The treatment is approved by the U.S. Food and Drug Administration as an add-on therapy for Lennox-Gastaut syndrome, a childhood epilepsy disorder. It can also be prescribed off-label in Batten disease, either as a preventative measure or as a rescue medication to stop a seizure, as part of an agreed emergency seizure management plan.
How Onfi works
Nerve cells communicate with each other via electrical signals and chemical messengers called neurotransmitters that are normally kept tightly regulated. During a seizure, this regulation is lost and the nerve cells are overstimulated, resulting in too many signals being sent.
Onfi is a type of benzodiazepine that works to reduce the amount of signal being sent by the nerve cells. Benzodiazepines bind to and activate a protein found on the surface of nerve cells called GABA receptors. GABA receptors are normally involved in preventing nerves from sending signals when the neurotransmitter GABA binds to them. Onfi can also bind to GABA receptors and reduce the number of signals being sent. This can help restore the balance in the brain, preventing overstimulation and ending a seizure.
Unlike other benzodiazepines, Onfi has a greater affinity for one particular type of GABA receptor and therefore causes fewer sedation side effects.
Onfi in clinical trials
Onfi has not been tested in clinical trials specifically for Batten disease. However, there have been several trials assessing its effectiveness in managing seizures. For example, two key clinical trials assessed the safety and effectiveness of Onfi in managing seizures in Lennox-Gastaut syndrome.
The first was a randomized, double-blind Phase 2 trial (NCT00162981) called OV-1002. It enrolled 68 patients and assessed the effects of a high and low dose of Onfi. The results, published in the journal Epilepsia, demonstrated that a high dose of Onfi could safely and effectively reduce seizures.
The second was a randomized, placebo-controlled Phase 3 trial (NCT00518713) called OV-1012. It enrolled 238 patients at sites globally, to receive a low, medium, or high dose of Onfi or a placebo. The results, published in the scientific journal Neurology showed that seizures were significantly decreased with all doses of Onfi compared to the placebo, with the highest dose being most effective.
Patients from both trials were invited to take part in a long-term open-label extension study (NCT01160770) to assess the long-term safety and effectiveness of Onfi. The results, published in Neurology, revealed no new safety concerns after two years. While some patients required an increased dosage of Onfi, the majority of patients did not develop a tolerance to the treatment and it remained effective at reducing seizures.
Common side effects of Onfi include drowsiness, fever, constipation, aggression, irritability, drooling, and uncoordinated movements or speech.
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