APTT, lepirudin dosages, hirudin plasma levels, and ahir-ab concentrations.

Courses of aPTT (sec), lepirudin dosages (mg/kg bw × h), hirudin plasma levels (ng/mL), and ahir-ab concentrations (μg/mL) are given for (A) a patient with ahir-abs but no effect on aPTT levels; (B) a patient with a decrease in aPTT concomitant with the increase in ahir-ab concentration; and (C) a patient with a decrease in lepirudin dosage after formation of ahir-abs to maintain the aPTT within the therapeutic range.