New concepts of iron and aluminium chelation therapy with oral L1 (deferiprone) and other chelators. A review.

The introduction of oral chelation therapy with the alpha-ketohydroxypyridine chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L1, INN/BAN: deferiprone) in iron- and aluminium-overloaded patients has been initiated in over 15 countries in the last 7 years. Over 600 patients with various conditions, in 26 centres have received L1, in some cases daily for over 5 years. In the vast majority of iron-loaded patients, doses of 55-100 mg kg-1 of L1 resulted in urinary iron excretion levels greater than those accumulating from transfusions (15-35 mg d-1) and also reduction in serum ferritin and liver iron to near normal levels. Urinary iron excretion was related to the iron load of the patients, as well as the dose and frequency of administration of L1. The L1 appears to mobilize iron mainly from a serum iron pool in excess of transferrin saturation, transferrin-bound iron and tissue iron, mainly but not exclusively from the liver. The order of metal binding by L1 at pH 7.4 is Fe > Cu > A1 > Zn. Aluminium removal from aluminium-loaded renal dialysis patients by L1 was also effective at doses similar to those used for iron-loaded patients. Overall toxic side effects include six cases of reversible agranulocytosis, 0-30% incidence of transient musculoskeletal and joint pains, 0-6% of gastric intolerance and 0-2% zinc deficiency. Deferiprone appears to be as effective as desferrioxamine in iron and aluminium removal and has low toxicity. Its oral efficacy and low cost make it more accessible than desferrioxamine for the vast majority of patients needing iron chelation worldwide. The development of other alpha-ketohydroxypyridines is currently in progress.