Drug levels in the blood (anti-epileptic drug: Topamax®)

Topamax (active ingredient: Topiramate®, JANSSEN-CILAG GmbH) Topamax is supplied as 25 mg, 50 mg, 100 mg or 200 mg film-coated tablets.

Application
As adjunct therapy in adults and children 2 years and older with

  1. local epileptic seizures with or without secondary generalisation,
  2. primary generalised tonic-clonic seizures and
  3. epileptic seizures due to Lennox-Gastraut syndrome when the patient was not seizure-free with standard treatment consisting of one or more anti-epileptic drugs.

Pharmacological properties
Topiramate is a new anti-epileptic substance whose therapeutic effect is primarily due to three properties:

  1. Topiramate reduces the frequency of the occurrence of action potentials after the depolarisation of neurons. This indicates a condition-dependent blockade of the tension-dependent Na channels.
  2. Topiramate weakly antagonises the excitatory effect of glutamate in specific subtypes (kainate/AMPA) of the glutamate receptor.
  3. Topiramate significantly increases GABA activity (GABA = gamma-aminobutyric acid) with certain GABA receptors.

Contraindications

  1. Known hypersensitivity to the active ingredient.
  2. Topamax should not be given to children under 2 years of age, since there is still insufficient clinical experience for this age group.
  3. Topamax film-coated tablets may be given to pregnant women only if there are no alternative therapies available and the potential benefit outweighs the potential risk.

Particularly in susceptible patients, it may increase the risk of nephrolithiasis.
Topiramate is quickly absorbed, and peak plasma levels are achieved after approx. 2 hours.

Test material
1 ml of serum

Therapeutic range
Dose adjustment is necessary, depending on the efficacy of and tolerance to the drug.

Reference values
Topiramate: 2-5 µg/ml

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