A pharmacokinetic/pharmacodynamic model for the action of anti-D immunoglobulin in effecting circulatory clearance of Rh D+ red cells.

A dynamic model of the action of anti-D immunoglobulin in effecting clearance of Rh D-positive red cells from the circulation of D-negative subjects is presented. The pharmacokinetics of the redistribution of anti-D between injection site, intravascular and extravascular spaces following either intramuscular or intravenous administration is included, also the reaction of anti-D with D-positive red cells in the intravascular space and subsequent circulatory clearance of antibody-coated cells. Numerical computer modelling methods have been used to obtain solutions of the model, using kinetic rate constants which have been derived from previously published experimental data. Selected solutions are presented, chosen for their relevance to (i) clinical situations in which anti-D is used to prevent Rh D immunization of D-negative subjects and (ii) determination of some of the properties of anti-D antibodies which are important for effecting circulatory clearance of D-positive red cells.