stored after mixing.

Capsule

Route: Oral

Strengths: 15 mg, 25 mg, 50 mg

Oral solution

Route: Oral

Strengths: 20 mg

Oral suspension