GSK and Valeant’s epilepsy treatment approved
pharmafile | April 8, 2011 | News story | Sales and Marketing | GSK, Trobalt, Valeant, epilepsy
The European Commission has granted marketing authorisation for Trobalt, the new epilepsy drug from GSK and Valeant.
Trobalt (retigabine) has been licenced as an adjunctive treatment of partial onset seizures with or without secondary generalisation in adults aged 18 years and above with epilepsy.
The drug will represent new competition for existing epilepsy drugs such as Pfizer’s Lyrica and UCB’s Keppra.
Analysts say the new drug’s unique mechanism of action will help it establish itself in the therapy area, where older off-patent drugs such as GSK’s own Lamictal, J&J’s Topamax and Pfizer’s Neurotin are widely used.
The drug acts faster than existing treatments, reaching peak performance levels around 90 minutes after being taken.
Valeant has forecast peak sales of up to $1.5 billion, but analysts have been more cautious, estimating anything from $200 million to $800 million a year.
“The European authorisation of retigabine is very welcome as it will provide neurologists within Europe with a new therapeutic option for the management of appropriate patients with uncontrolled partial onset seizures,” said Dr Tony Hoos, senior VP, European medical affairs at GSK.
The European licence was supported by three phase III studies suggesting that more patients with partial onset seizures saw a reduction of 50% or more in seizure frequency compared to placebo, when a 600mg, 900mg or 1200mg dose of retigabine was added to their current anti-epileptic drug (AED) therapy.
The problem of urinary retention has been observed in a small number of patients taking the drug. Trials showed 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.
In the pivotal trials, the most frequently reported adverse events with the use of retigabine in combination with other AEDs (occurring in at least 5 % of subjects and at least twice the placebo rate) were dizziness (23%), fatigue (15%) and a number of other less common side effects. In addition, somnolence occurred in 22% of patients on retigabine compared to 12% on placebo.
“We are very pleased to have reached such an important milestone in the development of retigabine,” said Susan Hall, head of research and development at Valeant. “There is a significant need for new AEDs and retigabine could potentially play an important role in the management of partial onset seizures in appropriate patients.”
The European approval represents the first licence for retigabine. Preliminary authorisation was granted by the Swiss Agency for Therapeutics Products in December 2010. Applications for marketing authorisation have been submitted in six countries in addition to the EU.
In December 2010, GSK and Valeant announced receipt of a Complete Response letter from the FDA for the drug, and are working to submit a response to the US regulator as soon as possible in 2011.
The drug is known by a different chemical name in the US and Canada – ezogabine in the US and Canada.
Andrew McConaghie
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