Why does a patient with advanced Parkinson's disease (PD) have an intrajejunal levodopa/carbidopa infusion pump or a subcutaneous apomorphine pump?

Why Parkinson's Patients Use Infusion Pumps

A Parkinson's patient has a pump to deliver continuous medication (either subcutaneous apomorphine or intrajejunal levodopa/carbidopa) when they have advanced disease with severe motor fluctuations and "OFF" periods that cannot be controlled by oral medications alone.

Understanding the Clinical Context

Patients with advanced Parkinson's disease develop motor fluctuations and dyskinesias after years of oral levodopa therapy 1, 2. These motor complications are accompanied by non-motor symptoms and significantly impair quality of life 1. When oral medications fail to provide stable symptom control, continuous drug delivery via pump becomes necessary 3.

Two Main Pump Options

Subcutaneous Apomorphine Infusion

• Delivers apomorphine continuously under the skin to provide steady dopaminergic stimulation 4, 2
• Less invasive than other advanced therapies and is reversible 4
• Particularly effective for managing peak-effect dyskinesias and OFF-period non-motor symptoms 4
• Patients typically continue taking oral levodopa alongside the infusion 2
• The FDA-approved ONAPGO system delivers up to 98 mg per day via programmable pump with adjustable flow rates and extra bolus doses for breakthrough OFF episodes 5

Intrajejunal Levodopa/Carbidopa Infusion

• Delivers levodopa/carbidopa gel directly into the small intestine via a gastrostomy tube 1, 2
• More complex procedure requiring surgical placement of infusion tube 2
• Allows replacement of all oral medications with continuous delivery 2
• Shows particularly strong improvement in sleep/fatigue, gastrointestinal, urinary, and sexual non-motor symptoms compared to apomorphine 6

Why Pumps Work Better Than Pills

The fundamental problem is that oral medications cause erratic drug levels in the bloodstream, leading to unpredictable "ON" and "OFF" periods 3. Pumps provide continuous dopaminergic stimulation, which:

• Reduces the number and duration of OFF periods 3
• Improves motor function with large effect sizes (≥0.8) 6
• Enhances quality of life scores significantly 6
• Better controls both motor and non-motor symptoms 6

Patient Selection Criteria

Good Candidates for Apomorphine Pump

• Advanced PD with motor fluctuations not controlled by oral/transdermal medications 4
• Patients who want a less invasive, reversible option 4
• Advanced age is NOT a contraindication (unlike deep brain stimulation) 4

Contraindications for Apomorphine

• Severe dementia or neuropsychiatric symptoms 4
• Severe biphasic dyskinesias 4

Good Candidates for Levodopa/Carbidopa Intestinal Gel

• Advanced PD patients who can tolerate gastrostomy placement 1
• Those with prominent non-motor symptoms affecting sleep, GI function, or urinary/sexual function 6
• Patients willing to discontinue all oral PD medications 2

Important Limitations to Understand

Despite continuous delivery, OFF periods can still occur with pump therapy 3. This happens because:

• Changes in dopaminergic and non-dopaminergic mechanisms in the basal ganglia may render some symptoms unresponsive to dopaminergic therapy 3
• Device-related issues and site-specific drug delivery problems can occur 3
• The disease itself progresses beyond what dopamine replacement alone can manage 3

Practical Considerations

For Apomorphine Pumps

• Common side effect: skin nodules at infusion sites 6
• Requires patient training on pump operation and site rotation 5
• Pump must be programmed by trained healthcare provider 5
• Long-term compliance can be challenging 2

For Levodopa/Carbidopa Intestinal Gel

• Risk of peritonitis from gastrostomy 6
• More complex setup but potentially better long-term adherence 2
• Requires surgical procedure for tube placement 1

Comparative Effectiveness

In a multicenter observational study comparing both therapies, 75% of patients on intrajejunal levodopa improved in both quality of life and non-motor symptoms, while in the apomorphine group, a similar proportion improved in quality of life but only 40% improved in non-motor symptoms 6. Both therapies showed large effect sizes for motor symptoms, motor complications, and quality of life 6.

Common Pitfalls to Avoid

• Do not assume pumps eliminate all OFF periods—they reduce but don't completely prevent them in middle to late-stage disease 3
• Do not overlook the need for continued oral levodopa with apomorphine infusion in most cases 2
• Do not ignore nutritional considerations—patients on levodopa (including intestinal infusion) require monitoring of vitamin B status and homocysteine levels 7, 8