Important interactions of drugs with immunosuppressive agents used in transplant recipients.

Solid organ transplant recipients depend on multiple immunosuppressive drugs, given in combination, to prevent rejection of their allografts. These patients often require many other therapeutic agents to treat underlying illnesses or concurrent diseases. Whenever a new medication is administered to a transplant patient, the potential exists for increasing or decreasing the tissue concentrations of immunosuppressive agents. This can lead to serious complications, such as over-immunosuppression and infection, under-immunosuppression and acute rejection, or additive toxicities, including nephrotoxicity. New immunosuppressants are under development and in clinical use, such as FK506, deoxyspergualin, OG 37-325, rapamycin, brequinar, and mycophenolate mofetil, thereby creating the possibility of many new drug-drug interactions.