PATIENT CHARACTERISTICS: Age: 18 and over Performance status: CTC 0-2 Life expectancy: Not specified Hematopoietic: Not specified Hepatic: Bilirubin: Groups 1-4: Less than 1.5 times upper limit of normal (ULN) Group 5: 1.5-4 times ULN Renal: Creatinine clearance: Groups 1 and 5: Greater than 50 mL/min Group 2: 30-50 mL/min Group 3: Less than 30 mL/min Group 4: Less than 30 mL/min, requiring dialysis Neurologic: No history of grade 2 peripheral neuropathy No history of seizure disorder No history of neurologic dysfunction Other: Not pregnant or nursing Fertile patients must use effective contraception HIV negative