GSK’s Trobalt launched in UK
pharmafile | May 25, 2011 | News story | Sales and Marketing | GlaxoSmithKline, Trobalt, epilepsy, retigabine
GSK has launched its new epilepsy treatment Trobalt in the UK.
Trobalt (retigabine) is as adjunctive treatment of partial onset seizures with or without secondary generalisation in adults aged 18 years and above with epilepsy.
The drug, co-marketed globally by GSK and Valeant, will compete with existing epilepsy drugs such as Pfizer’s Lyrica and UCB’s Keppra.
Its unique mechanism of action will help it compete with older off-patent drugs such as GSK’s own Lamictal, J&J’s Topamax and Pfizer’s Neurotin.
The drug acts faster than existing treatments, reaching peak performance levels around 90 minutes after being taken.
It is estimated that around 30% of diagnosed epilepsy sufferers do not respond to initial anti-epileptic drug (AED) treatments and remain uncontrolled. This group is considered to be treatment resistant and equates to around 60,000 people in the UK.
The safety and efficacy of Trobalt was established in two pivotal studies – RESTORE 1 and 2 (Retigabine Efficacy and Safety Trials for Partial Onset Epilepsy) where patients who were treatment resistant were recruited. Trobalt significantly improved seizure control, with a greater number of patients achieving a reduction in the number of seizures by 50% or more, compared with placebo.
The studies also showed that urinary retention occurred at a rate of 0.9% in patients receiving the drug compared to 0.5% on placebo. Across the phase II/III safety population there were four (0.3%) serious adverse events of urinary retention, three of which were known to have resulted in withdrawal. The EU prescribing information therefore recommends that retigabine is used with caution in patients at risk of urinary retention.
Retigabine also caused a prolongation of the QT interval (electrical activity of the heart) when used at the highest dose in healthy volunteers in a thorough QT study. As a precaution, the EU prescribing information recommends that an ECG is recorded before the initiation of retigabine in patients who are taking any medication that may interfere with QT intervals or who may have congestive heart failure, ventricular hypertrophy, hypokalaemia or hypomagnesaemia and in patients initiating treatment who are 65 years of age and above.
Trobalt works primarily by activating a certain family of voltage-gated potassium channels in the brain. The drug could also treat other neurologic conditions, including migraine and neuropathic pain.
A phase II trial to assess the safety and efficacy of retigabine for treating postherpetic neuralgia is ongoing.
Analysts are estimating anything from $200 million to $800 million a year in peak sales forecasts.
The drug has a different chemical name in the US and Canada – ezogabine, and a different brand name, Potiga. The drug is expected to be launched shortly in the US and other major EU markets.
Andrew McConaghie
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