When patients have their kidney or another organ transplanted due to end-stage organ failure, the body's immune system automatically tries to reject the new organ, which is the body's attempt at self-protection from foreign tissue. Immunosuppressive drugs are used to decrease the body's immune response to block the effects of this natural defense and thus prevent the body from rejecting the transplanted organ, which could be fatal for the recipient.
The main problem with immunosuppressants is that they are not very specific and suppress all of the immune system, leaving the patient vulnerable to a variety of opportunistic infections that would normally be prevented by the immune system. Patients taking immunosuppressant medications are often called immunocompromised (ie, their immune system is compromised) and are at risk for numerous complications.
Over the past 20 years, a number of new immunosuppression medications have been approved, increasing the number of options available and facilitating a noticeable evolution in therapeutic protocols. For all immunosuppressive drugs, though, the transplant patient needs to maintain a lifetime minimum level of medication in the blood to prevent organ rejection; too high a level increases the risk of serious side effects, such as kidney damage, tremors, or hypertension. Therefore, medication levels need to be managed carefully and tailored to each patient. Transplant patients typically are obliged to make frequent visits to their doctor for monitoring and dose adjustments for months after receiving the new organ.