GlaxoSmithkline (GSK) announced that its epilepsy seizure drug Trobalt (retigabine) will no longer be commercially available after June 2017. The company has advised healthcare providers to seek alternative medicines for patients as soon as possible and ensure that all patients are withdrawn from Trobalt by the end of June.
Treatment withdrawal should be done via a gradual dose reduction over at least three weeks and according to patients’ prescriptions, the company said. Healthcare providers also should continue to monitor patients while they remain on Trobalt. Doctors should not prescribe Trobalt to new patients.
Trobalt is a potassium channel opener that was prescribed as an add-on treatment for partial onset seizures, a form of epilepsy in which a seizure begins in a specific area on one side of the brain, with or without secondary generalization. It was prescribed to patients 18 or older for whom other treatment combinations proved inadequate or were not tolerated.
Trobalt was available in 50-mg, 100-mg, 200-mg, 300-mg, and 400-mg tablets. In 2016, GSK announced safety concerns associated with Trobalt, including blue discoloration of the skin and eye abnormalities. The company urged healthcare providers to review prescriptions and reassess the drug’s benefits and risks for patients.
In 2012, GSK began a survey study (NCT01721213) to assess physicians’ and patients’ understanding of the significant risks associated with Trobalt and the effectiveness of an educational program as specified by a risk management plan mandated by the European Medicines Agency.
The survey study recruited 250 patients from several European countries including the United Kingdom, Sweden, Denmark, and Switzerland, and up to 100 patients from Germany, who were using or had filled a prescription for Trobalt at least once in the previous three months. It also included 200 neurologists who had prescribed an anti-epileptic drug at least once in the previous three months leading up to the survey. At least 75 of the neurologists were expected to have prescribed Trobalt. Up to 100 neurologists from Germany participated, with about 50 expected to have prescribed Trobalt.
The study’s main focus was the percentage of patients and neurologists who provided correct responses to a series of questions concerning the significant risks associated with Trobalt. The risks evaluated were described in Trobalt’s patient information leaflet and physician’s guide.
The results of the survey, titled, “European Survey of Prescriber Understanding of Risks Associated with Retigabine,” and published in 2015 in the journal Drugs Real World Outcomes, showed findings only for physicians. It concluded that prescribing doctors were aware of the risks associated with Trobalt. Following this study, GSK initiated another EU survey to evaluate how doctors communicated the specific risks associated with this medication to their patients.