PATIENT CHARACTERISTICS: Age: 21 and under Performance status: ECOG 0-2 Life expectancy: At least 2 months Hematopoietic: Not specified Hepatic: Bilirubin no greater than 2.0 times normal SGOT or SGPT less than 5 times normal Renal: Creatinine no greater than 1.5 times normal Other: Able to take oral liquid medication No GI neuropathy No other condition that may affect absorption of drug No diabetes mellitus Not pregnant or nursing Fertile patients must use effective contraception