How to manage chronic cough in patients taking gabapentin?

Management of Chronic Cough in Patients Taking Gabapentin

Gabapentin is actually a recommended treatment option for unexplained chronic cough, not a cause of it, and can be used as a therapeutic trial for patients with chronic cough that remains unexplained after appropriate investigation. 1

Understanding Gabapentin's Role in Chronic Cough

Gabapentin is a neuromodulator that has been shown to be effective in treating unexplained chronic cough by addressing the central reflex sensitization that contributes to the cough mechanism. Rather than causing cough, gabapentin is recommended by the American College of Chest Physicians (CHEST) guidelines as a therapeutic option for patients with unexplained chronic cough.

Evidence Supporting Gabapentin for Chronic Cough

• A randomized, double-blind, placebo-controlled trial demonstrated that gabapentin significantly improved cough-specific quality of life compared to placebo in patients with refractory chronic cough 2
• The number needed to treat was 3.58, indicating substantial efficacy 2
• Gabapentin appears to work by addressing central reflex sensitization, which is a relevant mechanism in refractory chronic cough 2

Diagnostic Approach to Chronic Cough

Before considering gabapentin as a treatment:

1. Define unexplained chronic cough as a cough that persists longer than 8 weeks and remains unexplained after investigation and supervised therapeutic trials 1
2. Conduct a guideline/protocol-based assessment process that includes:
   • Objective testing for bronchial hyperresponsiveness
   • Testing for eosinophilic bronchitis
   • Consideration of a therapeutic corticosteroid trial 1

Treatment Algorithm for Chronic Cough

1. Rule out common causes of chronic cough:

   • Asthma
   • Eosinophilic bronchitis
   • GERD
   • Upper airway cough syndrome
   • Medication side effects (e.g., ACE inhibitors)

2. For patients with unexplained chronic cough after appropriate workup:

   • Consider a therapeutic trial of gabapentin 1
   • Consider multimodality speech pathology therapy 1

3. For patients with interstitial lung disease (ILD) and refractory cough:

   • Follow CHEST guidelines for unexplained chronic cough
   • Consider gabapentin and multimodality speech pathology therapy 1

Gabapentin Dosing Protocol

When prescribing gabapentin for chronic cough:

• Begin with 300 mg once daily
• Implement a dose escalation schedule, adding additional doses each day as tolerated
• Target a maximum tolerable daily dose of 1,800 mg in two divided doses 1
• Discuss potential side effects and risk-benefit profile before initiating treatment
• Reassess the risk-benefit profile at 6 months before continuing the medication 1

Monitoring and Side Effects

Common side effects of gabapentin reported in studies include:

• Nausea (31%)
• Fatigue (31%)
• Dizziness
• Dry mouth
• Confusion 2

Less common side effects include:

• Blurred vision
• Headache
• Memory loss 2

Special Considerations

Laryngeal Sensory Neuropathy

• Some patients with chronic cough may have underlying laryngeal sensory neuropathy involving the superior or recurrent laryngeal nerve 3
• Patients with vocal fold motion asymmetry (VFMA) on laryngoscopy may be more likely to respond to gabapentin treatment 4
• Consider laryngoscopic evaluation in patients with persistent cough to identify potential laryngeal neuropathy

Interstitial Lung Disease

For patients with ILD and chronic cough:

• Assess for progression of underlying ILD or complications from immunosuppressive treatment
• Consider further investigation/treatment according to guidelines for chronic cough
• For refractory cough, consider gabapentin as recommended in the CHEST guidelines 1

Clinical Pearls and Pitfalls

Pearls:

• Gabapentin has shown efficacy in treating chronic cough with a neurogenic component
• The presence of vocal fold motion asymmetry on laryngoscopy may predict better response to gabapentin 4
• Symptomatic relief has been achieved in 68% of patients with suspected sensory neuropathy of the laryngeal nerve 3

Pitfalls:

• Avoid prescribing proton pump inhibitors for unexplained chronic cough with a negative workup for acid gastroesophageal reflux disease 1
• Do not prescribe inhaled corticosteroids for unexplained chronic cough in patients with negative tests for bronchial hyperresponsiveness and eosinophilia 1
• Be aware that adverse effects may limit the gabapentin dose in approximately 25-44% of patients 4

By following this evidence-based approach, clinicians can effectively manage chronic cough in patients taking gabapentin or consider gabapentin as a treatment option for unexplained chronic cough.