Three clasped hands rest on a bed near a stethoscopeShare on Pinterest
Researchers hope a cough medicine used in Europe can be used to help slow the progression of Parkinson’s disease. Visoot Uthairam/Getty Images
  • Scientists report that the cough medication ambroxol showed promise in slowing the progression of Parkinson’s disease in a phase 2 clinical trial.
  • A phase 3 clinical trial is now getting underway.
  • Ambroxol has not been approved for use in the United States, but it is widely used as a cough medicine in Europe.

Scientists continue to look at the potential benefits of the cough medication ambroxol to help treat Parkinson’s disease.

The Cure Parkinsons organization in the United Kingdom along with VanAndel Institute are currently recruiting 330 people for a phase 3 clinical trial of ambroxol as a potential drug for slowing or stopping the progression of Parkinson’s disease.

The participants will take ambroxol or a placebo for two years. Researchers will measure the quality of life and movements as determining factors.

“This is a very intriguing area of research that may eventually lead us closer to personalized medicine,” said Dr. Melita Petrossian, a neurologist and director of the Movement Disorders Center at Providence Saint John’s Health Center in California.

“Today, Parkinson’s disease is treated with a ‘one-size-fits-all’ approach where medical professionals advise patients on the importance of exercise, Mediterranean diet, and medication options that address the loss of dopamine in the brain, such as levodopa, amantadine, and dopamine agonists,” Petrossian told Healthline.

“Though there is good evidence that exercise and diet are associated with a lower rate of progression of [Parkinson’s], the available medications do not slow progression and only treat the symptoms of the disease. Better treatments are sorely needed to prevent the progression of [the disease],” she added.

The success of a recent phase two clinical trial led to the upcoming phase three trial.

The results of the phase two trial that tested safety and tolerability were published in 2020. Researchers reported that ambroxol could slow the disease by increasing glucocerebrosidase levels in cells. This chemical promotes the effective removal of waste proteins in cells.

Ambroxol is an over-the-counter medicine used to reduce mucus in respiratory diseases. It is not approved by the Food and Drug Administration for use in the United States, but it is available and widely used as a cough medicine in Europe.

While the phase 2 trial showed the potential for slowing the progression of Parkinson’s disease, the primary purpose of the trial was to test the safety of the drug.

For the study, the dose of ambroxol was about 10 times higher than when taken as a cough medicine and was taken longer than its license allowed.

Parkinson’s disease is a brain disorder that causes unintended or uncontrollable movements, according to the National Institute on Aging.

“No one knows how it starts,” said Dr. Pietro Mazzoni, an associate professor of neurology and co-director at the Movement Disorders Division at The Ohio State University’s Wexner Medical Center.

“There is a very likely role of genetic factors and a possible role of environmental factors, but we don’t know the initial process that starts the brain changes caused by [Parkinson’s],” Mazzoni told Healthline. “These brain changes consist of gradual ill health and eventual death of neurons that produce the neurotransmitter dopamine in brain circuits that use dopamine to guide our movements. For example, a certain amount of dopamine usually determines how rapidly you walk and make other movements. When dopamine levels fall, walking and other movements become slower.”

Symptoms include:

  • Tremors in the hands, arms, legs, jaw, or head
  • Muscle stiffness
  • Slowness of movement
  • Impaired balance and coordination
  • Depression and other emotional changes
  • Difficulty swallowing, chewing, or speaking
  • Urinary problems or constipation
  • Skin problems
  • Sleep problems
  • Memory issues
  • Fatigue

Because symptoms appear gradually, it can be hard to know when to seek treatment.

A family member often notices physical or behavioral differences, Mazzoni said. For example:

  • Slowing of gait can appear as falling behind when walking with a spouse.
  • Others can perceive reduced facial expressiveness as becoming grumpy or sad, or apathetic.
  • Softening of voice volume could lead to frustrating exchanges between spouses.
  • Sense of unsteadiness and stumbling on low obstacles like a curb.
  • Handwriting becoming small or looking like chicken scratch.
  • Low energy.

Before symptoms appear, some people experience sleep difficulties, restless legs, constipation, and loss of smell.

The most significant risk factor for Parkinson’s disease is age. Most people develop it past age 60, but about 5 to 10 percent have early onset – before age 50. Early onset is often inherited.

Treatment for Parkinson’s disease varies depending on the person and their symptoms. However, there are some general approaches.

“Exercise of varying forms, the Mediterranean diet, good quality and quantity of sleep, social engagement, and management of depression and anxiety are all associated with slowing the progression of [Parkinson’s] and improving quality of life,” Petrossian said.

“Aside from medications such as levodopa, amantadine, dopamine agonists, and MAO-B inhibitors, surgical treatments include deep brain stimulation surgery and focused ultrasound. Physical, occupational, and speech therapy are also key to management,” she added.

“The missing piece of the puzzle is a medication to slow progression, so if ambroxol can do so, it would be a major global breakthrough,” Petrossian noted.