Clonazepam Medication Description DescriptionClonazepam, sold under the brand Klonopin among others, is a medication used to prevent and treat seizures, panic disorder, and the movement disorder known as akathisia. It is a tranquilizer of the benzodiazepine class. It is taken by mouth. It begins having an effect within 1 hour and lasts between 6 and 12 hours. Onset of action: Within an hour Duration of action: 6–12 hours Elimination half-life: 18–60 hours Drug class: Benzodiazepine Metabolism: Liver (CYP3A) Bioavailability: 90% Metabolites: 7-aminoclonazepam; 7-acetaminoclonazepam; 3-hydroxy clonazepam