Oral pilocarpine: new preparation. Xerostomia after radiation therapy: moderately effective but costly.

(1) Dry mouth (xerostomia) is a frequent complication of radiation therapy for cancers of the ear nose and throat. Local measures such as saliva substitutes and anetholtrithione are either moderately effective, inadequately evaluated or little better than placebo. (2) Marketing authorization has been granted in France for an oral formulation of pilocarpine, an old parasympathomimetic agent, in the treatment of radiotherapy-induced xerostomia. (3) According to the results of two double-blind trials, pilocarpine (15-30 mg/day) improves symptoms in about 50 % of patients, compared to improvement in 25% of patients taking placebo. The drug is slow to take effect and has little impact on daily life. It is not known whether pilocarpine helps prevent the complications of xerostomia. (4) Most adverse effects of pilocarpine are due to its parasympathomimetic effects, such as sweating, urinary frequency, flushing, rhinitis and nausea. Pilocarpine must therefore be used with caution in patients with asthma, cardiac arrhythmia, iridocyclitis, and closed-angle glaucoma. (5) In France, this pilocarpine formulation costs 18 times more than a preparation of pilocarpine 2% eye drops used orally (off licence). (6) In practice, patients needing symptomatic treatment of xerostomia after radiotherapy may benefit from oral pilocarpine but, given its limited efficacy and its adverse effects, other local treatments should be tried first.