What is the treatment for IgG4 (Immunoglobulin G4)-related dry mouth?

Treatment of IgG4-Related Dry Mouth

Corticosteroids are the first-line treatment for IgG4-related dry mouth, with prednisone at an initial dose of 40 mg daily (or 0.6-0.8 mg/kg daily) for 4 weeks, followed by a gradual taper over 2-3 months. 1

Initial Management Approach

First-Line Treatment

• Corticosteroid therapy:
  • Initial dose: Prednisone 40 mg daily (or 0.6-0.8 mg/kg daily) for 4 weeks 1
  • Taper schedule: Gradually reduce over 2-3 months to maintenance dose of 2.5-5 mg/day 2
  • Duration: Maintenance therapy is typically continued for up to 3 years in Japan, but cessation should be attempted within this timeframe to minimize steroid-related complications 2

Supportive Measures (to be used alongside corticosteroids)

• Dietary modifications:

  • Improve hydration and limit caffeine intake 1
  • Avoid crunchy, spicy, acidic, or hot foods/drinks 1
  • Avoid alcohol-containing mouthwashes 3

• Topical measures:

  • Saliva substitutes and moisture-preserving mouth rinses 1
  • Sugar-free chewing gum, lozenges, or candy to stimulate saliva production 1
  • Water sips throughout the day 1

• Systemic sialagogues (for moderate to severe symptoms):

  • Cevimeline (30 mg three times daily) or pilocarpine (5 mg three to four times daily) 1

Management of Relapse or Refractory Disease

Second-Line Treatment

• Immunomodulatory agents for steroid-dependent or relapsing disease:
  • Azathioprine (2 mg/kg/day) 1, 4
  • Mycophenolate mofetil 1
  • 6-mercaptopurine 1

Third-Line Treatment

• Rituximab (anti-CD20 monoclonal antibody):
  • Dosing: Two infusions of 1,000 mg, 15 days apart 5
  • Particularly effective for patients who fail to respond to immunomodulatory drugs 2
  • May be administered every 6 months for maintenance 1
  • Leads to prompt clinical improvement in refractory IgG4-RD with active inflammation 5

Monitoring and Follow-up

• Assess clinical response through symptom improvement and ability to taper steroids 1
• Monitor serum IgG4 levels as a marker of disease activity 5
• Regular dental check-ups to prevent dental caries and maintain oral health 1
• Evaluate for relapse during steroid tapering or after withdrawal (occurs in approximately 30% of patients) 1

Special Considerations

• For elderly patients or those with contraindications to high-dose steroids (e.g., insulin-dependent diabetes, severe osteoporosis), lower initial doses of prednisone (10-20 mg daily) may be considered 1
• Patients with IgG4-related disease affecting multiple organs should be referred to specialists with experience in managing this condition 1
• Dental referral is essential for patients with severe dry mouth to prevent dental caries 1

Common Pitfalls and Caveats

• Failure to distinguish IgG4-related disease from malignancy or other similar conditions can lead to inappropriate therapy or unnecessary surgery 2
• Relapse is common (approximately 30%) during steroid tapering or after withdrawal 1
• Long-term corticosteroid therapy can lead to significant side effects, necessitating steroid-sparing agents 1
• Involvement of multiple organs may require a multidisciplinary approach 1
• Advanced fibrosis may lead to poor response to medical treatment 1

By following this treatment algorithm, most patients with IgG4-related dry mouth can achieve significant improvement in symptoms and quality of life, though long-term management is often required due to the chronic nature of the disease.