(Reuters) - Eton Pharmaceuticals Inc said on Friday the U.S. Food and Drug Administration declined to approve its anti-seizure drug lamotrigine, sending the drugmaker's shares down 13% in extended trading.
Eton was notified that its privately held partner Azurity Pharmaceuticals received a complete response letter from the health regulator for lamotrigine, it said in a regulatory filing.
Lamotrigine was one of the three drugs in Eton's neurology portfolio that the drugmaker sold to Azurity Pharmaceuticals last year for up to $45 million in milestone payments.
The drug is a liquid form of a widely available anticonvulsant or antiepileptic oral tablet, which also goes by the name lamotrigine. It helps stabilize electrical activity inside the brain and makes it harder for certain neurons to get stimulated, thus preventing seizures.
The drugmaker did not disclose the details of the complete response letter and added that it was assessing the FDA's comments along with its partner.
Eton and Azurity did not immediately respond to Reuters' requests for more details on the complete response letter.
In 2020, the FDA declined to approve the use of the drug, citing the need for an additional study to show that patients can prepare and administer the oral suspension safely and effectively.
The drugmaker's partner submitted results from the additional study to the FDA in the fourth quarter of 2021.
(Reporting by Bhanvi Satija and Mrinalika Roy in Bengaluru; Editing by Amy Caren Daniel)