L-asparaginase activity in plasma and other biological fluids

Abstract

An automated method has been developed for the assay of L-asparaginase activity in plasma and other biological fluids. By means of this method, L-asparaginase activity has been determined in plasma, cerebrospinal fluid, and urine in patients receiving E. coli L-asparaginase (EC-2) therapy. The height of the plasma activity was related to the dosage. In some patients, the plasma enzyme activity fell despite continued administration of L-asparaginase. The disappearance of the E. coli L-asparaginase from the plasma was related to the commercial source of the enzyme. From one source the half-life in adults was 11.2 ± 2.7 hours and from another, 22.6 ± 4.7 hours. Intramuscular administration of enzyme resulted in plasma levels that were about half those observed following intravenous administration of enzyme. Following intravenous administration of L-asparaginase at doses up to 5000 IU/kg/day, no activity was found in urine. At the highest dosage levels, small amounts of activity were observed in cerebrospinal fluid. When enzyme was injected directly into the cerebrospinal fluid, there was a rapid transfer of enzyme to the plasma, and the activity in the spinal fluid was reduced to negligible amounts within 24 hours.