RESUMO
PURPOSE: Effects of hemodialysis on pharmacokinetic properties and QTc were studied in 4 patients taking daily methadone dose of 100 mg (range, 60-120 mg). METHODS: Methadone in serum, dialysate, and urine were measured by LC-MS/MS. QTc was calculated with Bazett's formula. FINDINGS: The serum Cmin methadone level was 1124 nmol/L (range, 547-1581 nmol/L). Methadone dialysate clearance was 17.1 mL/min (range, 13.7-20.6 mL/min). Total loss in dialysate was 2.30% (range, 1,25-3,70%) of daily methadone intake. QTc increased from 391 msec (range, 369-406 msec) to 445 msec (range, 407-479 msec), independently of serum methadone level, which may be explained by normalization of serum electrolytes. IMPLICATIONS: Methadone dose adjustment is not needed because of hemodialysis.