Long-term trial with the oral iron chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L1). II. Clinical observations.

1,2-Dimethyl-3-hydroxypyrid-4-one (L1) has been given daily for 1-15 months to 13 transfusion dependent iron loaded patients. No significant change occurred in liver, renal or cardiac function, ECG and radionucleotide angiocardiogram, in audiometry tests and in visual function and electrical retinography. No skin rashes, gastrointestinal symptoms and no neurological changes that could be detected clinically were observed. Two of the patients died of their underlying diseases. One patient had severe cardiac abnormalities before receiving L1 and died of congestive heart failure with infections 5 weeks after stopping a 2-month course of L1. The other, a patient with myelodysplasia suffered recurring infections due to progression of the disease. Joint and muscle pains occurred in five patients. In two these disappeared despite continuing the drug; another patient developed swollen ankle joints which gradually resolved on stopping L1 therapy; a patient with underlying osteoarthritis complained of mild pain and stiffness in her knees which remained intermittent both on and off the drug while in the fifth patient peripheral small joint swelling and pain present before starting L1 improved with L1 therapy. One patient, with Blackfan Diamond anaemia, developed a Lw red cell antibody 6 months after commencing L1. This disappeared on stopping the drug and did not reappear. She then developed severe agranulocytosis and thrombocytopenia 6 weeks after recommencing L1 after 3 months discontinuation of the drug. No other patient showed a change in granulocyte or platelet count.