What Drug May Allow Michael J. Fox To Act Again?

Several news outlets are reporting today that actor Michael J. Fox may be returning to network television next year.

The 51-year-old, known for his work on the TV series Family Ties and Spin City, as well as his film role as Marty McFly in the Back to the Future trilogy, stopped working in 2000 due to worsening symptoms of Parkinson’s Disease. In the past few years, he has made guest appearances on Rescue Me, Curb Your Enthusiasm, and The Good Wife.

In May, Fox told ABC News‘ Diane Sawyer that changes in his medication have improved his symptoms, in particular his movement problem called dyskinesia (see below).

Now it seems that Sony Pictures Television is developing a sitcom for Fox for fall 2013. The company has reportedly also enlisted the talents of Will Gluck, director of the film Easy A and writer Sam Laybourne, whose credits include Cougar Town and Arrested Development.

Fox has been a strong advocate for Parkinson’s Disease research, having started the Michael J. Fox Foundation for Parkinson’s Research. Google co-founder, Sergey Brin, has a genetic risk of developing Parkinson’s Disease and works with the Fox Foundation.

What is Dyskinesia?

Dyskinesia is a movement disorder which includes the decreased ability to perform voluntary movements as well as the presence of involuntary movements, such as tics or chorea.

A tic is a sudden, repetitive, nonrhythmic motor movement or vocalization involving discrete muscle groups.

Chorea is characterized by brief, semi-directed, irregular movements that are not repetitive or rhythmic, but appear to flow from one muscle to the next, and are often described as “dance-like.”

Dyskinesia can be anything from a slight tremor of the hands to uncontrollable movement of, most commonly, the upper body but can also be seen in the lower extremities.

What medications are used to treat Parkinson’s Disease?

As we’ve outlined before, Parkinson’s Disease (PD) is caused by the loss of a chemical in the brain called dopamine. Dopamine allows for the smooth movement of muscles in the body.

Dopamine Replacement

In the 1970’s, the FDA approved Levodopa as the first medication to treat PD. Levodopa is converted by enzymes in the brain to dopamine. Levodopa remains the single most effective agent in the management of Parkinson’s symptoms.

Often it is combined with a levodopa enhancer called Carbidopa, which slows the breakdown of Levodopa. The combination is known as Sinemet. It is available in standard and controlled release preparations.

Although Levodopa significantly improves patient mobility, it does not slow disease progression.

What are the Common Side Effects?

• Nausea
• Vomiting
• Loss of appetite
• Lightheadedness
• Lowered blood pressure
• Confusion
• Dyskinesia

Dopamine Agonists (Pramipexole, Ropinerole, Bromocriptine)

Dopamine agonists are not converted into dopamine, but mimic the actions of dopamine on the brain. They can be used with Levodopa/Carbidopa.

They are less likely to cause dyskinesias than Levodopa/Carbidopa. They are also available in forms other than pills, such as a skin patch.

Like dopamine replacement drugs, they can not slow the progression of the disease.

Side effects include sleepiness, hallucinations and an increase in risk-taking behavior.

MAO-inhibitors (Brand names: Selegiline, Rasagilene)

MAO-inhibitors slow down an enzyme which breaks down Levodopa. This allows it to act for a longer period of time.

It can be used in combination with Sinemet. It may have a mild anti-depressive effects. Depression is common in PD.

Unfortunately it may have interactions with other drugs and foods.

Amantadine

Amantadine is an anti-virus drug used for treating the flu. When it was reported that a patient with PD’s symptoms decreased when she was put on Amantadine, and worsened when the medication was stopped, researchers began to study its use in other PD patients, a process known as drug repurposing.

Those studies showed that Amantadine reduces symptoms of fatigue, tremor, and bradykinesia (slow movements) in early Parkinson’s disease and may reduce dyskinesias in more advanced Parkinson’s disease.

Amantadine is one of the new medications that Michael J. Fox is taking.

Side effects of Amantadine may include GI discomfort, nausea, sleep disturbance, and nervousness. Chronic treatment with amantadine may result in a reddish-purple skin discoloration of the legs called livedo reticularis.