FDA Approves Clobazam Add-On for Lennox Syndrome

Allison Gandey

October 24, 2011

October 24, 2011 — The US Food and Drug Administration has approved clobazam (Onfi, Lundbeck) as add-on therapy for seizures associated with Lennox-Gastaut syndrome.

Clobazam is already available outside of the United States in more than 100 countries and is marketed under various brand names, such as Frisium (Hoechst Roussel) and Urbanyl (Sanofi-Aventis).

The new US product has been approved for adults and children aged 2 years and older. It has been granted an orphan drug designation because it is intended to treat a condition that affects fewer than 200,000 people.

Lennox syndrome is responsible for an estimated 1% to 4% of childhood epilepsies. It typically occurs between 2 and 8 years of age. The syndrome often results in delayed psychomotor development and behavior disorders.

This is a difficult condition to treat, and it will be helpful to have an additional treatment option.

"This is a difficult condition to treat, and it will be helpful to have an additional treatment option," Russell Katz, MD, from the FDA's Center for Drug Evaluation and Research, said in a news release.

Clobazam is a benzodiazepine that reportedly increases the inhibitory action of gamma-aminobutyric acid to receptors. The specific mechanism of action by which the drug exerts its antiepileptic effects is unknown.

Clobazam can cause abuse and dependence and has been categorized as a schedule IV drug under the Controlled Substances Act. The FDA is requiring that a medication guide be given to patients and caregivers.

The effectiveness of clobazam, when added to ongoing seizure medication, was established in 2 multicenter controlled studies.

Clinical Trials

"These are the most positive trial results I've ever seen," lead investigator Joan Conry, MD, from the Children's National Medical Center in Washington, DC, told Medscape Medical News in December. Dr. Conry has worked on 35 clinical trials and presented new findings at the American Epilepsy Society 64th Annual Meeting in San Antonio, Texas.

Dr. Conry predicted that clobazam would be on the market in 2011.

Jacqueline French, MD, from New York University's Comprehensive Epilepsy Center in New York City, said after the meeting: "These results have been a long time in coming." She noted, "the compound is and will continue to be useful."

In each study, the drug was tested for the amount of reduction in the weekly frequency of drop seizures. These included atonic, tonic, or myoclonic seizures resulting in a fall or loss of posture from the 4-week baseline to a maintenance period.

In both studies, patients receiving clobazam experienced improved seizure control compared with those receiving the control treatment. In 1 study, the control was placebo, and in the other it was low-dose clobazam. The studies were not head-to-head comparisons with other already-available drugs.

Adverse Events

Common adverse effects reported by patients receiving clobazam included somnolence, sedation, fever, drooling, constipation, cough, urinary tract infection, insomnia, aggression, fatigue, upper respiratory tract infection, irritability, vomiting, trouble swallowing, problems with coordination, bronchitis, and pneumonia.

The FDA warns that clobazam may increase the risk for suicidal thoughts or behaviors in a very small number of people. Patients taking antiepileptic drugs should be monitored for depression and unusual changes in mood or behavior.

Clobazam is manufactured by Catalent Pharma Solutions LLC in Winchester, Kentucky, on behalf of Lundbeck in Deerfield, Illinois.

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