Trial testing Crexont for advanced Parkinson’s kicks off in Europe
First patient dosed; trial of under-review therapy still enrolling adults
- A clinical trial dubbed ADIP, testing extended-release Crexont for advanced Parkinson's disease, has dosed its first participant.
- The oral medication aims to reduce motor fluctuations and off episodes by maintaining steady levodopa levels.
- The Phase 3b trial, underway in Europe, is still recruiting adults with Parkinson's.
Zambon Biotech has dosed the first patient in its clinical trial testing Crexont (IPX203) — an extended-release formulation of carbidopa/levodopa (CD/LD) that aims to ease so-called off episodes — among people with advanced Parkinson’s disease.
With several locations now open in Italy, Poland, and Spain, the Phase 3b clinical trial, dubbed ADIP (EUCT 2025-521772-57-00), is assessing the effectiveness of the oral medication versus an immediate-release CD/LD regimen, Zambon stated in a company press release announcing the trial’s launch.
ADIP is still recruiting up to 92 adults who have been on stable doses of an immediate-release CD/LD formulation for at least six months but continue to experience motor fluctuations.
Crexont was approved in the U.S. in 2024 for people with Parkinson’s and is currently under review by Health Canada. In June 2025, the company submitted Crexont for regulatory approval to the European Medicines Agency.
“Dosing the first person in our Phase 3b ADIP study marks an important milestone for our company and for the people living with Parkinson’s disease who urgently need new therapies that truly improve their quality of life and the therapeutic outcomes,” said Mathias Knecht, MD, Zambon’s chief medical officer.
Parkinson’s disease is caused by the progressive loss of dopaminergic neurons, the nerve cells that produce dopamine, a signaling molecule involved in motor control. CD/LD is a standard combination for treating Parkinson’s. Levodopa is a precursor to dopamine, used to increase dopamine levels in the brain. Carbidopa prevents levodopa’s conversion to dopamine before it reaches the brain.
Extended-release Crexont aims to keep levodopa levels steady
Crexont is an extended-release formulation that contains immediate-release CD/LD granules and extended-release coated beads of levodopa. This combination enables the medication to maintain steady levels in the bloodstream, according to the developer.
It may also prevent off episodes, or motor fluctuations — periods when symptoms return between levodopa doses — and increase good on-time periods, when symptoms are well-controlled without dyskinesia, or involuntary movements.
An earlier Phase 3 trial, called RISE-PD (NCT03670953), had tested the medication in 506 adults with advanced Parkinson’s who were experiencing motor fluctuations. In that trial, Crexont was associated with more daily good on time and reduced off periods compared with patients given a standard immediate-release CD/LD formulation.
Moreover, Crexont achieved benefits at an average of three daily doses, while the immediate-release formulation was dosed on average five times per day. The trial was followed by a nine-month open-label extension study (NCT03877510), which found that CREXONT remained safe and effective in controlling motor fluctuations in the long term.
The new ADIP trial is an open-label study — one in which both participants and researchers know the medication being dosed — designed to assess the efficacy and safety of Crexont in people with advanced Parkinson’s and motor fluctuations. Unlike previous trials, ADIP allows for dosing intervals to be adjusted to individual patient needs, which is expected to enhance symptom control. Participants will receive the treatment for 12 weeks, or about three months, with the option to receive the treatment for an additional three months.
With [the clinical trial] ADIP we aim to demonstrate the potential of [Crexont] to become a core therapy for people with [Parkinson’s] and moderate to severe motor fluctuations.
The trial’s main goal is to evaluate Crexton’s effectiveness compared with immediate-release CD/LD in improving on time relative to dosing interval and dosing frequency. Secondary objectives include assessing Crexont’s effectiveness in reducing off time and the safety of different Crexont dosing frequencies compared with immediate-release CD/LD.
“We recognise the substantial need for new treatment options, and with ADIP we aim to demonstrate the potential of [Crexont] to become a core therapy for people with [Parkinson’s] and moderate to severe motor fluctuations,” Knecht said.
Frank Weber, MD, Zambon’s CEO, added, “We believe CREXONT could represent a valuable therapeutic option in Europe to improve the lives of moderate to severe Parkinson patients.”
Zambon has entered into an exclusive agreement with Amneal Pharmaceuticals for the rights to seek approval and commercialize Crexont in the European Union, the U.K., and Switzerland.
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