DISEASE CHARACTERISTICS:

• Received more than 4,000 cGy of prior external beam radiotherapy for cancer in the head and neck region

  • Radiotherapy completed more than 4 months prior to study
• Clinically significant salivary gland dysfunction with grade 2 or 3 xerostomia
• At least 1 anatomically intact parotid gland
• No suspected or confirmed bilateral physical closure of salivary gland ducts
• No history of primary or secondary Sjogren's syndrome or other underlying systemic illness known to cause xerostomia independent of prior radiotherapy exposure

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• Karnofsky 70-100%
• ECOG 0-2

Life expectancy:

• At least 6 months

Hematopoietic:

• Hemoglobin at least 9.0 g/dL
• No anemia

Hepatic:

• Bilirubin no greater than 2 times upper limit of normal (ULN)
• SGOT/SGPT no greater than 2 times ULN
• Lactate dehydrogenase no greater than 2 times ULN
• No evidence of active liver disease

Renal:

• Creatinine no greater than 2.5 mg/dL
• BUN no greater than 50 mg/dL
• No history of nephrolithiasis within the past 6 months

Cardiovascular:

• No history of significant cardiovascular disease
• No active congestive heart failure
• No uncontrolled angina
• No significant arrhythmia
• No myocardial infarction within the past 6 months

Pulmonary:

• No history of significant pulmonary disease
• No controlled or uncontrolled asthma
• No chronic bronchitis or chronic obstructive pulmonary disease that would limit avocational activities

Gastrointestinal:

• No history of significant gastrointestinal disorder
• No active pancreatic disease
• No gastroduodenal ulcers within the past 6 months
• No hypersensitive bowel conditions requiring pharmacologic therapy
• No inflammatory bowel disease
• No history of cholelithiasis within the past 6 months (unless cholecystectomy performed)

Other:

• No clinically significant laboratory abnormality
• No history of alcohol or drug abuse within the past 6 months that would preclude study
• No prior or concurrent acute iritis or narrow-angle (angle closure) glaucoma
• Not pregnant
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• No concurrent chemotherapy

Endocrine therapy:

• Not specified

Radiotherapy:

• See Disease Characteristics
• No concurrent radiotherapy

Surgery:

• Not specified

Other:

• At least 30 days since other investigational new drug
• At least 4 weeks since prior systemic or ophthalmic pilocarpine
• No prior cevimeline
• No concurrent hyperbaric oxygen therapy
• No concurrent beta adrenergic antagonists, anticholinergic agents, cevimeline metabolism inhibitors, or other medications known to effect salivary function
• No other concurrent investigational drugs