Xerostomia Is More Than an Inconvenience

Xerostomia, or dry mouth, has many causes. It is associated with >500 drugs, including many OTC products. Drug-induced xerostomia accounts for 75% of reported cases.^{1 Although 10% of the population suffers from dry mouth,}2 practitioners often brush aside this poorly-understood condition as a minor inconvenience, failing to recognize its negative impact on both quality of life and general health.The average adult produces at least 500 mL of saliva daily. Salivary output varies temporally?0.1 mL/min during sleep, 0.3 mL/min when awake, and 4 to 5 mL/min when eating and chewing.3 Saliva has antibacterial and antifungal action, protects teeth from decay, facilitates swallowing and digestion, and lubricates the mouth when a person is speaking.Most people experience xerostomia as they wake from sleep. For many, however, it is a chronic and severe condition?often defined as reduced salivary flow of <100 mL per day.^{4 Chronic xerostomia increases the risk for several conditions (Table 1}3,5), with tooth decay and gum diseases being the most serious.

Etiology

Drug-induced Xerostomia

Drug-induced xerostomia has a close temporal relationship between symptoms and medication initiation or dose increases.3 Anticholinergic and M3 muscarinic receptor antagonists present the greatest risk (Table 2^{1,6). Newer agents?including omeprazole, protease inhibitors, didanosine, trospium chloride, tramadol, and new-generation antihistamines?also are linked to xerostomia.}3

Xerostomic OTC agents include some analgesics, nicotine-replacement agents, travel-sickness products with hyoscine, irritable-bowel products with hyoscine, indigestion/heartburn products containing famotidine or omeprazole, and antihistamine-containing products.7

Radiation-induced Xerostomia

Radiation therapy for oral cancers frequently damages salivary tissue and is the second leading cause of xerostomia. A single dose of only 20 grays (Gy) can cause permanent damage. Conventional treatment doses typically range between 60 and 70 Gy and reduce salivary flow by 95%. Damage usually is permanent, although unaffected salivary tissue compensates somewhat by increasing salivary flow.3

Chemotherapy-induced Xerostomia

Xerostomia is the fourth most common side effect of chemotherapy, but patients rank it third in terms of distress. Up to 78% of patients are affected, and severity correlates with the number of agents used. Paclitaxel, carboplatin, and infusional 5-fluorouracil are particularly troublesome.3,8

Disease Pathology?induced Xerostomia

Dry mouth, usually accompanied by dry eyes, is the hallmark symptom of Sj?gren's syndrome. Other disorders in which dry mouth is a serious component include dehydration, sarcoidosis, HIV infection, diabetes, anemia, cystic fibrosis, Alzheimer?s disease, Parkinson?s disease, rheumatoid arthritis, lupus, stroke, hypertension, and salivary duct infection.4,9 Nasopharyngeal obstructions also contribute to xerostomia, because sufferers must breathe through the mouth.

Age-induced Xerostomia

Normal aging is associated with up to 40% decreased salivary output. Because seniors present with many known risk factors?systemic disorders and the use of medications with xerostomic properties?up to 50% of seniors suffer from xerostomia, and 20% present with severe xerostomia.3,10,11Finally, tobacco use, alcohol use, and excessive salt intake, along with eating overly spicy and acidic foods, contribute to dry mouth.

Treatment

The focus of treatment is threefold: symptom relief, preventing tooth decay and gum disease, and stimulating salivary flow. Following a comprehensive assessment, reversible causes should be treated. For drug-induced xerostomia, practitioners should modify the dose and/or the drug regimen whenever possible.12

Symptom Relief Tips

Counseling should include the following tips:Sip water and sugar-free drinksChew sugarless gum or suck on sugarless hard candiesUse a humidifierBreathe through the nose, not the mouth. If nasal passages are blocked, see a doctor to correct the blockage.Practice good dental hygiene. Use fluoride toothpaste and rinses, floss twice a day, and get regular dental checkups.Treat cracked lips with petroleum jelly; use lip balmEat high-moisture foods (eg, mashed potatoes instead of French fries)Avoid tobacco, alcohol (including alcohol-containing mouthwashes), coffee, tea, sugar-containing sodas, and spicy and acidic foods

Lubrication Products

Several OTC artificial saliva products exist (eg, Orajel), most containing carboxymethylcellulose or mucin. These products merely lubricate and moisturize and do not mimic saliva's natural effect in preventing tooth decay, oral infections, and mouth sores. Relief generally is limited to 2 hours.4Fewer than 10% of sufferers use these products.1 Mucin sprays are especially effective in seniors and in those with xerostomia secondary to radiation.More recently, researchers have designed an intraoral device to be worn at night (similar to a mouth guard) with time-released lubricating gel. Research indicates high acceptance by patients, with a significant lessening of xerostomia severity.13

Pharmacotherapy

Despite the prevalence of xerostomia, few FDA-approved agents exist. Systemic pilocarpine is approved for xerostomia secondary to radiation therapy and Sj?gren's syndrome, but it has limited benefit for drug-induced xerostomia. The maximum treatment effect occurs in 6 to 8 weeks.1 This drug is well-tolerated by patients. Hyperhidrosis (increased sweating) is its most common side effect. Although less common, nausea, flu-like symptoms, headache, urinary frequency, and gastrointestinal discomfort may occur. Pilocarpine is contraindicated in patients with acute asthma, iritis, and narrow-angle glaucoma.

Cevimeline is approved for xerostomia secondary to Sj?gren's syndrome. Hyperhidrosis, nausea, and rhinitis are the most frequent side effects. This drug is contraindicated for patients with acute asthma, iritis, or narrow-angle glaucoma and lactating mothers.

Numoisyn Liquid is a saliva substitute containing linseed oil. Its manufacturer reports that 73% of patients using it improve within 7 days.^{14 Numoisyn Lozenges contain malic acid, which stimulates salivary secretion. Patients report symptom improvement with the lozenges in as little as 3 days.}14 Both agents are well-tolerated but short-acting, and multiple daily doses are required.References

1. Pharmacy update?Dry mouth: how to treat it. (Disease/Disorder overview). Chemist & Druggist (March 31, 2007): 17. InfoTrac OneFile. Thomson Gale. Fairfax County Public Library. June 1, 2007.

2 Align Pharmaceuticals. Managing your xerostomia (dry mouth). Available at: www.alignpharma.com/products-patients-numoisyn.htm. Accessed May 31, 2007.

3. Porter SR, Scully C, Hegarty AM. An update of the etiology and management of xerostomia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004;97:28-46.

4. Independent Nurse: Clinical?Xerostomia?Dealing with a dry mouth. GP (March 24, 2006): 18. InfoTrac OneFile. Thomson Gale. Fairfax County Public Library. June 1, 2007.

5 American Dental Association. Xerostomia (dry mouth). Available at: www.simplestepsdental.com/SS/ihtSS/r.WSIHW000/st.31937/t.25022/pr.3.html. Accessed May 31, 2007.

6. OTC: 10 POMs that cause dry mouth.(Prescription Only Medicine) (Brief article). Chemist & Druggist (March 17, 2007): S16. InfoTrac OneFile. Thomson Gale. Fairfax County Public Library. June 1, 2007.

7. OTC: OTC medicines that commonly cause dry mouth. (Brief article). Chemist & Druggist (March 17, 2007): S16. InfoTrac OneFile. Thomson Gale. Fairfax County Public Library. June 1, 2007.

8. Davies AN, Broadley K, Beighton D. Xerostomia in patients with advanced cancer. J Pain Symptom Manage. 2001;22:820-825.

9. Dry mouth. Available at: www.medicinenet.com/dry_mouth/article.htm. Accessed May 19, 2007.

10. Matear DW, Locker D, Stephens M, Lawrence HP. Associations between xerostomia and health status indicators in the elderly. J R Soc Health. 2006;126:79-85.

11. Matear DW, Barbaro J. Effectiveness of saliva substitute products in the treatment of dry mouth in the elderly: a pilot study. J R Soc Health. 2005;125:35-41.

12. Taubert M, Davies EM, Back I. Dry mouth. BMJ. 2007;334:534.

13. Frost PM, Shirlaw PJ, Walter JD, Challacombe SJ. Patient preferences in a preliminary study comparing an intra-oral lubricating device with the usual dry mouth lubricating methods. Br Dent J. 2002;193:403-408.

14. Align Pharmaceuticals. Product Brochure for Numoisyn. Available at: www.alignpharma.com/documents/ALIG-030-mech-v2.pdf. Accessed May 31, 2007.