Parkinson’s disease (PD) is a progressive neurodegenerative disorder affecting over 1 million people in North America. As PD progresses, decreased dopamine production leads to growing movement and motor control challenges. While there is currently no cure, medication can help manage symptoms.

This article provides an educational overview of the main PD drug types, mechanisms of action, benefits, and potential side effects.

Dopaminergic Medications: The Cornerstone of PD Treatment

The primary goal of PD drugs is to replace lost dopamine activity by:

  • Providing dopamine precursors that convert to dopamine in the brain
  • Mimicking dopamine effects at brain receptors
  • Preventing the breakdown of dopamine

Levodopa

Levodopa, which crosses the blood-brain barrier and converts to dopamine, has been the gold standard PD treatment for decades. While very effective at managing movement symptoms, long-term use of levodopa is linked with side effects like dyskinesias.

Dopamine Agonists

Dopamine agonists directly activate dopamine receptors, often used early on to delay starting levodopa. This may reduce later complication risks. Dopamine agonists like pramipexole (Mirapex) help control motor symptoms but have side effects like sleepiness and confusion.

Enzyme Inhibitors

Drugs like selegiline inhibit enzymes that metabolize dopamine, leaving more active dopamine available in the brain. Used alone early on or combined with levodopa later to allow lower doses.

Preserving Dopamine Levels With Enzyme Inhibitors

A unique approach to managing Parkinson’s involves targeting enzymes that break down dopamine in the brain.

Monoamine oxidase B (MAO-B) inhibitors block the MAO-B enzyme, reducing dopamine metabolism. This leaves more dopamine available to stimulate movement-related brain areas.

Common MAO-B inhibitors like selegiline (Deprenyl/Eldepryl) and rasagiline (Azilect) can provide mild to moderate symptom relief, especially early on. The recently approved safinamide (Xadago) offers similar benefits.

While not as powerful as dopamine replacement, they have relatively few side effects like gastrointestinal discomfort or insomnia. Later in PD, they may supplement levodopa.

Another player in dopamine breakdown is the COMT enzyme, inhibited by drugs like entacapone (Comtan). COMT inhibitors extend levodopa’s effects by slowing its metabolism. They are primarily used with levodopa rather than alone.

Targeting Dopamine Receptors With Agonist

Instead of introducing extra dopamine-like levodopa, dopamine agonists stimulate dopamine receptors directly. First introduced in the 1970s, these drugs act at brain receptors similarly to how dopamine would.

Dopamine agonists like pramipexole (Mirapex), ropinirole (Requip), and rotigotine patches (Neupro) can reduce motor symptoms, especially early on. This spares patients some levodopa side effects in the near term. They may cause dizziness, hallucinations, swelling, or sleep disorders.

While agonists aren’t as potent, starting with low doses combined with levodopa or MAO-B inhibitors may balance symptom control with side effect risks. This highlights the importance of tailoring drug regimens to each Parkinson’s patient’s changing needs.

Additional Drug Options

Additional Drug Options - Safe Therapeutics

While regulating dopamine levels is central, other drug classes like anticholinergics or amantadine can also provide benefits in managing specific Parkinson’s symptoms.

Conclusion

A range of medication options exist for managing Parkinson’s, from replacing lost dopamine to preventing its breakdown.

Understanding drug types, uses, and side effects allows patients to make informed choices, balancing symptom control and quality of life. Close doctor-patient communication ensures treatments adapt appropriately throughout this complex disease.

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