Post radiation severe xerostomia relieved by pilocarpine: A prospective French cooperative study

Post-radiation severe xerostomia relieved by pilocarpine: a prospective French cooperative study

BACKGROUND AND PURPOSE

The aim of the study was: (1) to confirm the action of pilocarpine hydrochloride (Salagen) against xerostomia: (2) to correlate the response to dose/volume radiotherapy parameters.

MATERIALS AND METHODS

From June 1995 to February 1996, 156 patients with severe radiation induced xerostomia received pilocarpine hydrochloride orally. IS mg per day with a 5 mg optional increase at S weeks up to a daily dose of 25 mg beyond 9 weeks.

RESULTS

One hundred and forty five patients are fully evaluable. Treatment compliance was 75%. Thirty eight patients (26%) stopped treatment before week 12 for acute intolerance (sweating, nausea, vomiting) or no response. No severe complication occurred. Ninety ses en patients (67%) reported a significant relief of symptoms of xerostomia at 12 weeks. Within 12 weeks, the size of the subgroup ith normal food intake almost doubled (13-24 patients) while the size of the subgroup with (nearly) impossible solid food ingestion decreased by 38% (47 vs. 29 patients). The impact on quality of life was considered important or very important by 77% of the responders.

CONCLUSIONS

No difference was found according to dose/volume radiotherapy parameters suggesting that oral pilocarpine hydrochloride: (1) acts primarily by stimulating minor salivary glands: (2) can be of benefit to patients suffering of severe xerostomia regardless of radiotherapy dose/volume parameters: (3) all responders are identified at 12 weeks.

Preservation of the rat parotid gland function after radiation by prophylactic pilocarpine treatment: radiation dose dependency and compensatory mechanisms

PURPOSE

To study the ability of a prophylactic pilocarpine administration to preserve the rat parotid gland function after unilateral irradiation with graded doses of X-rays.

METHODS

The right parotid gland of male albino Wistar rats was irradiated with single doses of X-rays (10-30 Gy, at 1.5 Gy min(-1)). Pilocarpine (4 mg/kg) was administered intraperitoneally, 1 hour prior to irradiation. Saliva samples of both left and right parotid gland were collected by means of miniaturized Lashley cups 4 days before and 3, 7, 10, and 30 days after irradiation. The parotid salivary flow rate (microl/min) was used as a parameter for the assessment of parotid gland function.

RESULTS

Our data confirm that a single prophylactic treatment of pilocarpine can attenuate radiation-induced loss of gland function. Surprisingly, the effect of pilocarpine was not restricted to the irradiated gland only. Pilocarpine also enhanced the flow rate in the contralateral, nonirradiated gland. The latter effect was found for all doses above 10 Gy and became apparent around 7 days after the radiation treatment. The effectiveness of pilocarpine to attenuate function loss in the irradiated gland decreased with increasing dose and was lost after single doses of 30 Gy.

CONCLUSIONS

Our data provide direct evidence that increasing the compensatory potential of the nondamaged gland, at least in part, underlies the "radioprotective effect" of pilocarpine in case of unilateral radiation. The ability of pilocarpine to ameliorate the early radiation-induced impairment of the parotid gland function in the irradiated gland may therefore be dependent on the remaining number of functional cells, and thus on the volume of the gland that lies within the radiation portal.