The efficacy of pilocarpine and bethanechol upon saliva production in cancer patients with hyposalivation following radiation therapy

Purpose. Pilocarpine and bethanechol have been reported as potentially effective sialogogues for xerostomic patients. The purpose of the present study was to compare the efficacy of bethanechol to that of pilocarpine in patients with dry mouth following cancer therapy. Study design. Patients with documented hyposalivation were provided pilocarpine or bethanechol for 2-3 weeks in an open-label randomized crossover study. Baseline and weekly whole resting saliva (WRS) and whole stimulated saliva (WSS) were obtained for 5 minutes. Subjective response and side effects were recorded. Results. Forty-two xerostomic patients who had received radiation therapy to the head and neck participated. The increase in the WRS and WSS with each medication independently was limited. Statistically significant increase in WRS was seen for both medications when all patients using either agent were analyzed, but no statistically significant increase in WSS was found. Twenty-seven patients completed the crossover protocol. No significant difference in the effect was noted between each of the 2 drugs whether they were prescribed as the first or second drug in the crossover. Statistically significant improvement in subjective report of saliva production/mouth wetness was seen for patients on either medication. This study suggests that subjective improvement in symptoms of dry mouth may be related to resting saliva production, and not to stimulated saliva production. No statistically significant differences in adverse side effects were reported between the medications prescribed. The most common side effects were minor and included frequent urination, dizziness, and increased sweating. Conclusions. The findings indicate that head and neck radiation-treated patients with established hyposalivation will respond minimally to systemic sialagogues and while they may experience an increase in resting saliva little change in stimulated saliva may occur. It is not known whether relatively small increases in saliva are beneficial in maintaining oral health; however, subjective improvement suggests improved quality of life. While it is not known if prolonged use of a sialagogue will have increased effects, the limited increase in saliva seen following the second drug of the crossover suggests that prolonged use of a sialagogue may further increase saliva production.