GlaxoSmithKline has today launched Trobalt® (retigabine), the first in a new class of anti-epileptic drug (AED), for the adjunct treatment of adults with partial-onset seizures, and demonstrated significant effects in a treatment resistant patient population.1
Retigabine is the first and currently only AED to target neuronal potassium channels1 which are involved in inhibitory mechanisms in the brain, and are thought to have a role in seizure control.2,3
"Epilepsy is a common disorder that can affect the very young, the elderly and all ages in between. When uncontrolled, it is associated with substantial limitations to quality of life, an increased risk of sudden death and significant costs to the affected individual, to society and to the healthcare system. Trobalt represents a positive addition to the therapeutic armamentarium for the many adult patients with inadequately-controlled focal onset seizures."
Professor Martin J Brodie, Director, Epilepsy Unit, Western Infirmary, Glasgow, UK
The efficacy and safety of retigabine was established in two pivotal multicentre, randomised, double-blind, placebo-controlled, fixed dose studies - RESTORE 1 and 2 (Retigabine Efficacy and Safety Trials for Partial Onset Epilepsy) where patients who were treatment resistant were recruited.4,5 Retigabine 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.4,5
It is thought that of those people diagnosed with epilepsy in the UK, around 30 percent do not respond to initial AED treatments and remain uncontrolled. This group is considered treatment resistant6 and equates to approximately 60,000 people in the UK.7-13
Retigabine, referred to as ezogabine in the US, is being jointly developed by GSK and Valeant.
Retigabine is a first-in-class antiepileptic drug acting on the specific Kv7 potassium channels as adjunct treatment for partial-onset epilepsy.1
To date, retigabine has been tested in 1365 patients across all phase I, II and III studies.4,5 Phase III studies for retigabine demonstrated 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.4,5
Epilepsy is a neurological condition that affects 456,000 people in the UK,14 resulting in brief disturbances in the normal electrical signals of the brain. Partial seizures, which affect part of the brain, are the most common type of seizure experienced by people with epilepsy. Difficult to control/drug resistant epilepsy refers to people who still experience seizures despite taking medication. Currently 30% of those suffering from epilepsy experience this.6
Most non-elective (emergency) epilepsy hospital admissions are due to seizures.15 In 2007-08, epilepsy was responsible for 51,864 episodes of patient care, accounting for 151,007 occupied bed days.15 In the period of 1993-2000, there were about 800 deaths per year where epilepsy was the underlying cause and about 37,000 admissions where epilepsy was the main diagnosis.16
1. Trobalt Summary of Product Characteristics. GlaxoSmithKline; 2011.
2. Shieh CC et al. Gopalakrishnan M. Potassium channels: molecular defects, diseases, and therapeutic opportunities. Pharmacol Rev 2000; 52: 557-594.
3. Trimmer JS, Rhodes KJ. Localization of voltage-gated ion channels in mammalian brain. Annu Rev Physiol 2004; 66: 477-519.
4. Brodie MJ et al. Efficacy and safety of adjunctive retigabine in refractory partial epilepsy. Neurology 2010; 75: 1817-1824.
5. GSK data on file (UK/RTG/0035/11)
6. Schiller Y. Seizure relapse and development of drug resistance following long-term seizure remission. Archives of Neurology. Vol.66, No. 10, October 2009
7. Sander, J.W.A.S. (1990) National General Practice Study of Epilepsy: Newly diagnosed epileptic seizures in a general population. Lancet,336:1267-71
8. Kwan, P. and Brodie, M.J. (2000) Early identification of refractory epilepsy. New England Journal of Medicine, 342:314-319
9. Office of National Statistics (2009). Mid Year Population Estimates 2009: 24/06/10 [online]. Available here. [Accessed 01/03/2010]
10. ISD Scotland (2009) Quality & Outcomes Framework (QOF) for April 2008 - March 2009, Scotland. [online] Available here. [Accessed 01/03/2011]
11. NHS Wales chart of QOF prevalence 2009-2010 - by LHB area Available here. [Accessed 01/03.201]
12. NHS Information Centre (2010). Quality and Outcomes Framework (QOF) for April 2009 - March 2010 England. [online] Available here. [Accessed 01/03/2011]]
13. DHSSPPSNI (2010) Raw Prevalence for Northern Ireland (as of 31 March 2010) [online]. Available here. [Accessed 01/03/2011]
14. Epilepsy Foundation. Seizures and syndromes: prolonged or serial seizures (status epilepticus). Available here. (accessed 6 January 2011)
15. Hospital Episode Statistics (HES online) HES on epilepsy (last accessed 2 February 2011)
16. Brock A. et al., Trends in mortality and hospital admissions associated with epilepsy in England and Wales during the 1990s. Health Statistics Quarterly, no 21, pp 23-29