Xerostomia

Drug Store News,  April 26, 1999  by Carol Dickson McKee

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Introduction

Xerostomia, often referred to as dry mouth, is a common problem that not only impairs health, but also may dramatically affect quality of life. An understanding of normal saliva formation and function and common causes of, complications from and methods to treat xerostomia will provide the pharmacist with valuable insights to help improve patient function and quality of life.

Xerostomia refers to the patient's perception of oral dryness, usually due to the lack of normal secretions. It is most commonly due to decreased salivary flow; less commonly, there may be a complete cessation of salivary flow. Dry mouth may also be caused or worsened by dry air, breathing through the mouth and cigarette smoking, among other factors.

What is xerostomia?

What is [saliva?.sup.(37)(37)(40)]

Saliva is the clear, usually alkaline, somewhat viscid secretion from the parotid, submaxillary, sublingual and smaller mucous glands of the mouth. Saliva consists primarily of water, but also contains enzymes and other proteins, small organic molecules, electrolytes and constituents of nonsalivary origin (Table 1). The details of salivary secretion are outlined in Figures 1 and 2.

What does saliva [do?.sup.37-40]

Saliva aids in speech, taste and the preparation of food for digestion. Saliva also often provides a first defense against chemical, mechanical and infectious attacks. Its many protective functions include lubrication, antimicrobial activity, remineralization, cleansing, buffering and helping to maintain mucosal integrity. Functions of saliva are detailed in Table 2.

Common signs and symptoms of [xerostomia.sup.37-40]

Signs and symptoms of xerostomia include complaints of dry mouth, fissures or sores at lip corners (angular cheilosis/cheilitis), halitosis, difficulty with speech and swallowing and the constant need for fluids. Chewing some types of food, particularly dry foods, is also difficult. The tongue is frequently described as "burning" or "tingling," and changes in taste are common.

The oral mucosa loses its usual moistness and glistening properties and becomes dehydrated and fissured. It is frequently inflamed and erythremic, though it may also appear pale and thin. Tissue may be cracked and bleeding and there may be fissuring and lobulation, especially on the dorsum of the tongue.

Patients with dentures or prostheses are likely to have difficulty wearing them as long as usual. Xerostomia decreases the oral pH and significantly increases the development of plaque and dental cavities or caries; these are often located at sites not generally susceptible to decay. Xerostomia may alter the normal mouth flora, increasing especially the concentrations of Streptococcus mutans and Lactobacillus, two microorganisms which have been associated with dental decay. Candidiasis is common, especially on the tongue and palate. Gingivitis and periodontal disease may also occur.

Saliva, which is present, is thicker and more stringy than usual and there is difficulty milking saliva from the ducts of the major salivary glands.

Additional problems caused by [xerostomia.sup.38]

Nutritional problems, both with respect to quantity and quality of food selected, may occur in patients with xerostomia, especially in those who experience alterations in taste. Sleep may be disrupted both by thirst and by the necessity of making frequent nocturnal visits to the bathroom secondary to fluid ingestion prior to bedtime. Xerostomia may make speaking difficult, and patients may make smacking sounds because the tongue tends to stick to the hard palate. Patients may develop social phobias and avoid public speaking, talking on the telephone and other types of socializing. All of these factors decrease a patient's quality of life.

Of particular note to the pharmacist is the decrease in compliance possible secondary to difficulty patients may have swallowing their medications. Dry mouth may also delay the dissolution of sublingual tablets, such as nitroglycerin.

Common causes of [xerostomia.sup.37-40]

Common causes of xerostomia include medications, irradiation to the head and neck and organic and psychogenic diseases. Classes of medications that commonly cause xerostomia include anorectics, anticholinergics, antidepressants, antihistamines, antihypertensives, antiparkinson medications, antipsychotics, antispasmodics, decongestants or other sympathomimetics, diuretics, sedative/hypnotics and possibly narcotic analgesics. The potential to cause xerostomia generally increases as a medication's anticholinergic properties increase, and within each category of drugs there is often a wide range of anticholinergic activity. It is often possible, therefore, to decrease xerostomia by changing from one medication to another (Tables 3 and 4). Some cancer chemotherapeutic agents, including methotrexate and fluorouracil, may also cause xerostomia, usually by their direct action on the salivary glands.

Xerostomia is one of the most frequent side effects of irradiation to the head and neck and is due to changes in the salivary glands. It tends to worsen as the dose of irradiation increases and may or may not be reversible upon cessation of irradiation. Irradiation-induced xerostomia may also be exacerbated by the use of some cancer chemotherapeutic agents.