The Pharmacokinetics and Pharmacodynamics of Immunosuppressive Agents

The state of pediatric heart transplantation

Heart transplantation is now an accepted method for treatment of heart disease in children, but transplantation in pediatric recipients continues to present unique challenges. The differences in indications and the complexity of surgery for congenital heart disease are only two of those challenges. A successful means of mechanical support is not available, which puts children at special risk of dying while waiting for transplantation. In addition, physiologic differences produce issues about management after transplantation, including use of immunosuppressive agents, control of infection, identification of transplant coronary artery disease, and posttransplant lymphoproliferative disease. Because of the longer life expectancy desired from pediatric transplantation, measurement of quality of life must be more comprehensive. This broad range of special demands means that although the state of pediatric heart transplantation is positive, there are areas for continued improvement.

Drug substitution in transplantation: a National Kidney Foundation White Paper

Specific safeguards to guide the approval process and substitution practices for generic immunosuppressive agents are necessary for the effective delivery of patient care. Currently, the Food and Drug Administration (FDA) requires the demonstration of bioequivalence of generic drugs to innovator drugs in normal healthy subjects, a criterion that may be insufficient for critical-dose drugs. For generic equivalents of critical-dose drugs and for innovator critical-dose drugs, there should be a requirement for replicate studies measuring intrasubject variability and subject-treatment interactions to establish that bioequivalence holds true. Extensive testing of generic drugs in all target patient types is impractical and should not be required. However, when evidence suggests that the bioavailability of a critical-dose drug may vary substantially in certain subgroups, the FDA should require a demonstration of bioequivalence of generic versions to innovator products in these representative target populations. Changes in the approval process for generics should be accompanied by more consistent substitution practices. Pharmacists should notify the prescribing physician and patient whenever a critical-dose drug (generic or brand name) is dispensed in a different formulation from the one the patient has been taking. Therapeutic substitution for such drugs should not be made unless the prescribing physician has granted approval. The health care provider should consider instituting appropriate monitoring whenever patients are switched between generic formulations or between innovator drugs and generic formulations. Patients should be well informed about generic substitutes so that they can participate in treatment choices.