Infusion & Device-Based Therapies for Parkinson's Disease

When oral dopaminergic therapy can no longer adequately control motor fluctuations and deep brain stimulation is not feasible or preferred, infusion and device-based therapies offer continuous or near-continuous dopaminergic stimulation to stabilize plasma levodopa levels and reduce the peaks and troughs that drive wearing off and dyskinesia. This article reviews the three established infusion platforms — levodopa-carbidopa intestinal gel (LCIG), subcutaneous foslevodopa-foscarbidopa (Vyalev), and continuous subcutaneous apomorphine infusion (CSAI) — along with the on-demand rescue devices covered briefly in the Motor Complications article.

When to Consider Advanced Therapies

Recognizing the right time to transition from oral to device-based therapy is a key clinical skill. The OBSERVE-PD study found that ~50% of advanced PD patients meeting criteria for device-aided therapy were not being referred. Practical screening criteria:

• "5-2-1" rule: ≥5 doses of oral levodopa/day AND ≥2 hours of OFF time/day AND ≥1 hour of troublesome dyskinesia/day
• Significant impact of motor fluctuations on daily activities, employment, or quality of life despite optimized oral therapy (including adjuncts, rescue agents, and ER formulations)
• Non-motor fluctuations (anxiety, pain, mood swings) tracking with OFF state
• Gastroparesis causing erratic levodopa absorption and unpredictable motor response

Levodopa-Carbidopa Intestinal Gel (LCIG)

Mechanism & Delivery

• LCIG (Duopa in US, Duodopa in EU) is a stable gel suspension of levodopa (20 mg/mL) and carbidopa (5 mg/mL) delivered directly into the proximal jejunum
• Delivered via a PEG-J tube (percutaneous endoscopic gastrojejunostomy) connected to a portable infusion pump worn in a belt/holster
• Bypasses the stomach → eliminates the influence of gastric emptying on levodopa absorption → achieves stable plasma levodopa levels
• Typically infused for 16 hours/day (waking hours) with optional oral CD/LD at night
• Dose components: morning bolus (rapid ON) + continuous maintenance dose + patient-activated extra doses for breakthrough OFF

Efficacy

• Pivotal double-blind RCT (Olanow et al., 2014): 71 patients, LCIG vs oral CD/LD, 12 weeks. OFF time reduced by −4.04 hours with LCIG vs −2.14 with oral (difference −1.91 h, P=0.0015). ON time without troublesome dyskinesia increased by +4.11 vs +2.24 hours (P=0.0059)
• DYSCOVER (Phase 3b, 2020): LCIG significantly reduced dyskinesia vs optimized medical therapy (UDysRS change: −17.4 vs −2.3, difference −15.1; P<0.001)
• DUOGLOBE (real-world, 3-year): Sustained OFF time reduction of −3.3 hours (P<0.001); improvements in dyskinesia, NMS, sleep, and QoL maintained through 36 months
• MDS EBM Review: rated "clinically useful" for treatment of motor fluctuations

Complications & Practical Considerations

• Device-related complications (~30%): Tube dislocation or kinking (most common — may cause sudden OFF), stoma-site infection, tube occlusion, peritonitis (rare), pump malfunction. These are the main reason for treatment discontinuation
• Polyneuropathy: Reported with long-term LCIG use, possibly related to vitamin B12 deficiency and elevated homocysteine from COMT-mediated levodopa metabolism. Monitor B12, methylmalonic acid, and homocysteine. Supplement prophylactically
• Weight loss: Common (multifactorial — reduced polypharmacy, altered absorption, advanced PD)
• PEG-J procedure: Requires endoscopy with sedation; typically preceded by a nasojejunal (NJ) test phase (3–7 days) to confirm efficacy and optimize dosing before permanent PEG-J placement
• Caregiver involvement: Many patients require caregiver assistance with daily tube connection, pump operation, and stoma care

Subcutaneous Foslevodopa-Foscarbidopa (Vyalev)

Mechanism & Delivery

• Foslevodopa (levodopa prodrug) and foscarbidopa (carbidopa prodrug) are highly water-soluble phosphorylated prodrugs that allow concentrated subcutaneous infusion — solving the solubility problem that previously prevented SC levodopa delivery
• Delivered via a small subcutaneous infusion pump with a single infusion site, changed every 72 hours
• Provides 24-hour continuous delivery (including overnight — unlike LCIG's typical 16-hour regimen), achieving steady-state levodopa levels with minimal fluctuation
• No abdominal surgery or intestinal tube required — a fundamental advantage over LCIG
• FDA-approved October 2024; previously approved in EU and Japan (as Produodopa)

Efficacy

• Phase 3 pivotal trial (Soileau et al., M15-736): 141 patients, double-blind, double-dummy, 12 weeks. SC foslevodopa-foscarbidopa vs oral IR CD/LD:
  • ON time without troublesome dyskinesia: +2.72 hours vs +0.97 hours (difference +1.75 h; 95% CI 0.46–3.05; P=0.0083)
  • OFF time: −2.75 hours vs −0.96 hours (difference −1.79 h; P=0.0054)
• 52-week open-label study (Aldred et al., M15-741): 244 patients; sustained improvement — ON time without troublesome dyskinesia improved by +3.8 hours, OFF time reduced by −3.5 hours. Morning akinesia prevalence dropped from 77.7% to 27.8%
• ROSSINI real-world study (MDS 2025): 6-month data confirmed sustained motor fluctuation improvement and acceptable safety in clinical practice

Complications & Practical Considerations

• Infusion site reactions: The most common adverse event — erythema (27%), pain (26%), cellulitis (19%), edema (12%). Most are mild to moderate. Site rotation and hygiene are essential
• Infusion site nodules: Subcutaneous nodules develop at infusion sites over time; can affect absorption
• Hallucinations and dyskinesia: More common than with oral CD/LD (from higher, more sustained levodopa exposure)
• 24-hour coverage: Continuous overnight infusion may improve sleep, morning akinesia, and nocturnal motor symptoms — a theoretical advantage over 16-hour LCIG
• Dose conversion: Total daily levodopa dose from oral therapy is converted to a continuous infusion rate; typical range 700–4250 mg levodopa equivalent over 24 hours
• No abdominal surgery: Initiation, optimization, and maintenance can be done in the outpatient clinic setting without hospitalization

Continuous Subcutaneous Apomorphine Infusion (CSAI)

Mechanism & Delivery

• Apomorphine is a potent, non-selective D1/D2 dopamine receptor agonist with rapid onset (SC: ~10 min) and short duration (~45–60 min for bolus)
• CSAI is delivered via a small ambulatory syringe-driver pump with a subcutaneous butterfly needle, typically for 12–18 hours/day (some patients use 24-hour infusion)
• Widely used in Europe, Australia, and parts of Asia for advanced PD motor complications; less common in the US where it has not been formally FDA-approved for continuous infusion (only intermittent SC injection [Apokyn] is FDA-approved)

Efficacy

• TOLEDO trial (Katzenschlager et al., 2018): First double-blind, placebo-controlled RCT of CSAI. 107 patients, 12 weeks. CSAI reduced OFF time by −2.47 hours vs −0.58 with placebo (P=0.0025). ON time without troublesome dyskinesia increased by +2.77 vs +0.80 hours (P=0.0005). However, a co-primary endpoint (CGI-I) failed to reach significance
• Open-label studies consistently show OFF time reductions of 3–5 hours/day, with 30–50% of patients able to reduce or discontinue oral levodopa ("apomorphine monotherapy")
• Improvement in dyskinesia is primarily through levodopa dose reduction rather than a direct antidyskinetic effect
• EAN/MDS-ES guidelines (2022): recommended for advanced PD motor fluctuations when oral therapy is insufficient

Complications & Practical Considerations

• Skin nodules: The most significant practical limitation — subcutaneous nodules at infusion sites occur in >70% of patients over time. Minimize with site rotation, dilute solutions, ultrasound-guided placement, and topical silicone patches
• Nausea: Very common at initiation; managed with domperidone (standard in Europe; not FDA-approved in US) or trimethobenzamide. Pre-treatment for 3 days before apomorphine start
• Neuropsychiatric effects: Hallucinations, confusion, impulse control disorders (a DA class effect). Higher risk than with levodopa-based infusion
• Orthostatic hypotension: Potent dopaminergic vasodilation
• Hemolytic anemia and injection site abscess: Rare but reported with long-term use
• Advantages: No surgery required, rapid onset, can be started and titrated quickly (even as inpatient), useful as bridge therapy before DBS or LCIG

Comparison of Advanced Therapies