Kim Annink

199 Pharmacokinetics of allopurinol in the ALBINO trial patient; but as fewer than anticipated study sites contributed to the pharmacokinetic blood sampling, sampling was delayed. In October 2019, 18 months after the first included patient, the ALBINO consortium decided to analyze all available blood samples at that time in a preliminary assessment of target exposure to inform ongoing conduct of the study as a safety measure. Blood sampling for pharmacokinetics Blood sampling was combined with clinically indicated blood samples. To limit the number of blood samples per patient there were two sampling schedules: A and B for both patients treated with hypothermia and patients who recovered quickly and were not cooled (Table 1). Investigators had to document the exact date and time of actual blood sampling for each scheduled time interval. Table 1: Sample intervals Group Sampling schedule No hypothermia A 15-60 min, 1.5-4h, 8-12h, 18-24h, 60-72h B 15-60 min, 1.5-4h, 8-12h, 36-48h, 96-168h Hypothermia A 15-60 min, 1.5-4h, trough level t=12h, 13-14h, 18-24h, 60-72h B 15-60 min, 1.5-4h, trough level t=12h, 13-14h, 36-48h, 96-168h For the pharmacokinetic (PK) analyses 0.5 ml blood was collected in MiniCollect® lithium-heparin tubes (Greiner Bio One, Alphen aan den Rijn, the Netherlands). The collected sample was placed in melting ice immediately after collection and centrifuged with a speed of 1500-2000*g for 10 minutes at 4-8°C within 30 minutes after collection. Afterwards the plasma was separated with a pipette and stored in a polypropylene crew cap in a -80°C fridge. Bioanalysis Bioanalysis was performed by Ardena Biochemical Laboratory (ABL, Ghent, Belgium). Allopurinol, oxypurinol, xanthine, hypoxanthine and uric acid in human plasma samples were extracted following protein precipitation using ethanol. After precipitation and centrifugation, the supernatant was injected into the LC-MS/MS chromatographic system for the determination of allopurinol, oxypurinol, xanthine 9