Toxic-therapeutic ratio of sodium cyanate

Six patients with sickle cell anemia were treated with sodium cyanate (30 mg/kg/day). In four, treatment was stopped because of definite or suspected toxicity, and no improvement was seen in the other two. Most alarming was the sudden development of peripheral motor neuropathy in a patient whose red blood cells contained less than 0.6 mols NCO-/mol of hemoglobin: six months after treatment was stopped, function had not completely returned in this patient. Safe oral dosage regimens may not be effective, but extra-corporeal treatment of sickle cells with cyanate, or other compounds, might circumvent that problem.