Ambroxol to Slow Progression in Parkinson Disease (ASPro-PD): A Phase IIIA multi-centre randomised placebo-controlled trial

A daily dose of ambroxol—a common cough medicine—is being tested to see if it can slow the relentless progression of Parkinson’s disease. This matters because Parkinson’s currently has no treatment that modifies the underlying disease course. Existing drugs manage symptoms temporarily but do not stop the gradual loss of dopamine-producing neurons. The trial builds on earlier evidence that ambroxol can cross the blood-brain barrier and boost the activity of a cellular cleanup enzyme called glucocerebrosidase, which is often impaired in Parkinson’s patients. If the drug works, it would be the first therapy to target a core biological driver of the disease rather than just masking its effects. If successful, this research could change how Parkinson’s is managed—turning a relentlessly progressive condition into one that can be slowed, buying patients years of better mobility, cognition, and independence. That would reduce the burden on carers and the NHS, and shift the focus of Parkinson’s care from symptom control to disease modification. Even if the trial shows only a modest slowing of progression, it would validate a new therapeutic pathway and open the door to repurposing other existing drugs for neurodegenerative diseases.