[Therapeutic drug monitoring of topiramate]

Topiramate, a second generation anticonvulsant drug, is marketed in France since 1997. It is also indicated in the prophylaxis of headache and is used, except legal notices, in the treatment of neuropathic pains and bipolar disorders. The efficiency and the risk of adverse reactions are dose dependent. However, the good correlation between the dosage and the plasmatic concentrations, and the relatively low interindividual variability, when we take into account the age and the association with an enzyme inducer, are not in favour of the interest of a dosage. Furthermore, there is a covering range between the effective and not effective concentrations, and levels susceptible or not to facilitate the appearance of an adverse event. There is no validated therapeutic range, but to the usual dosages the plasma concentrations are included between 5 and 20 mg/L (15-60 micromol/L), mostly in the low part of this interval. For this molecule, the level of proof of the interest of the TDM was estimated in: possibly useful.