FDA declines to approve Amneal’s novel carbidopa, levodopa formulation for Parkinson’s

The FDA has declined to approve Amneal Pharmaceuticals’ new drug application for IPX203, a novel, oral formulation of extended-release carbidopa/levodopa designed for the treatment of Parkinson’s disease.

According to a press release from Amneal, the company received a complete response letter from the FDA indicating that although an “adequate scientific bridge” was established for the safety of levodopa based on pharmacokinetic studies, it was not established for carbidopa. As a result, the FDA has requested additional information.

“We are committed to advancing IPX203 for Parkinson’s disease, which has been developed to provide a longer duration of therapeutic benefit than existing formulations with fewer doses,” Chirag Patel and Chintu Patel, co-CEOs at Amneal, said in the release. “We plan to work closely with the FDA to address the agency’s feedback and we remain confident in bringing this new treatment to Parkinson’s patients as soon as possible.”

Amneal’s NDA submission was based on results from the phase 3 RISE-PD clinical trial, which showed IPX203’s extended-release offered significantly more “good on” time, as well as significantly less “off” time, compared with immediate-release carbidopa/levodopa, even with less frequent doses. The new formulation is distinct from Rytary, the company’s extended-release carbidopa/levodopa treatment, which received FDA approval in 2015.

In its letter, the FDA identified no issues regarding efficacy or manufacturing of IPX203. Amneal said it will work closely with the FDA to address its comments and plans to meet with the agency to identify next steps.