Klonopin (clonazepam) is usually used as an "add-on" medication for people who continue to have seizures while taking other seizure medicines, or sometimes as a medication of last resort after most others have failed. It sometimes loses its efficacy after a while.

Klonopin has been available in the United States since 1975, so doctors have plenty of experience with its use, but few large, well-controlled studies of its effectiveness have been performed. It has been shown to work for many different seizure types.

It can be used to treat absence seizures, often in combination with Depakote (valproate). Klonopin is particularly effective against some types of myoclonic seizures such as juvenile myoclonic epilepsy and progressive myoclonic epilepsy. Again, it is often used in combination with Depakote.

Klonopin is useful for seizures brought on by flashing lights (photosensitivity).

Children with Lennox-Gastaut syndrome also frequently benefit from its use, though not all studies have found it helpful for long-term treatment.

Klonopin is usually regarded as less effective against partial seizures than carbamazepine (Tegretol or Carbatrol) or phenytoin (Dilantin, Phenytek).

Factors influencing the decision about whether to add Klonopin to a regimen of seizure medicines that are not fully controlling a person's seizures may include potential interactions, side effects, and the mechanisms of action of the various medications. No single combination is perfect for everyone. Sometimes, a series of combinations must be tried before finding what is best for the individual.

Here is a link to a summary of one clinical trial of clonazepam (Klonopin):

Mikkelsen B, Birket-Smith E, Bradt S, et al. Clonazepam in the treatment of epilepsy. A controlled clinical trial in simple absences, bilateral massive epileptic myoclonus, and atonic seizures. Arch Neurol. 1976;33(5):322-325. PMID: 817696

This small study reported very good results when clonazepam (Klonopin) was used as add-on therapy. Most patients experienced side effects, but they were usually tolerable.

Reviewed February 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.