A randomized, double-blind, placebo-controlled trial of concomitant pilocarpine with head and neck irradiation for prevention of radiation-induced xerostomia

Abstract

Background: Xerostomia is one of the disturbing side-effects of radiotherapy to the head and neck region. Pilocarpine has been approved for the treatment of this condition in the chronic phase, but its use concurrent with radiation could also be beneficial for prevention or reduction of the subsequent radiation-induced xerostomia. We undertook to test this hypothesis in a clinical trial.

Methods: At the start of radiotherapy, randomization was performed to either pilocarpine 5 mg three times daily or placebo in a double-blind setting. The drug was started with irradiation and continued until 3 months after the end of radiotherapy. Xerostomia was evaluated 6 months after the end of radiation by a subjective visual analog scale questionnaire. Also the objective grade of xerostomia was recorded by two separate observers.

Results: A total number of 60 patients were randomized into the trial, but unfortunately only 39 patients were finally evaluated for xerostomia, 18 in the pilocarpine and 21 in the placebo group. Mean age was 42 years, and mean parotid dose was 58 Gy. Mean subjective xerostomia was 40.3 mm in the pilocarpine group and 57 mm in the placebo group (P = 0.02). Also mean objective xerostomia grade was 2.2 in the pilocarpine group and 2.6 in the placebo group (P = 0.01). Subjective and objective xerostomia results were positively correlated (P = 0.01). Age and the parotid dose did not have a significant effect on xerostomia.

Conclusions: Compared to placebo, pilocarpine used with radiotherapy could lead to a significant diminishment of subsequent radiation-induced xerostomia.