Oral pilocarpine (5 mg t.i.d.) used for xerostomia causes adverse effects in Japanese

Abstract

Objective To evaluate Japanese tolerability to pilocarpine of 5 mg t.i.d. Methods From January 2006 to July 2006, 39 patients with xerostomia received 5 mg t.i.d. pilocarpine for at least for 12 weeks unless they had experienced unacceptable adverse effects. All patients received radiotherapy that included the parotid glands in the radiation field >50 Gy. The body weights of the patients ranged from 42 to 73 kg (median 60 kg). Results Thirty-six of the 39 patients were evaluable. The tolerated rate was only 47%. Of the 25 patients whose body weights were less than 65 kg, the tolerated rate was 36%, whereas the rate of the 11 patients whose body weights were 65 kg or above was 72% ( p = 0.050). The most common adverse effect was sweating with an incidence of 64%. Response rate, which was defined as the total number of patients with an increase of at least 25 mm from the baseline in the VAS score divided by the number of maintaining patients among those who started pilocarpine after more than 4 months from the start of radiotherapy, was 40% at 12 weeks ( n = 15). Conclusion For Japanese, 5 mg t.i.d. pilocarpine caused a high incidence of unacceptable adverse effects. A lower dose of pilocarpine needs to be considered.