Explainer: What is epibatidine?

Western governments have claimed that the Russian state killed the imprisoned opposition politician Alexei Navalny in 2024 with an obscure toxin called epibatidine. Speaking at a security conference in Munich, the UK’s foreign secretary Yvette Cooper said that: ‘Only the Russian government had the means, motive and opportunity to deploy this lethal toxin against Alexei Navalny during his imprisonment in Russia.’

Following the announcement, representatives of the UK, Sweden, France, Germany and the Netherlands have written to the director general of the Organisation for the Prohibition of Chemical Weapons stating that Russia is in breach of the Chemical Weapons Convention. So what is epibatidine and why has it been linked to Navalny’s death?