Pharmacodynamics of very intensified Erwinia asparaginase courses. Serum asparagine (A), aspartic acid (B), glutamine (C), and glutamic acid (D) levels (mean ± SEM) during Erwinia asparaginase therapy (20 000 IU/m²) in children without allergy to Erwinia asparaginase and without silent inactivation. Dashed lines show normal values of asparagine (40-80 μM), aspartic acid (4-22 μM), glutamine (457-738 μM), and glutamic acid (18-65 μM). The LLQ of asparagine is 0.2 μM.