Pharmacokinetic characterization of extracorporeal therapy

The efficiency of extracorporeal therapy with immobilized enzymes (reactive devices) and hemoperfusion cartridges (nonreactive devices) is evaluated in terms of a new pharmacokinetic parameter, the bioefficacy. A detailed analysis is provided in the former case, and it is shown how the bioefficacy can be calculated from a combined pharmacokinetic and reactor analysis. The theory is presented for evaluating bioefficacy in terms of linear pharmacokinetic models that view the reactor or other extracorporeal appliance as an artificial organ. Examples are drawn from recent work on methotrexate rescue with immobilized carboxypeptidase G₁ and from literature data on the use of hemoperfusion to treat drug overdose to illustrate the calculations.