Cough medicine can help treat Parkinson's disease
Ambroxol, an ingredient in common cough medicines, may be useful in treating Parkinson's disease.A landmark phase III clinical trial has begun in the United Kingdom. Scientists want to test whether a common cough medicine can be used to treat Parkinson's disease. Early studies showed that the drug, which was developed 50 years ago, could penetrate the brain and "cleanse" it of toxic proteins known to cause Parkinson's disease.
About a decade ago, researchers were studying new treatments for a condition known as Gaucher disease. This rare genetic disorder results in a deficiency of the enzyme glucocerebrosidase (or GCase). After testing hundreds of already-approved drugs, researchers found a common ingredient in various cough medicines called ambroxol that increases GCase activity.
Parkinson's disease researchers were interested in this. Low levels of GCase are associated with the pathology - this enzyme plays a crucial role in helping the brain clear toxic proteins.
Up to 15% of people with Parkinson's disease have a specific gene mutation that reduces GCase production. Also, many Parkinson's patients without the gene mutation still have unusually low levels of GCase. So the scientists decided to test whether ambroxol could work as a treatment for Parkinson's disease if it increased GCase activity.
Preclinical trials were promising, and it soon became clear that the drug could potentially help patients with Parkinson's disease. But two questions remained: whether the drug penetrated the blood-brain barrier enough in humans to work effectively, and whether patients could tolerate the doses needed for the drug to work.
A phase II trial in humans showed that ambroxol was safely tolerated at high enough doses to penetrate the brain and increase GCase levels. Also in 2020, ambroxol was found to reduce levels of the toxic protein alpha-synuclein in patients with Parkinson's disease and potentially improve their motor skills.
A phase III trial will begin this year in the United Kingdom. The study will enroll 330 patients with Parkinson's disease, and each participant will be offered either ambroxol or a placebo. The study will last two years.