clonazepam, drug used to treat panic disorder and certain seizure disorders. Clonazepam is classified as a benzodiazepine, a group of therapeutic agents characterized by their ability to depress activity in the central nervous system (CNS), resulting in calming, sedative effects. Common trade names for clonazepam include Klonopin and Rivotril.
Clonazepam was developed in the early 1960s by Austro-Hungarian-born American chemist Leo Sternbach and his colleagues at the pharmaceutical company Hoffmann-La Roche. It was approved by the U.S. Food and Drug Administration in 1975 for use in the treatment of panic disorder and seizure disorders, such as epilepsy, complex partial seizures, and absence seizures. Clonazepam soon became an important drug for these conditions, particularly because it has a lower likelihood for dependence and less severe side effects than barbiturates, which were widely used sedatives at the time.
Clonazepam works by binding to the gamma-aminobutyric acid A (GABAA) receptor in the CNS, which increases the receptor’s affinity for the inhibitory neurotransmitter GABA. Enhanced GABA activity reduces the transmission of neural impulses in the brain, thereby attenuating the excitability of neurons that are associated with anxiety and panic. This ultimately has a calming effect on the brain.
In addition to its use in the management of panic and seizure disorders, clonazepam is sometimes also used in the treatment of seizures in children, particularly petit mal absences, as well as for certain anxiety-related disorders, such as social anxiety disorder. The drug also has various off-label uses, including as a treatment for insomnia, restless leg syndrome, and tardive dyskinesia.
Clonazepam is associated with various side effects, including drowsiness, frequent urination, and increased salivation and sweating. More problematic effects can include blurred vision, hallucinations, loss of coordination, muscle pain, loss of memory, sexual dysfunction, shaking, and sleep disturbances. Excessive sedation and coma can occur in severe cases. Clonazepam can also be habit forming and in some instances can lead to physical dependence, requiring a gradual tapering off in dosage to prevent withdrawal symptoms when medication is stopped. Grapefruit adversely influences the effectiveness of clonazepam, and the drug is known to interact with certain other medications, particularly antihistamines, antidepressants, and the anti-arrhythmic drug amiodarone, which can alter its activity and effectiveness.