Advice and information on preventing and curing xerostomia may be offered at the pharmacy to people with this disorder, which is often caused by several types of drugs. 

Xerostomia (from the Greek xero dry, and stoma mouth) is the subjective feeling of having a parched mouth, produced in many cases by decreased salivary secretion or changes in the biochemical composition of saliva. Patients with xerostomia often report difficulties in chewing, swallowing or even talking, especially those who wear dental prostheses. 

Xerostomia is a subjective concept, while hyposalivation refers to a decrease in the rate of salivary flow to under 0.1-0.2 mL/min of total unstimulated saliva and/or 0.7mL/min of total stimulated saliva, and is therefore objective and quantifiable. 

The prevalence of xerostomia in young adults between 18 and 35 years of age is 20%, which increases to 40% at age 55 and over, and affects more women than men.

It is therefore an increasingly common clinical entity due to an increase in life expectancy and to more frequent prescription of xerostomia producing medicines. 

XEROSTOMIA-PRODUCING PHARMACEUTICALS 

There are over 500 medicines that can alter the amount or quality of saliva, leading not only to a dry mouth, but also to the deterioration of the protective and immune functions of saliva, increasing the risk of tooth decay, fungal infections and periodontal disease, as well as affecting functions such as chewing, speaking or swallowing (mastication, phonation, deglutition, etc.) 

Over 500 different drugs marketed in Spain include xerostomia among their side effects. They are fundamentally medicines with a direct effect on the autonomic nervous system which regulates gland secretion (anticholinergics, adrenergic antagonists, etc.), or with an indirect effect on the central nervous system (antipsychotics, anxiolytics) as well as those that reduce body fluids, typically diuretic antihypertensives. 

Drug-induced xerostomia can be reversed, meaning that the problem is solved by discontinuing use of the medication. However, most of these medicines are prescribed for chronic conditions, especially in older adults, where there is irreversible degeneration of the salivary gland parenchyma (it is estimated that three out of four older adults take one of these drugs on a long-term basis). 

THERAPEUTIC STRATEGIES 

There are several therapeutic alternatives to help improve the effects of xerostomia. However, not all of them are applicable in all cases, and it is therefore necessary to diagnose the presence of xerostomia in order to develop a personalised therapeutic strategy to avoid potentially ineffective or unnecessary treatments. 

In patients with drug-induced xerostomia, the suppression, substitution or reduction of doses of medicines causing xerostomia should be considered, but that is not always possible. Additionally, the fundamental pillar of the treatment of drug-induced xerostomia focuses on prevention. 

The objective should be good oral hygiene to maintain the oral cavity in the best possible condition in order to prevent superinfection. Patients should therefore be advised to include cleaning the surface of the tongue (Halita^® tongue cleaner), and to use toothbrushes with soft filaments (VITIS^® brushes) and a non-irritant toothpaste (Xeros dentaid^® toothpaste), as well as mouthwashes containing antimicrobial products such as cetylpyridinium chloride (CPC) (VITIS^® gingival) or moisturising properties (Xeros dentaid^® mouthwash). 

Another therapeutic tool includes sialogogues (either systemic or topical, although the systemic ones have unpleasant side effects) which in one way or another stimulate the major and minor salivary glands, causing them to produce saliva. One safe topical sialogogue that has proven efficacy is 1% malic acid spray with xylitol and fluoride (Xeros dentaid^® spray), which acts as a substance capable of generating a taste stimulus due to its “sour flavour”, thereby reducing the dry mouth sensation and increasing both stimulated and unstimulated salivary flow in patients taking xerostomising medication (such as antihypertensives or antidepressants).