Understanding Levodopa in Parkinson's Disease: Why Timing and Medication Management Matter

Parkinson's disease affects more than 200,000 Australians and is one of the most common neurological conditions, particularly in older adults. While there is currently no cure, medications can significantly improve quality of life by helping to manage symptoms and maintain independence.

For people living with Parkinson's disease, understanding how their medications work—and taking them correctly—is essential. This is where a Home Medicines Review (HMR) can make a real difference.

What is Parkinson's disease?

Parkinson's disease is a progressive neurological condition caused by the gradual loss of nerve cells that produce dopamine, a chemical messenger that helps control movement. Symptoms typically appear only after a significant number of these dopamine-producing cells have been lost.

Common symptoms include:

• Tremor (shaking)

• Slowness of movement

• Muscle stiffness

• Poor balance and increased falls risk

• Shuffling gait

• Soft or monotone speech

• Small handwriting

• Constipation

• Difficulty swallowing

• Urinary symptoms

• Depression and anxiety

As Parkinson's progresses, symptoms often become more complex and medication regimens may require ongoing adjustment.

Why can't people simply take dopamine?

Although Parkinson's disease results from low dopamine levels in the brain, dopamine itself cannot be taken as a medication because it cannot cross the blood-brain barrier—a protective filter that prevents many substances in the bloodstream from entering the brain.

Instead, treatment relies on levodopa, a medication that can cross into the brain where it is converted into dopamine.

Why is levodopa combined with carbidopa or benserazide?

Levodopa is almost always prescribed together with either carbidopa or benserazide.

These medications prevent levodopa from being converted into dopamine before it reaches the brain. This has two major benefits:

• More levodopa reaches the brain where it is needed.

• Side effects such as nausea, vomiting and low blood pressure are reduced.

Without one of these medicines, only a very small amount of levodopa would reach the brain, making treatment much less effective.

Why is medication timing so important?

One of the unique challenges of Parkinson's disease is that medication timing is critical.

Levodopa works best when taken consistently and at the prescribed times. Delayed or missed doses can lead to a return of Parkinson's symptoms, including increased stiffness, slower movement and difficulty walking.

Many people also find that high-protein meals interfere with levodopa absorption. For this reason, it is often recommend taking levodopa around 30 minutes before meals or one hour after eating, where practical and appropriate.

Even small changes in medication timing can have a noticeable impact on symptom control.

What happens over time?

Levodopa is considered the most effective medication for improving the motor symptoms of Parkinson's disease. However, Parkinson's continues to progress despite treatment.

Over several years, many people experience:

• Shorter duration of symptom relief after each dose

• "Wearing off" before the next scheduled dose

• Fluctuations between good and poor mobility

• Involuntary movements known as dyskinesias

These changes are common and often require careful adjustment of medication doses, timing or additional therapies.

How can a Home Medicines Review help?

As Parkinson's progresses, medication regimens often become more complicated. A Home Medicines Review (HMR), conducted by an Accredited Pharmacist in collaboration with your GP, provides an opportunity to optimize treatment and improve medication safety.

During an HMR, your pharmacist may review:

• Whether medications are being taken at the correct times

• Medicines that may worsen Parkinson's symptoms

• Side effects such as dizziness, nausea or excessive sleepiness

• Strategies to improve adherence when multiple daily doses are required

• Potential drug interactions

• Swallowing difficulties that may affect medication administration

• Whether constipation, falls risk or other medication-related problems are being adequately managed

• 
  

The pharmacist can then provide recommendations to your GP to help ensure your Parkinson's treatment remains as effective and safe as possible.

If you or someone you care for is living with Parkinson's disease and taking multiple medications, ask your GP whether a Home Medicines Review may be appropriate. An Accredited Pharmacist can help identify opportunities to optimize therapy, improve medication safety and support ongoing independence.