In an 85‑year‑old patient with Parkinson disease, which of the following medications—bupropion hydrochloride sustained‑release 100 mg daily, apixaban (Eliquis) 5 mg twice daily, fluoxetine 10 mg daily, fluoxetine 20 mg daily, gabapentin 300 mg twice daily, midodrine 2.5 mg twice daily, ropinirole 5 mg (half tablet) nightly, and simvastatin 20 mg daily—could be contributing to constipation?

Medications Contributing to Constipation in This Parkinson's Patient

Multiple medications in this regimen are likely contributing to constipation: ropinirole (dopamine agonist), fluoxetine (SSRI), bupropion, and gabapentin all have constipating effects, with ropinirole being particularly problematic in Parkinson's disease patients.

Primary Culprits

Ropinirole (Parkinson's Medication)

• Dopamine agonists are specifically identified as causing constipation as a side effect in PD patients 1
• Constipation is the most frequent non-motor symptom in PD, and dopamine agonists like ropinirole directly exacerbate this 1
• The ESPEN neurology guidelines explicitly state that "certain PD medications (mainly dopamine agonists and anticholinergics)" contribute to constipation 1

Fluoxetine (30 mg total daily dose: 10 mg + 20 mg)

• SSRIs, while less constipating than tricyclic antidepressants, are still associated with constipation 2
• The 2025 systematic review notes that "selective serotonin reuptake inhibitors and serotonin-norepinephrine reuptake inhibitors offer alternatives" to tricyclics but still carry constipation risk 2
• At this combined 30 mg daily dose, constipation effects are clinically relevant

Bupropion SR

• FDA labeling explicitly lists constipation as a common side effect 3
• The drug label states: "The most common side effects of bupropion hydrochloride extended-release tablets (XL) include...constipation" 3

Gabapentin

• While not as prominently featured in the guidelines, gabapentin can reduce GI motility and contribute to constipation, particularly at the 600 mg daily dose this patient receives

Medications NOT Contributing to Constipation

• Apixaban (Eliquis): No significant GI motility effects
• Midodrine: Primarily affects blood pressure; not associated with constipation
• Simvastatin: Not a constipating agent

Clinical Context in Parkinson's Disease

The constipation in this patient is multifactorial:

1. Parkinson's disease itself causes constipation through enteric nervous system degeneration 1
2. Reduced physical activity from motor impairment compounds the problem 1
3. Multiple constipating medications create an additive effect

Management Approach

According to ESPEN guidelines for PD patients with constipation 1:

• First-line: Discontinue non-essential constipating medications 4
• Consider whether the dual fluoxetine dosing (10 mg + 20 mg = 30 mg total) could be consolidated or reduced
• Evaluate if bupropion is essential or if alternative antidepressants with less GI impact could be substituted
• Prophylactic treatment: Fermented milk with probiotics and prebiotic fiber, plus increased water and fiber intake 1
• Pharmacologic: Stimulant laxatives (bisacodyl) should be used routinely, as lifestyle modifications alone are insufficient 4

Critical Pitfall

Do not assume constipation is solely from Parkinson's disease when multiple constipating medications are present. The palliative care guidelines emphasize: "Providers should discontinue any nonessential constipating medications" 4. In this 85-year-old patient, medication rationalization is essential before escalating laxative therapy.