during each 4- to 5-hr apheresis , serum phenytoin levels fell an average of 3.2 micrograms/ml and the phenytoin clearance by plasmapheresis was 21.9 +/- 2.1 ml/min ( equal to the patient 's endogenous clearance of 20.8 ml/min ) .
C0005791
apheresis
C0032134
plasmapheresis