What medications are recommended for a patient with dry mouth (xerostomia), considering potential side effects and the patient's medical history, including glaucoma?

Medications for Dry Mouth (Xerostomia)

Start with non-pharmacological stimulation (sugar-free candies, lozenges, or chewing gum) for mild dry mouth, escalate to pilocarpine 5 mg four times daily for moderate dysfunction, and reserve saliva substitutes for patients with no residual salivary output. 1

Treatment Algorithm Based on Salivary Gland Function

Step 1: Assess Residual Salivary Function

• Measure whole salivary flow rates before initiating therapy to determine which treatment approach will be effective 1
• Rule out unrelated conditions such as candidiasis or burning mouth syndrome 1

Step 2: Mild Glandular Dysfunction (First-Line)

Non-pharmacological stimulation is the preferred initial approach:

• Sugar-free acidic candies or lozenges 1, 2
• Sugar-free chewing gum (xylitol-containing) 1, 2
• These work by stimulating residual glandular function mechanically and through taste 1

Step 3: Moderate Glandular Dysfunction (Second-Line)

Pharmacological stimulation with muscarinic agonists:

Pilocarpine (Preferred - Worldwide Availability)

• Dosing: 5 mg orally four times daily (20 mg/day total) 1, 3
• FDA-approved for dry mouth from Sjögren's syndrome and radiation therapy 3
• Increases salivary flow 2-3 fold compared to placebo 2
• Shows greater improvement in dry mouth than dry eye symptoms 2
• Most common adverse effect: Excessive sweating (>40% of patients) 1, 4, 3
• Approximately 2% discontinue due to side effects, primarily sweating 1, 2

Cevimeline (Alternative)

• May have fewer systemic adverse effects than pilocarpine 1
• Better tolerance profile in retrospective comparisons 1
• Not as widely available worldwide as pilocarpine 1
• Requires residual salivary gland function to be effective 4

Step 4: Severe Dysfunction (No Salivary Output)

Saliva substitution is the preferred approach:

• Use oral sprays, gels, or rinses containing methylcellulose or hyaluronate 1
• Products should have neutral pH and contain fluoride and electrolytes to mimic natural saliva 1
• Oxygenated glycerol triester (OGT) spray shows evidence of effectiveness over electrolyte sprays (approximately 2-point improvement on 10-point scale) 5

Critical Contraindication: Glaucoma

Pilocarpine and cevimeline are contraindicated in patients with uncontrolled narrow-angle glaucoma due to their muscarinic effects causing pupillary constriction and potential angle closure. If the patient has controlled glaucoma or wide-angle glaucoma, use with extreme caution and close ophthalmologic monitoring.

Special Populations and Monitoring

Geriatric Patients

• Monitor closely for adverse effects, particularly in those with multiple comorbidities 4
• No dose reduction required based on age alone 4

Patients with Dementia

• Use cevimeline with caution due to potential cholinergic effects on cognition 4

Respiratory Disease

• Use muscarinic agonists with caution in asthma or COPD due to potential bronchoconstriction 4, 6

Renal or Hepatic Impairment

• Exercise clinical judgment and monitor for adverse effects, as no specific dose adjustment guidelines exist 4

Common Pitfalls to Avoid

• Do not prescribe muscarinic agonists to patients with complete glandular destruction - they require residual salivary function to work 4
• Do not overlook medication-induced xerostomia - review and consider reducing or changing xerogenic medications (anticholinergics, antihistamines, diuretics) before adding new treatments 6, 7
• Do not use pilocarpine in uncontrolled glaucoma - this is an absolute contraindication
• Do not expect equal efficacy for dry eye and dry mouth - pilocarpine shows greater improvement in oral symptoms than ocular symptoms at standard dosing 2, 3

Evidence Quality Note

The 2020 EULAR guidelines 1 acknowledge that evidence for muscarinic agonists in primary Sjögren's syndrome is limited, with an unfavorable safety profile, which is why they recommend trying non-pharmacological approaches first. However, FDA-approved pilocarpine remains the standard pharmacological option when non-pharmacological measures fail 3.