In late February 2020, Parkinson Canada offered a webinar on drug therapy in Parkinson’s disease (PD), featuring speaker Greta Mah, a clinical pharmacist in Canada. She provided a general overview of medications used in PD within the US as well as in Canada, describing the main categories of drug therapy often used in PD, which may be a helpful refresher for some readers. We at Stanford Parkinson’s Community Outreach listened to the webinar and are sharing our notes.  

Note: Dr. Mah spent some of the webinar discussing updates to the Canadian clinical practice guidelines for PD, which is not relevant for our US-based audience. We have not included those updates in this summary.

The webinar was recorded and may be uploaded to Parkinson Canada’s YouTube channel, though it was not yet available as of this writing.

For additional terrific resources on PD medications – including downloadable guides, links to online resources, and webinars and podcasts – see this page on the Stanford Parkinson’s Community Outreach website.

Now… on to our notes from the webinar.

– Lauren

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Drug Therapy for Parkinson’s Disease – Webinar notes

Presented by Parkinson Canada

February 19, 2020

Summary by Lauren Stroshane, Stanford Parkinson’s Community Outreach

Note: Dr. Mah spent some of the webinar discussing updates to the Canadian clinical practice guidelines for PD, which is not relevant for our US-based audience. We have not included those updates in this summary.

Once people have been diagnosed with Parkinson’s disease (PD), health care providers should encourage them to participate in their own care and be active partners in their own health decisions. While PD is a progressive disease, there are lots of treatments available, and tremendous amounts of ongoing research. New therapies are available, such as Duopa (levodopa intestinal gel) and safinamide (an oral medication). An inhaled version of levodopa, Inbrija, was approved a year ago for management of acute “off” periods.

Vitamins and supplements for PD generally do not provide much benefit according to research, but they are unlikely to be harmful. Dr. Mah cautioned against spending large amounts of money on substances such as Vitamin E and Coenzyme Q10 (CoQ-10), which can be very expensive and do not have evidence to support their use. If a person is tested and found to be deficient in a vitamin, such as Vitamins D or B12, then it is important to get more of these substances. Most nutritionists recommend oral supplementation but also trying to eat more foods containing these vitamins. For those who experience unintentional weight loss, nutritional supplements such as protein powder may be beneficial.

Exercise remains an essential component in managing PD, in addition to any oral treatments.

When should a person consider starting drug therapy for PD?

Every individual is different. Typically, a neurologist will recommend starting medication when symptoms have become bothersome or prevent normal function. Motor issues such as tremor or stiffness in the dominant hand tend to accelerate the need for medication. Those who feel social embarrassment due to their symptoms may also wish to try medication sooner. Whether an individual is retired or continuing to work is another factor, as well as whether their hobbies, exercise, and other activities are being impacted by PD symptoms. Lastly, cost and insurance coverage can be significant factors in the decision of when to start medication – and which medications to try.

Please note that all medications are referred to by their generic name, with the most widely familiar brand name in parentheses.

What are the main medications used for PD?

All medications used for PD are intended to make more dopamine available to the brain. The main classes of drugs that are used include monoamine oxidase inhibitors type B (MAO-B); levodopa, available in various formulations; and dopamine agonists. An older class of medications called anticholinergics is rarely used nowadays. Each of these drug types will be explained in more detail below.

Monoamine oxidase inhibitors, type B (MAO-B)

This drug type retains dopamine by preventing the usual breakdown of the molecule, extending the amount of dopamine available to the brain. They are the least potent of all the medications used for PD, but can provide some benefit for milder symptoms or as an adjunct with other PD drugs. Rasagiline generally causes fewer side effects, but it is often expensive. Sometimes insurance will require that a person try its cheaper cousin, selegiline, before it will agree to cover rasagiline. These medications may cause sleep issues if taken at night, and for that reason patients are advised to take their daily dose in the morning.

Levodopa

Used in many different formulations along with carbidopa, levodopa – also known as Sinemet, Rytary, and Duopa, among others – is the only drug that converts to actual dopamine in the brain. Levodopa often causes nausea or gastrointestinal upset when first starting to take it; usually by starting at a tiny dose and gradually increasing, most people are eventually able to tolerate a sufficient dose of levodopa. It is usually combined with carbidopa to decrease the number of side effects and help the drug absorb better. Carbidopa-levodopa is considered the “gold standard” in PD treatment, as it is the most effective of all the medications.

Over time, as PD progresses, motor fluctuations – rapid, unpredictable changes in motor symptoms – often begin to occur, with early wearing off of levodopa doses. This can be frustrating and disabling, but can often be managed with the addition of other medications and changes in dose schedule. Dyskinesias –uncontrolled writhing movements of the limbs – sometimes are triggered by levodopa kicking in or wearing off. These movements can be bothersome, if severe, but many people do not notice them.

Dopamine agonists

Dopamine agonists work by mimicking dopamine to the brain. Examples include pramipexole (Mirapex); ropinirole (Requip); and rotigotine (Neupro), which is available as a patch. Mirapex and Requip also have long-acting versions available, though these are not always covered by insurance.

These medications can be effective for PD symptoms and tend to be associated with less motor fluctuations. However, they can also cause serious side effects, particularly in those over the age of 65. For this reason, they are typically only prescribed for younger patients. Side effects can include impulse control disorders, which can manifest as compulsive behaviors such as gambling, shopping, and hypersexuality.

Other medications for PD

Anticholinergic medications have been around for a long time and are no longer used commonly for PD. In rare cases, they are sometimes used in younger patients with prominent tremor that does not respond adequately to other PD medications. Examples include benztropine (Cogentin) and trihexyphenidyl (Artane).

Amantadine is a unique medication that is sometimes used in PD. It was originally used for treating influenza type A, but was found to be helpful for dyskinesias in PD.

Most patients with significant PD symptoms are on a combination of multiple medications to help provide the best on-time and overall function.