What are the treatment options for constipation in Parkinson's disease?

Treatment Options for Constipation in Parkinson's Disease

Polyethylene glycol (PEG) is strongly recommended as the first-line pharmacological treatment for constipation in Parkinson's disease patients, with fiber supplements as supportive therapy. 1

Pathophysiology and Prevalence

Constipation is the most frequent non-motor gastrointestinal symptom in Parkinson's disease (PD), affecting a significant proportion of patients. It can precede motor symptoms by up to 20 years 2. The causes are multifactorial, including:

• Neurodegenerative processes affecting the enteric nervous system
• Side effects of PD medications (particularly dopamine agonists and anticholinergics)
• Reduced physical activity associated with motor impairment
• Pelvic floor dyssynergia 3

Treatment Algorithm

First-Line Therapies

1. Dietary Modifications:

   • Increase fluid intake 3
   • Add dietary fiber for patients with adequate fluid intake 3
   • Use fermented milk containing probiotics and prebiotic fiber 3
   • Psyllium (most effective fiber supplement) at >10g/day for at least 4 weeks 1

2. Pharmacological Treatment:

   • Polyethylene glycol (PEG): Strong recommendation with moderate evidence 3
     • Can be used alone or in combination with fiber supplements
     • Shows durable response over 6 months
     • Side effects include abdominal distension, loose stool, flatulence, and nausea

Second-Line Therapies

If first-line therapies fail, consider:

1. Stimulant Laxatives:

   • Bisacodyl 10-15 mg daily to TID 3
   • Goal: one non-forced bowel movement every 1-2 days
   • Can be used for short-term (4 weeks or less) or as rescue therapy

2. Osmotic Laxatives:

   • Magnesium oxide (conditional recommendation) 3
     • Start at lower dose and increase if necessary
     • Avoid in patients with renal insufficiency due to risk of hypermagnesemia
   • Lactulose (conditional recommendation for those who fail other therapies) 3
     • Be aware of common side effects: bloating and flatulence

Third-Line Therapies

For refractory constipation:

1. Prokinetic Agents:

   • Prucalopride (selective 5-HT4 receptor agonist) 4
     • Stimulates colonic peristalsis and increases bowel motility
     • Dosage: 1-2 mg once daily
     • Reduces colonic transit time by approximately 12 hours

2. For Opioid-Induced Constipation:

   • Methylnaltrexone 0.15 mg/kg subcutaneously every other day 3
   • Avoid in cases of mechanical bowel obstruction

Rescue Measures for Severe Constipation

• Glycerine suppository ± mineral oil retention enema 3
• Bisacodyl suppository (one rectally daily-BID) 3
• Manual disimpaction (if impacted) following pre-medication with analgesic ± anxiolytic 3
• Tap water enema until clear 3

Special Considerations

1. Rule out other causes of constipation:

   • Hypercalcemia, hypokalemia, hypothyroidism, diabetes mellitus 3
   • Medication side effects (antacids, anticholinergics, antidepressants, antispasmodics) 1
   • Impaction or mechanical obstruction 3

2. Pelvic floor dyssynergia:

   • Consider specialized treatments like biofeedback therapy 5

3. Impact on medication absorption:

   • Chronic constipation can delay gastric emptying and absorption of PD medications 6
   • Addressing constipation may improve response to PD medications

Monitoring and Follow-up

• Assess for treatment response with goal of one non-forced bowel movement every 1-2 days
• Monitor for side effects of treatments
• Adjust therapy based on symptom control and side effects
• Consider that reduced motor performance is associated with more severe constipation 7

Pitfalls and Caveats

• Avoid magnesium preparations in patients with renal insufficiency 3
• Be aware that phytotherapeutic agents like STW5 have not shown efficacy for PD-related constipation 8
• Recognize that constipation severity increases with age and disease progression 7
• Ensure adequate hydration when using fiber supplements to prevent worsening constipation 3

By following this algorithmic approach and selecting treatments based on individual patient factors and response, constipation in Parkinson's disease can be effectively managed to improve quality of life and potentially enhance the efficacy of PD medications.