We report on a 42-year-old patient whose relapse of acute promyelocytic leukaemia (APL) included meningeal infiltration. Since he had previously experienced ATRA syndrome, he received arsenic trioxide (ATO) plus intrathecal therapy with cytarabine, prednisone, and methotrexate. We measured the concentration of arsenic in his cerebrospinal fluid (CSF). Arsenic showed a peak CSF concentration of 0.008 mg/l (0.11 micromol/l) and a nadir of 0.002 mg/l (0.027 micromol/l), both representing about 14% of blood levels. ATO thus crosses the blood-CSF-barrier when administered intravenously, but the concentration in CSF is probably not sufficient for treatment of meningeal leukemia.
Hair samples were collected from 17 children (7-16 years of age) who had received methylphenidate therapy on a long-term basis. The dose was 10-60 mg per day. To 20 mg of pulverized hair, phosphate buffer and internal standard (norpethidine) were added. Extraction was performed by ultrasonic treatment, followed by isolation by alkaline extraction with isohexane. Derivatization with N-Methyl-bisheptafluorobutyric amide enabled gas chromatography-mass spectrometry analysis of the perfluorobutyryl derivatives in selected ion monitoring mode. The methylphenidate concentrations lay between 0.073 and 1.1 ng/mg hair. It was noted that at higher daily doses there was a tendency toward increased concentrations in the hair, but for testing of compliance, the incorporation into hair did not occur with the required high correlation between daily dose and concentration in the hair.
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