Sugar-free lozenges, acidic candies, or chewing gum may produce transitory relief from xerostomia by stimulating residual capacity of salivary gland tissue (acidic products can result in demineralization of the teeth and may not be recommended in dentate patients).
Pilocarpine is the only drug approved by the U.S. Food and Drug Administration for use as a sialogogue (5-mg tablets of pilocarpine hydrochloride) for radiation xerostomia. Treatment is initiated at 5 mg by mouth 3 times a day; the dose is then titrated to achieve optimal clinical response and minimize adverse effects. Some patients may experience increased benefit at higher daily doses; however, incidence of adverse effects increases proportionally with dose. The patient's evening dose may be increased to 10 mg within 1 week after starting pilocarpine. Subsequently, morning and afternoon doses may also be increased to a maximum 10 mg per dose (30 mg/d). Patient tolerance is confirmed by allowing 7 days between increments.
The most common adverse effect at clinically useful doses of pilocarpine is hyperhidrosis (excessive sweating); its incidence and severity are proportional to dosage. Also reported, typically at doses higher than 5 mg 3 times a day, are the following:
Pilocarpine usually increases salivary flow within 30 minutes after ingestion. Maximal response may occur only after continual use (>8 weeks).[Level of evidence: I]
It has been suggested that pilocarpine given during radiation therapy may reduce salivary gland impairment and xerostomia both during and after treatment. However, in a randomized study of 249 patients with HNC, the concomitant use of pilocarpine during radiation did not have a positive impact on quality of life or patient assessment of salivary function, despite the maintenance of salivary flow.[Level of evidence: I] It has been indicated that the efficacy of pilocarpine depends on the radiation dose distributed to the parotid glands during treatment, i.e., in patients in whom the mean parotid dose exceeds 40 Gy, pilocarpine may spare parotid gland function and reduce xerostomia-particularly significant after 12 months.[Level of evidence: I]
Cevimeline (30 mg 3 times a day) also appears anecdotally to have efficacy in managing radiation-induced xerostomia.;[Level of evidence: I] Although cevimeline is approved for use only in the management of Sjögren syndrome, appropriate clinical trials are under way, and its efficacy should be established soon. While cevimeline has greater selective affinity for M3 muscarinic receptors than pilocarpine, whether this can prove advantageous for treating radiation xerostomia remains unclear.
Acupuncture appears to offer an intervention for the treatment of radiation-induced xerostomia in patients with a residual functional capacity of the salivary glands and is a treatment modality without serious adverse effects.[21,22,23] Further randomized controlled clinical trials, including sham acupuncture, are warranted.