Comparison of oral iron chelator L1 and desferrioxamine in iron-loaded patients

The efficacy of the oral iron chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L1) was compared with that of subcutaneous desferrioxamine in 26 patients with transfusional iron overload. Immediately after red-cell transfusion, 20 patients were randomised to receive either desferrioxamine (50 mg/kg daily as a 12 h subcutaneous infusion), or L1 (50 mg/kg daily by mouth). Patients were evaluated during treatment with the other drug after transfusion the next month. Mean (SD) daily urinary iron excretion was lower during L1 than during desferrioxamine (12.3 [6.7] vs 18.2 [15.3] mg/day). In 5 patients the dose of L1 was raised from 50 to 75 mg/kg daily; mean urinary iron excretion rose from 13.8 (7.0) mg/day to 26.7 (17.8) mg/day, comparable with that during desferrioxamine (24.9 [24.3] mg/day). Faecal iron excretion rose slightly over baseline in 6 patients studied during L1 administration (from 8.5 [0.9] mg/day to 12.2 [0.9] mg/day). Pharmacokinetic studies showed an elimination half-life for L1 of 117-237 min. Studies in dogs and in volunteers showed no absorption of the L1-iron complex, excluding a contribution of absorption of intraluminal complexes of L1 and food iron to urinary iron excretion. Further animal toxicity testing is needed before L1 can be studied in a broader group of patients.