Trobalt (retigabine) is an anti-epileptic medicine with a new mechanism of action. It is approved as add-on therapy in adults above 18 years of age with partial-onset seizures with or without secondary generalization.
In the pivotal studies, a significant dose-related reduction in the number of partial attacks was seen for retigabine as compared to placebo, 12-18 % (600mg), 24-28 % (900mg) and 33-36 % (1200mg), respectively. All patients enrolled had seizures that were not adequately controlled with treatment of 1-3 concomitant antiepileptic drugs.
Retigabine belongs to the category of anti-epileptic drugs with the most frequent CNS as well as other adverse events. Some of the adverse effects show dose-response relationship; for some the relation to dose is less clear ranging from 63-81 % for the retigabine treatment groups as compared to 48,2 % in the placebo groups. Adverse reaction related to voiding dysfunction and urinary retention were reported for 5% of the retigabine treated group and retigabine must be used with caution in patients at risk of urinary retention. Caution should be taken when retigabine is prescribed with medicinal products known to increase QT interval as well as in patients with known prolonged QT interval or One should be precautious when prescribing retigabine to patients with known cardiovascular disease.
Most of the adverse effects occurred within the first 8 weeks of treatment.
There are limited data on security and efficacy of retigabine in patients >65 years of age, therefore, a reduction in both start and maintenance dose is recommended in such patients.
IRF finds that the effect of Trobalt (retigabine) is comparable to other new anticonvulsants that are approved for add-on treatment in refractory epilepsy. However, the extent of adverse effects and, above all, the lack of entirely clear dose-adverse relationship makes retigabine less favorable than other anticonvulsants presently at the market. Furthermore, retigabine is about 25 % more expensive than the current most expensive add-on treatment (Vimpat – lacosamide) on the national recommendation list. Retigabine should therefore only be prescribed in patients not responding adequately to or not tolerating other anti-epileptic drugs.
Trobalt (retigabine) was marketed on May 16th, 2011. There is general reimbursement for Trobalt.
The Institute for Rational Pharmacotherapy, May 30th, 2011.