Xerostomia
Author: Gary M. Reisfield MD, Drew A. Rosielle MD, and George R. Wilson MD
Xerostomia (dry mouth) is a common symptom at the end of life — affecting more than 75% of hospice patients — and is a cause of significant morbidity and diminished quality of life. Salivary Functions include hydration, lubrication, and antimicrobial defense of the oral mucosa. Decreased salivation can lead to oral pain; accelerated dental morbidity; oral infections, fissures, and ulcerations; halitosis; alteration in taste and enjoyment of food; chewing and swallowing difficulties; nutritional impairment; trouble producing intelligible speech; and denture-related problems. Xerostomia is usually — although not always — associated with diminished salivary secretion (hyposialia).
Etiologies
- Medications with anticholinergic activity are the most common pharmacologic causes of xerostomia; these include many antiemetics, antihistamines, antipsychotics, antispasmodics, antidepressants (especially the tricyclics), and bronchodilators. Sympatholytics are also common culprits, including alpha-blockers (e.g. terazosin), alpha-2 agonists (e.g. clonidine), and beta-blockers (e.g. metoprolol). Medication-induced xerostomia may also result from direct interference with or damage to salivary tissue (as with some cancer chemotherapies). Opioids and benzodiazepines cause dry mouth, although the mechanisms are not known.
- Radiation for head and neck malignancies.
- Medical comorbidities such as HIV/AIDS, diabetes, renal failure, and Sjögren’s syndrome.
- Psychiatric comorbidities such as mood and anxiety disorders.
- Dehydration from any cause including drug-induced.
Treatment
- Address underlying causes. Eliminate unnecessary drugs or substitute less drying ones. If this is not feasible, titrate to lowest effective dose or modify dosing schedule. Replacing immediate-release with controlled-release formulations of some drugs may help (e.g. with oxybutynin and tolterodine for overactive bladder).
- Stimulate residual gland function.
- Sugarless gums and candies can stimulate salivary reflexes. Products containing vitamin C may reduce salivary viscosity.
- Cholinergic agonists such as pilocarpine and cevimeline. Therapeutic effect is rapid for drug-related xerostomia; latency is greater — often 8–12 weeks — for xerostomia related to radiotherapy. Pilocarpine is started at 5 mg po tid and can be titrated to 10 mg po tid. Cevimeline is dosed at 30 mg po tid. Urinary frequency, dizziness, and sweating are common side effects (and may be attenuated by administration with dairy products). These agents are contraindicated in asthma, acute iritis, and narrow-angle glaucoma, and should be used with caution in COPD and cardiac disease.
- Saliva substitutes. Most have limited efficacy; many patients find frequent sips of water more useful and convenient. Newer products with enzyme systems such as lactoperoxidase, lysozyme, and glucose oxidase (e.g. Biotène ® Oralbalance Dry Mouth Gel)—offer potential antimicrobial and moisturizing benefits. Due to limited duration of action, they may be particularly useful before eating, speaking, and sleeping. Recently, custom oral appliances with artificial saliva reservoirs have become available and may be particularly useful at night.
- Encourage oral hydration. Humidifiers, especially during sleep, may also be helpful.
- Optimize oral hygiene.
- Antimicrobial mouthwashes (alcohol-free). Chlorhexidine gluconate oral rinse, USP 0.12%, twice daily, may be effective in preventing dental caries and oral infections.
- Most toothpaste products contain the surfactant sodium lauryl sulfate (SLS), which can irritate dry mucosa and inactivate the enzyme systems of the newer artificial salivas. Biotène ® Dry Mouth Toothpaste contains salivary enzymes and is SLS-free.
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