Over 90% of patients experience xerostomia during head and neck radiotherapy and for three quarters of patients this can last from one month to 2 years. Xerostomia causes a variety of oral problems including discomfort chewing problems, difficulty swallowing, speech problems , dental caries, candidiasis etc. This has a significant impact on quality of life.

This review updates a 2007 Cochrane review that aimed to determine the efficacy and tolerability of parasympathomimetic drugs in the treatment of radiation-induced salivary gland dysfunction (specifically radiation-induced xerostomia).

Methods

Searches were conducted in the Cochrane Oral Health Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, CINHAL, the metaRegister of Controlled Trials, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP). Randomised controlled trials (RCTs) of any design, parallel group or cross over involving patients with radiation-induced salivary gland dysfunction being treated with parasympathomimetic drugs versus no treatment, versus placebo, versus another treatment for salivary gland dysfunction, or versus a combination were considered. Standard Cochrane methodological approaches were taken for data selection, risk of bias assessment and data analysis.

Results

• Only 3 studies involving a total of 298 patients were included.
• All three studies were included in the original review and involved pilocarpine hydrochloride.
• The data suggest that pilocarpine hydrochloride is more effective than placebo and at least as effective as artificial saliva.
• 42% to 51% of patients responded to pilocarpine, although in some the response did not occur for up to 12 weeks.
• Side effects were common with pilocarpine (for example sweating, headache, passing urine frequently, flushing), but were usually reported to be mild.
• 6% -15% of patients stopped taking pilocarpine due to side effects.

Conclusions

The authors concluded:

There is limited evidence to support the use of pilocarpine hydrochloride in the treatment of radiation-induced xerostomia. Currently, there is little evidence to support the use of other parasympathomimetic drugs in the treatment of radiation-induced xerostomia. Available studies suggest that approximately half of patients will respond, but side effects can be problematic. The conclusions of the update are the same as the conclusions of the original review, since no new relevant studies have been published in the interim.

Comments

This well conducted review provided limited evidence to support the use of pilocarpine hydrochloride of radiation-induced xerostomia so the author suggest that it is clinically appropriate to offer it to patients with no contra- indications. However, many fail to respond and side effects are common.

Another Cochrane review by Furness et al (see Dental Elf 3^rd Sept 2013) looked at non-pharmacological approaches for dry mouth although not specifically related to those patients with radiation-induced xerostomia. They included 9 studies involving acupuncture, electrostimulation devices and powered toothbrushes but the quality of evidence was low or very low.

Links

Davies AN, Thompson J. Parasympathomimetic drugs for the treatment of salivary gland dysfunction due to radiotherapy. Cochrane Database of Systematic Reviews 2015, Issue 10. Art. No.: CD003782. DOI: 10.1002/14651858.CD003782.pub3.

Dental Elf – 3^rd Sept 2013 – Insufficient evidence for effects of non-pharmacological interventions for the relief of dry mouth