Topiramate Oral Solution ET-101 Shows Bioequivalence With Topamax


Eton Pharmaceuticals plans to submit a new drug application for ET-101 in the third quarter of 2020, anticipating its formulation to be the first approved oral topiramate solution.

Sean Brynjelsen, MBA, MS

Sean Brynjelsen, MBA, MS

Eton Pharmaceuticals has announced that ET-101, a proprietary oral solution formulation of topiramate—an antiepileptic agent approved for both partial onset and generalized tonic-clonic seizures, and for use as a migraine prophylactic—demonstrated bioequivalence to Topamax (Janssen) in healthy male subjects under fasting conditions.1,2

Results from the study of ET-101 demonstrated the drug’s bioequivalence to the comparator product under fasting condition. Researchers found 90% confidence intervals for all pharmacokinetic parameters all within the 80% to 125% bioequivalence criteria.

Additionally, a separate food effect study, conducted under fed conditions, proved that the bioavailability of the drug is not impacted by food intake.

“We are pleased to report positive results for ET-101, which brings the product 1 step closer to the market. ET-101 represents a very large market opportunity and is an important part of our growing pediatric neurology portfolio,” Sean Brynjelsen, MBA, MS, chief executive officer, Eton Pharmaceuticals, said in a statement.

Topiramate, currently marketed as Topamax, among others, was first approved to treat various forms of epilepsy in adults and children in 1996. Additionally, doctors prescribe the drug for patients 2 years or older whose seizures are associated with Lennox-Gastaut syndrome.3

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The drug got its second FDA approval in 2004, as the FDA expanded its indications to include migraine prevention in patients 12 years or older. Topiramate reduces migraine frequency by calming overactive pain-signal firing but does not have an impact on pain relief of a migraine after it starts.

ET-101 is the third product in Eton’s pediatric pipeline but is expected to be the first oral solution of topiramate approved by the FDA. If approved, it would include the treatment of partial-onset or primary generalized tonic-clonic seizures, primary generalized tonic-clonic seizures, and seizures associated with Lennox-Gastaut syndrome in patients 2 years of age and older, and for the preventive treatment of migraine in patients 12 years of age or older.

Additionally, Eton currently is still developing ET-105, its lamotrigine oral suspension for the treatment of epilepsy and bipolar disorder, and ET-104, a proprietary oral liquid formulation of an undisclosed molecule frequently used to treat a severe neurological condition.

“We believe our proprietary oral liquid formulation will address a critical unmet need for pediatric epilepsy patients and we look forward to bringing the product to them as quickly as possible,” Brynjelsen went on to say in a statement.

Eton announced it anticipates submitting a new drug application (NDA) for ET-101 in the third quarter of 2020. If all goes well, FDA approval for the drug could come as early as the second quarter of 2021.


1. Eton Pharmaceuticals reports positive study results for ET-101 (topiramate oral solution)[news release]. Deer Park, Illinois: Eton Pharmaceuticals; Published March 17, 2020. Accessed March 19, 2020.

2. Topiramate (Topamax) FDA label. Updated October 2012. Accessed March 19, 2020.

3. Miller E, Connoly K, Gabay M. Topamax. Drugwatch website. Updated February 24, 2020. Accessed March 19, 2020.

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